By Dr Joe
Does fruit spike insulin? Does fruit spike blood sugar?
Both questions are valid and deserve attention. Because fruits innocence can easily be mistaken. As usual I go deep on this topic.
We are encouraged to eat fruits as part of a healthy diet. Can something be this good and be just as bad for us?
Let me clarify something upfront. This piece is not saying you shouldn’t eat fruits. Rather it’s a deep insight into whether fuits can spike insulin or spike your blood sugar.
The US food and drug administration recommends 2 servings of fruits a day even amongst those whose level of physical activity is less than 30 minutes a day.
Although the official website does talk about how much fruit you need daily would depend on age, sex and physical activity.
In the UK, we are advised to eat 5 portions of fruits and veg daily to keep the doctors away from our doorstep.
All in all, you are encouraged to consume fruits daily. Any fruit. In any form.
I will disagree with some aspects of the recommendation especially if we are going to answer the question of whether fruits can spike blood sugar or spike insulin.
You will see what I mean as I delve deeper into the fruits and blood sugar & insulin connection.
Not that we need any encouragement to eat fruits anyway. The mere fact of their sweetness and fleshy texture is enough to make us fall in love with fruits.
Our love for fruits is evolutionary. In the prehistoric times over 2 million years ago, our diet was carbohydrate-poor, rich in protein and fat.
At the time, the only way we satisfied our sweet tooth was through fruit consumption. Fruits were more pleasant on the palate than leaves and roots. Indeed, it was important to have these substitutes when the hunter-gatherer couldn’t make a catch.
Instead of going hungry because the deer survived our hunting attempt, you had berries, veggies and roots to fall back on. Not a big deal.
Whilst it made sense at the time to eat all fruits that came our way, so long as they were considered safe, our modern way of life has now thrown some questions regarding the effects of fruits on blood sugar and insulin.
This is inextricably tied up to our modern lifestyle of being sedentary. All of these do have implications as to how our body deals with the sugar that erupts from the fruits we eat.
So, does fruit spike blood sugar and insulin?
Well, the answer is, Yes and No.
Yes, fruits can spike blood sugar.
Yes, fruits can spike insulin.
And No, fruits may neither spike blood sugar nor insulin.
Confused? Don’t be.
And I’m not giving a cop-out answer here. You know I am not one for sitting on the fence. It hurts the bum…badly.
Whether fruits spike blood insulin or spike blood sugar or not, depends on a number of factors.
And this would vary from person to person. In fact, whether your blood sugar or your insulin spikes after you eat fruit can also vary within you as an individual.
Here are some of the factors that would determine if fruits will spike your insulin or spike your blood sugar:
- Type of fruit
- How the fruit is eaten
- How much of the fruit you eat
- What you eat the fruit with
- Where you are in your metabolic health
- Your level of physical activity
Let’s take each of those factors and see how they play out.
1. Type of fruit
I don’t need to tell you that some fruits are sweeter than others. Even the same fruit can have different variations. Think Green Apples and Red Apples.
Red apples are tastier than green apples. Green apples sometimes border on the savoury side than sweet. Amongst the red apples, I’ve lost count of how many types my supermarket throws at me. Choices, choices, choices.
I’m encouraged to buy some brands of red apples because according to my supermarket, they are sweeter.
That’s just apples.
If you take things further and compare sugar between fruits, that could take a huge table of facts that might be difficult to digest (no pun intended).
So, I will keep things simple.
The amount of sugar in cantaloupe or honeydew melon is twice the amount in strawberries. Gram for gram you will be getting double the dose of sugar from honeydew melon and cantaloupe than you would, if you ate strawberries.
What about pineapples and mangoes? They are in a different league.
The flipside of that is there are some fruits that you will consider as being very safe as far as blood sugar spiking and insulin spiking are concerned.
Raspberries, blueberries, blackberries, strawberries are generally safe fruits for blood sugar and insulin spikes. So safe the berries are that diabetics are actually encouraged to eat them.
If you take things a little further in terms of fruits safety from blood sugar spikes, avocado is one fruit that should be considered a safe bet. Avocados are fatty though but the sugar level is pretty tolerable. Just something to bear in mind.
Depending on the other factors that I will be discussing shortly, a certain fruit can spike your insulin correspondingly after spiking your blood sugar on a given day.
What fruit you eat matters.
2. How the fruit is eaten
If you eat fruits whole and fresh, the soluble and insoluble fibre in the fruit keeps the release of sugars from the fruit in check.
There is a reason people like Eric Rimm from Harvard School of Public Health recommend that fruits be eaten whole.
Fruits contain not just natural sugars but also fibre and micronutrients. The fibre in fruits is both soluble and insoluble. The soluble fibre is what stops the fruit from releasing the natural sugars briskly.
The insoluble fiber does other things like serving as a prebiotic to our gut bacteria. Not only that, insoluble fiber helps move food along the alimentary tract, keeping us regular (if you get my drift).
I like making smoothies and of course I make my own smoothies. You should too.
However, I have had to rein in my love of smoothies because the process of making smoothies does break down the fibre we are talking about.
When you blitz the fruits in your smoothie machine, you are blitzing the fibre and altering the digestibility of the fruits.
In theory, you are encouraging the sugars in the fruits to be released a little quicker than they would, if you ate and chewed your fruits whole.
The finer the texture of your smoothie, the higher this effect.
Now, I should add that this effect may not be too significant in a person who is metabolically competent. I will touch on this shortly.
From the above, you would have gathered that if you are going to consume smoothies, please make your own smoothies. At least you know what’s gone into the smoothie.
Never buy smoothies from the shops or your supermarket. They invariably add sugars to those commercially available smoothies. You will be shocked at how much sugar is added.
As if the fruit isn’t sweet enough?
The point here being, whereas eating a whole fruit may not spike your blood sugar or spike your insulin, the smoothie version may spike your blood sugar and insulin.
The only way to find out is; if you test yourself using a blood glucose meter eating both versions. I encourage you to test yourself, by the way. More so, if you have insulin resistance, prediabetes or diabetes.
Lest I forget. Dried fruits and Canned fruits.
Whereas fresh fruits might be good for your blood sugar and insulin, the dried version of the fruit may turn out to be a devil in disguise.
Think grapes and raisins. Do you think eating 30 grapes will have the same effect as eating 30 raisins?
For a start, 30 grapes will fill you up more, 30 raisins will do no such thing. Agreed?
Secondly, the release of simple natural sugars from the raisins will be faster than you get from the grapes even though both the grapes and the raisins have the same amount of sugar.
It is the speed of sugar release that will affect the likelihood of a blood sugar spike and a corresponding insulin spike.
Dried fruits will certainly move you in that direction.
Dried fruits are fruits that have lost nearly all the water content. Not only that some food manufacturers are crazy enough to add sugar to some dried fruits to sweeten them up some more.
How much sweetness do we need in our lives?
Think dried berries, cherries and apricots.
The same goes for canned fruits. Some have added sugar in them. Avoid.
If you ever going to have canned fruits, ensure they are preserved in water. If there’s any added sugar, avoid.
Because those brands of canned fruits with added sugar will most certainly spike your blood sugar and spike your insulin.
3. How much of the fruit you eat
This is common sense really.
If you are going to gorge on something sweet, it makes sense to be sensible about it.
If you are going to eat 10 apples in one sitting because you are chatting with your friend and you’ve lost track of how much apples you have eaten (10 actually, need I remind you), is it any surprise if the apples spike your blood sugar and your insulin?
Then again, it also depends on other factors playing up to either protect you or conspire against you. I’m referring to the type of fruit, how you eat it, your metabolic status etc.
All of those factors will determine whether 10 apples or 10 oranges may spike you or not.
I’m not one to talk, because I actually eat lots of bananas. The most bananas I have eaten is 5 in one sitting. But I was fine. I’m no longer insulin resistant and the bananas by the way are the minimally-ripe ones not the deep yellow over ripe ones with brown patches on the skin.
I eat lots of minimally-ripe bananas to catch up on my resistant starch.
I’m pretty sure if I ate 5 of those over-ripe bananas, my blood sugar will rocket up.
And I don’t eat those bananas blindly, by the way. I have a glucometer and I check my blood sugar to ensure I am not being reckless.
Okay, I could get away with eating lots of bananas, will I get away with eating lots of honeydew melon?
I’m not so sure. I haven’t tested it, so I can’t say.
What I can tell you though is; honeydew melon is a fruit that is not only high in sugar (we established that already earlier on) but low in fibre.
And as you know, melons are so soft that the texture is almost non-existent.
What does that mean?
It means you can easily eat lots and lots of a fruit like watermelon without realising you have. In addition, the fact that watermelon or honeydew melon has very little fiber means fruits like honeydew melon or watermelon will give you a blood sugar spike and an insulin spike.
The way round it is, if you are going to eat fruits like melon with high sugar and low fiber, you will need to reduce your portion sizes to less than a cup.
High fiber fruits like the berries are a safer bet when it comes to eating bigger portions of fruits, if you want to avoid insulin spike and blood sugar spike.
Something else I need to mention about canned fruits is that you can very easily eats lots of canned fruits than you would eating the whole fruit version of it.
You need to be mindful of that.
4. What you eat the fruits with
Before I started writing this article, I had some fruit. Apples and Blueberries.
But I didn’t just eat the apples and blueberries on their own, I had the them with oatmeal.
I like doing that. Why?
Because oatmeal as you know has lots and lots of fibre. Fiber is good for you.
Oat meal has fibre. The apple has fiber. The blueberries have fiber. What have I succeeded in doing with that combination?
Not only have I succeeded in boosting my fiber intake for the day, I have also ensured that the release of blood sugar from that meal is as slow as it will ever get.
You can apply the same principle of introducing more fiber to your fruit intake by having your fruits with leafy green vegetables, if oatmeal is not your thing.
Leafy greens have lots of fibre to boot. You can’t go wrong with them. In fact, I will go as far as saying fruits like honeydew melon with low fiber content on their own, are best eaten as eaten as salads with leafy green vegetables.
The flipside of that is what my teenage son did the other day.
I came downstairs to the kitchen and saw him having strawberries. How cool is that? A teenager having fruit?
They usually have little interest in fruits. But wait for it…
He was having the strawberries with sugar draped over them. Yes, he was. See image below.
Strawberries are supposed to be one of the best fruits you can ever eat. But here we have a situation where my son was turning one of the healthiest fruits into something potentially unhealthy.
Will a combination like this cause the fruit to spike your blood sugar and spike your insulin? Very likely.
5. Where you are in your metabolic health
I have sort of touched on this in a roundabout way already.
We are all at different places in our metabolic health. Some of us are still metabolically competent. However, 24% of adult population in the US for instance, is thought to be insulin resistant.
Others are quite frankly diabetic.
How the fruit you eat interacts with you is strongly dependent on your metabolic status. The older you are, the higher the likelihood that you may be metabolically incompetent.
Which means fruits that wouldn’t spike you in your 20s will now spike your blood sugar in your 40s and beyond. Because you are probably insulin resistant.
Fruits like bananas, watermelon, apples, pears, nectarines, apricots, oranges, pineapples etc are fruits that won’t do someone with insulin resistance, prediabetes and diabetes any favours especially when eaten on their own.
But if you can make yourself insulin sensitive, then you may well welcome these fruits back into your life without any hassles.
How do you eat fruits without spiking your blood sugar if you are insulin resistant, have prediabetes or have type 2 diabetes?
Look out for these tips later on.
6. Your level of physical activity
Nothing beats the cellular capabilities of someone who is physically active. You hear it everywhere. Exercise, exercise, exercise.
Most advice on exercise is geared towards weight loss. That is correct but I do think that’s a misplaced advice. Exercise does little for weight loss and I mean that.
Exercise does a whole lot more for improving your metabolic health than it will ever do to make you shed fat.
If you do nothing else, do your exercises to boost your metabolic health.
The principal gain from exercise is improving insulin sensitivity.
If you built muscle as a result of your exercise activity, even better.
Muscle soaks up glucose from the blood circulation thereby lowering blood sugar. This prevents blood sugar spike and insulin spike.
Even if you don’t build muscle, just doing regular exercise will sensitize your muscles and make them more responsive to insulin.
If you boost your insulin sensitivity, fruits you eat will not cause a blood sugar spike and will therefore not cause insulin spike.
If you do nothing else, just increase your level of physical activity. You don’t have to visit the gym. See how you can boost your metabolic advantage by doing the things you do every day better.
As you can tell, the implication is; if you are very sedentary, you increase your risk of having fruits spiking your blood sugar and spiking your insulin.
Being sedentary is one of the worst things you can ever do to your metabolic and overall health.
Okay, here is how you can eat fruits without spiking your blood sugar or spiking your insulin:
- Eat high fiber fruits
- If eating low fiber fruits, keep quantity small
- Avoid dried fruits
- Eat whole fresh fruits
- Avoid fruit juice
- Avoid shop-bought smoothies
- Make your own smoothies instead. Whole fruits better than smoothies though.
- Avoid canned fruits
- Add more fiber to your fruits by eating fruits with other high fiber foods in combination
- Eating fruits with protein like nuts, nut butter or seeds can also slow down digestion
- Don’t eat fruits with added sugar
Suggested further reading:
Drink THIS first thing in the morning (3 Major Benefits)
By Dr Joe
What do you get on this page regarding blood sugar spikes and crashes?
Well, in a nutshell, you are going to get the know-how on what a blood sugar spike is, what a blood sugar crash is, why your blood sugar actually spikes and crashes, the event, what triggers a blood sugar crash, the symptoms of blood sugar crash and how to prevent a blood sugar crash.
Blood sugar spikes and crashes. Don’t you just hate it when that happens to you. It’s like your body doesn’t know what it wants to do.
Blood sugar high one minute, then low the next. Why can’t my blood sugar stay in the normal zone?
It’s easy to point the finger at our bodies but we should ideally be pointing the finger at the kinds of foods we eat, if blood sugar spikes and crashes are a frequent occurrence.
A blood sugar high followed by a blood sugar low is invariably the result of dietary choices. Yes, there are a few other causes besides diet but for the most part, diet is to blame for blood sugar spikes and crashes.
What is a blood sugar spike?
In simple terms, a blood sugar spike is one that overshoots beyond the expected target blood sugar for the index event.
Right, I can hear you shouting…WHAT?
…at your computer screen or smart phone. Dr Joe, explain some more.
Okay, let me explain.
The American College of Clinical Endocrinologists has a recommended target blood sugar level for when we are fasting, blood sugar level at 1 hour after we eat and target blood sugar 2 hours after a meal.
The recommended blood sugar target levels are shown in the image below. So, if your blood sugar overshoots above that recommended target, then that is a blood sugar spike.
You should see the target as a ceiling rather than something to aim for.
So, for instance, if 1 hour after your meal, your blood sugar is 180mg/dl (10mmol/l), that is well over the recommended 1-hour post-meal level of 140 mg/dl (7.8mmol/l). That will constitute a blood sugar spike. Does the definition of a blood sugar spike make sense to you now? I hope so.
Now, what is a blood sugar crash?
A blood sugar crash is when your blood sugar level takes a nose-dive below 72mg/dl (4.0mmol/l). People respond differently to low blood sugar levels differently.
I, for instance can still function reasonably well with blood sugar level of 63mg/dl (3.5mmol/l).
You, on the other hand may be hitting rock bottom at such a level with nasty symptoms of blood sugar crash.
The point being; everyone is different. If you are having sugar crash symptoms and your sugar is below 72mg/dl (4.0mmol/l), then it makes sense to act. It’s a crash!
What happens in blood sugar spikes and crashes?
It’s a very simple chronology of events.
You have your meal.
The food is broken down to smaller units by the process of digestion. Usually this refers to a carbohydrate meal which is broken down to glucose.
The glucose is absorbed from the intestines into the blood stream.
Once your blood sugar rises above 100mg/dl (5.5mmol/l), the beta cells in your pancreas receive an alarm call to lower blood sugar back down to normal.
The beta cells respond by releasing the stored insulin hormone inside them into the blood stream to lower blood sugar. Yes, your pancreatic beta cells store insulin inside them ready for action when needed.
Insulin is like a firefighter waiting at the fire station waiting for a call to put out fire in a building. The fire station being the pancreas. Insulin is just there waiting to be released when the call comes along.
And “the call” comes along once blood sugar rises above 100mg/dl (5.5mmol/l).
Once that happens, insulin is released into the blood stream.
The release of insulin happens in pulses. The 1st release should do the job of lowering blood sugar back to below 100mg/dl (5.5mmol/l).
If the first phase of insulin does not lower blood sugar to the desired level, then a 2nd release takes place 20 minutes later.
The 2nd phase insulin response to the high blood sugar is expected to bring blood sugar back down to normal levels.
In a person whose metabolic pathway is intact, this sequence of blood sugar rise and lowering of the blood sugar happens smoothly without any drama.
So, what then triggers the blood sugar spike and the crash?
Glad you asked.
In an individual that experiences blood sugar spikes and crashes, the action of the beta cells in the second phase insulin release is the issue.
It would appear that the pancreas gets “too excited” at the prospect of being asked to release some more insulin in the 2nd phase response.
What then happens is that; the beta cells of the pancreas respond too dramatically in phase 2 release, pushing out more insulin than is required for the remaining blood sugar lowering task.
The net result is a dramatic fall in blood sugar resulting in the blood sugar crash.
And the symptoms of blood sugar crash are not very pleasant.
Symptoms of blood sugar crash includes headaches, dizziness, trembling, sweating, nervousness, feeling agitated, becoming weak and fatigued. Follow that link for a complete look at the symptoms.
The initial blood sugar crash symptoms you feel are due to the release of adrenaline. The adrenaline is released by your body in response to the stress of the blood sugar crash.
Here’s something else that happens:
One of the symptoms of blood sugar crash is hunger. Do remember, I said earlier on that your pancreas releases a disproportionate amount of insulin to lower the blood sugar spike.
This disproportionate amount of insulin released into the circulation is what causes the blood sugar crash following the blood sugar spike.
The insulin produces a sudden “whoosh effect” clearing the sugar from the blood circulation by forcing the sugar into the cells in a dramatic way.
That’s not the end of the story though. The disproportionate high amount of insulin circulating in the blood does something else.
It makes you hungry!
Yes, Insulin makes you hungry.
Which means you want to eat again. In a way, it’s actually a protective effect. Insulin makes you hungry so you eat to replenish your low blood sugar. This is because low blood sugar is dangerous and your body doesn’t like it one bit.
Depletion is a trigger for Repletion. Kinda makes sense, right?
So, you eat again and if you keep eating the wrong foods that trigger the blood sugar spike and crashes, the process will repeat itself again.
You end up with a blood sugar spike and crash roller-coaster ride.
So, what foods are the wrong foods that trigger blood sugar spike and crash?
You guessed it. Refined carbs and Sugary foods, I’m afraid.
Refined carbs are easily digestible. This means they get digested very easily releasing their glucose units quickly.
Quick digestion, quick glucose absorption equates to quick rise in blood sugar and of course a blood sugar spike.
Then the cascade of events I described above ensues. See image below.
Carbs belong to 3 main groups:
- Refined carbs
- Wholegrain carbs
Sugar refers to table sugar, fizzy drinks and sodas, candies, milk chocolate, your favourite Starbucks coffee and even Costa. In short, any sweets fall into this category.
Refined carbs refer to carbohydrate foods that have been stripped of their bran and germ leaving the endosperm only. Exposed endosperm is a recipe for quick digestion, quick absorption and blood sugar spikes.
Refined carbs lack the fiber that slows down the digestive process. Examples of refined carbs are white rice, white flour, white bread, bagels, muffins, cakes, doughnuts and other baked goods.
Wholegrain carbs have their bran and germ intact. The bran and germ constitute the fiber. The fiber applies brakes to the digestive process making the release of glucose from the food a slower process.
The means a gentler release of the glucose into circulation. This prevents the dreaded blood sugar spike and crash that follows. Foods like Amaranth, quinoa, bulgur wheat, oatmeal, brown rice are examples of wholegrain carbs or complex carbs.
Something to bear in mind:
If you are experiencing, blood sugar spikes and crashes, especially frequently, you may want to look into it further.
This is because, blood sugar spikes and crashes may be caused by the following apart from sugar and refined carbs:
- Reactive hypoglycemia
- Stomach surgery that causes food to hasten through to the small intestines
Reactive hypoglycemia, prediabetes can be diagnosed by your medical practitioner. And of course, if you’ve had stomach surgery, then the cause will be obvious to you by now.
So, how do you avoid blood sugar spikes and crashes?
It’s very simple. See image below for guidance.
If you are one of those experiencing the blood sugar roller coaster problem frequently, see your doctor to exclude reactive hypoglycemia and pre-diabetes.
Beyond that, the mainstay of avoiding blood sugar spikes and crashes is to avoiding refined sugar, refined carbs and sweets.
The way to go is to eat complex carbs only. The management of blood sugar spikes and crashes is similar to the management of non-diabetic hypoglycemia. Follow that link as I have more detailed management tips there.
But you can’t go wrong by eating complex wholegrain carbohydrates.
Along with eating complex carbs, include the pulses in your diet. Eat peas, beans, lentils, vegetables and you will experience a steady release of glucose that will keep your blood sugar in the normal zone – the green zone. No spikes. No crashes.
Suggested further reading:
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By Dr Joe
I got a question the other day from one of my readers of this blog. And the question was; how does insulin resistance cause weight gain?
That is a very good question and I will answer it by going back to the basics first.
Let’s talk about how insulin resistance comes about first.
How does insulin resistance happen?
You will recall from my article on high blood sugars in non-diabetics, I talked about how the food, in particular a carbohydrate meal, when broken down to glucose triggers the release of insulin into the blood stream, right?
The idea is to stop the absorbed glucose in the bloodstream from getting too high. The trigger point is 100mg/dl (5.5mmol/l).
Once glucose levels exceed that trigger point, the beta cells in the pancreas will spring into action. The beta cells will release insulin to counter a further rise in blood sugar. That is the first phase insulin release. This happens following food digestion and glucose absorption from the digested food.
If the blood glucose level does not settle, a second wave of insulin is released by the pancreas to complete the job. The interval between the first and second wave insulin release is about 20 minutes.
In a healthy person whose metabolic pathway is well integrated and functioning well, this mechanism of blood sugar regulation works so well that within 90 minutes of commencing your meal, your blood sugar levels will be back to your pre-meal level of around 80mg/dl (4.5mmol/l).
Certainly, by the 2-hour mark, all should be settled on the blood sugar front and life goes on…quietly.
But when you have insulin resistance, life is not quite that simple.
Sadly, there could be a problem further up the blood sugar regulation pathway with insulin resistance.
The liver and muscle cells take up over three-quarters of the glucose sent up the blood stream from the food we just ate.
For the insulin to effectively reduce blood sugar levels, the liver and muscle cells have to be receptive and responsive to allow the glucose from the blood into the cells.
That’s where the problem lies with insulin resistance.
The question then arises. Why do the liver and muscle cells suddenly become unresponsive to insulin signals to allow glucose into them? They were responsive yesterday. What’s happened today?
Well, it’s not an overnight development. Insulin resistance by the liver and muscle cells is a problem that gradually evolves over time.
Eating refined carbs over the years essentially lead to the development of insulin resistance. Excessive refined carbs stimulate large secretions of insulin every time we eat them.
Over time, these liver and muscle cells develop tolerance to the insulin because they are being pounded all the time by insulin to let glucose into them.
Some people eat up to 8 times a day if you include snacking and it is mainly refined carbs we eat.
Each time you eat these foods, you are asking questions of your pancreas and also requesting your liver and muscle cells to respond to insulin signalling.
These cells “get fed up” of being constantly asked to let glucose in. Over time they become tolerant. Which means higher and higher doses of insulin will need to be pumped out by the pancreas to have the same effect.
As a result, the liver and muscle cells become unresponsive to signals from the insulin to allow the glucose inside their cells. They become tolerant. They become resistant!
Just like a drug addict will need higher doses of the abused drug over time as a result of developing tolerance to the drug.
This causes a build-up of glucose in the blood because the liver and muscle cells have ‘shut their doors’ and won’t let the glucose in.
The pancreas compensates by pumping more and more insulin into the circulation causing high levels of insulin in the circulation. This state of affairs is called hyperinsulinemia (high insulin in blood) and it’s not nice…at all.
I will return to the hyperinsulinemia later on because it is the core event that drives weight gain in insulin resistance.
Am I insulin resistant?
Another pertinent question is, how do you know if you are insulin resistant or not. Lots of people are insulin resistant. They just don’t know it. Because there are no tell-tale symptoms of insulin resistance.
Even the symptoms of insulin resistance (if you do experience any) grossly overlap with other common conditions.
That is what makes it difficult to recognise insulin resistance and it can go on for years carefully damaging your health quietly without you being aware of it.
So, are you insulin resistant?
Well, let’s keep things simple, shall we.
If you test your blood sugar on one or more occasions and you are consistently getting results above the recommended acceptable blood sugar levels below, then that should raise a suspicion of insulin resistance.
That’s how simple it is. There are other tests like C-Peptide test and more expensive ones but they are ultimately not necessary to make a diagnosis of insulin resistance.
Alert your doctor if your home blood sugar test following your meals exceed the values below. Your doctor will take things from there. See this article on how to meal-test your blood sugar here.
- Fasting blood sugar should be 100mg/dl (5.5mmol/l)
- 1-hour blood sugar after meals should be 140mg/dl (7.8mmol/l) or less
- 2-hour blood sugar after meals should be 120mg/dl (6.6mmol/l) or less
If your 2-hour after-meal blood sugar is over 200mg/dl (11mmol/l), then you are diabetic. It means your insulin resistance has tipped over to type 2 diabetes.
Within the framework of insulin resistance, there is also what we call metabolic syndrome and below are the diagnostic criteria for metabolic syndrome.
You are eligible to be labelled as having metabolic syndrome if you have 3 or more of the following:
- Waist circumference greater than 102 cm in men and 88 cm in women
- Serum triglycerides level of 150 mg/dL (1.69 mmol/L) or higher
- High-density lipoprotein cholesterol level of less than 40 mg/dL (1.04 mmol/L) in men and 50 mg/dL (1.29 mmol/L) in women
- Blood pressure of 130/85 mm Hg or higher
- Fasting serum glucose level of at least 110 mg/dL (6.1 mmol/L)
How does insulin resistance cause weight gain?
Now that we have the foundational knowledge of insulin resistance, we can now turn our attention to the mechanism behind insulin resistance and weight gain.
Insulin is a fattening hormone. That’s the first thing you need to know.
Insulin is an anabolic hormone. Insulin preserves, builds, restores and conserves.
What insulin isn’t; is catabolic. Never.
When you have a lot of insulin floating around your body, you will constantly be in the anabolic state.
Ask anybody whose been started on insulin hormone by their doctor, they will tell you that without fail, they have gained weight.
More importantly, the weight you gain from insulin is very hard to shift. Weight loss is always frustrating for anyone on insulin therapy.
Evidence that insulin makes you gain weight, apart from anecdotal input from patients on insulin, comes from various studies.
This study for instance took 14 individuals who were taking diabetic pills, switched them from the pills to intensive insulin therapy.
The idea was to demonstrate that blood sugar levels can be brought under control within a specified time frame (in this case 6 months) without the patients developing low blood sugar side effects (hypo symptoms).
It transpired that the researchers ended up using large doses of insulin to reach their objective of controlling the study participants’ blood sugar. This was because the participants had developed insulin resistance.
The researchers did succeed in achieving good control without low blood sugar side effects. But this came at a cost. The study participants gained 8.7kg (19lbs).
Something else to note from that study was that the study participants actually reduced their calorie intake during the study period by a daily average of 300 calories. So, they gained weight across the board despite calorie reduction.
That’s how powerful insulin can be when it comes to fat preservation.
This other study sought to achieve good sugar control on 708 type 2 diabetics who were on diabetic meds by adding insulin to their treatment.
It’s a bigger study compared to the first one above. The researchers did achieve good control but again at the expense of weight gain in the study participants.
There was a proportionate increase in weight gained in line with the dose of insulin received by each study participants. More insulin, more weight gained.
One more study here sought to identify who amongst 50 obese individuals would predictively lose weight and maintain their weight loss through a 6-week calorie reduction regime.
The researchers found that resistance to weight loss and the tendency to regain weight was easily predicted by how much insulin each participant had circulating in their blood.
So, a high insulin level meant you will have difficulty losing weight and even when you did lose the weight, you were more likely to regain the weight within a shorter time frame.
And here’s the kicker:
You’ll recall I said the liver and muscle cells which ordinarily will take up majority of the glucose from the circulation but are resistant to doing so even when prompted by insulin, right?
Well, something else happens that make it possible for someone with insulin resistance to gain weight.
And here it is:
The fat cells also take up glucose from the circulation prompted by insulin but guess what…
The fat cells don’t resist the uptake of glucose. The fat cells welcome the glucose inside them. This would have been a nice gesture except that inside the fat cells, the glucose is stored mainly as fat.
Aha, can you see this generosity of the fat cells is not necessarily a good thing for your weight management efforts when you are insulin resistant.
Essentially, we have a scenario where the liver cells and muscle cells are resisting absorbing sugar from the blood circulation but the fat cells are “happy” to have the glucose where storage in the form of fat is the norm.
Liver and muscle cells are insulin resistant but fat cells are not.
Does this make sense to you now why and how insulin resistance leads to weight gain?
There are a couple of mechanisms at play here that conspire to make you gain weight when you have insulin resistance.
And they are:
Here’s how insulin resistance causes weight gain:
- Your blood insulin levels are high (remember hyperinsulinemia)
- Insulin is undeniably a fat storing hormone
- Insulin is a known predictor of weight gain
- Insulin is a known weight regain facilitator even when you lose weight
- Insulin prevents you from burning up your current fat stores
- Insulin makes you hungry, so you tend to crave refined carbs that further fuels higher insulin levels
- Insulin makes you lazy, so you lack the motivation to exercise
- Your liver cells aren’t keen to absorb glucose from the circulation
- Your muscle cells aren’t keen to soak up glucose from the circulation
- A vicious circle is set up because resistance by the liver and muscle cells leads to high blood sugar which in turn leads to more insulin being secreted by the pancreas further fuelling more resistance and yet more insulin
- Worse still your fat cells will take up sugar from the circulation readily and will store it as fat for you
I thought it would be a good idea to provide you with a diagrammatic illustration of how insulin resistance develops.
So, see image below:
All of those ladies and gentlemen is how insulin resistance makes you gain weight and actually frustrates your weight loss efforts. Not nice!
Suggested further reading:
How to Avoid Complicated Diet Rules and Prevent Rebound Weight GAIN
By Dr Joe
To fully understand what causes high blood sugar levels in non-diabetics, it makes sense to go back to first principles of blood glucose regulation.
You will be glad you did, because by the end of this blog post, you will have the fundamental knowledge to connect all the dots regarding why blood sugar may be high in a non-diabetic.
So, let’s do that, shall we:
Behind your stomach is an organ called the pancreas. The pancreas has a cluster of cells scattered within it called the beta cells.
The beta cells are very important to us. As little in size as they are, their importance cannot be over-emphasized.
Why is this?
Because Beta cells of the pancreas are responsible for producing, storing and releasing insulin when called upon.
You need insulin to survive. Without insulin your cells cannot access the glucose in the blood circulation. Without insulin energy production will cease. Insulin is the hormone that drives sugar from the blood circulation into the cells.
When glucose gets inside the cells, it can then be used by the mitochondria (the power house of the cell) to produce energy. This is the energy we need to perform both basic and advanced everyday activities.
How does insulin interact with the food we eat?
When you eat, digestion of food begins in the mouth. The glucose in the food you eat gets released by the process of digestion via enzymes in your saliva and stomach.
What this means is within a few minutes of chewing your food, blood sugar begins to rise. Of course, the dynamism of this process of digestion varies from food to food.
High glycemic foods will have their glucose released pretty rapidly. Whereas complex carbs for instance are low glycemic in nature. Low glycemic foods will have their glucose released a lot more slowly.
As soon as glucose gets absorbed, it triggers the release of insulin into the circulation to correct blood glucose levels to normal levels.
The trigger point for insulin release is when the blood glucose level hits 100 mg/dl (5.5mmol/l). This is called the First Phase Insulin Release. It is expected that the first phase insulin release should correct the blood glucose level to normal.
Following the first phase insulin response, the beta cells hold back, pause and wait for about 20 minutes to see if blood sugar levels are back to normal.
If this first phase insulin release does not normalize the blood sugar to 100mg/dl (5.5mmol/l), then a second wave of insulin is released by the beta cells of the pancreas to lower the blood sugar level.
This is called Second Phase Insulin Release.
It is also expected that this second wave of insulin release should fix the blood sugar fluctuation back to normal levels.
Physiologically, the combination of the First and Second Phase Insulin release is what prevents blood glucose fluctuations beyond the 140mg/dl (7.0mmol/l) mark.
So, what causes high blood sugar levels in non-diabetics?
Now that you know the dynamics of food digestion, glucose absorption into blood circulation and the expected insulin response, explaining what causes high blood sugar in non-diabetics becomes logical.
So, here it goes:
If you have a fully functioning beta cells in your pancreas that produce, store, and release insulin in response to blood sugar rises when you eat, then a quick response is expected to regulate blood sugar. This quick response prevents unnecessary blood glucose fluctuations.
And this process of blood sugar correction works so efficiently that within an hour and half of eating, your blood sugar levels should return to the fasting blood sugar levels of below 100mg/dl (5.5mmol/l).
In fact, at 2 hours after-meal, both the first phase and second phase insulin release from the beta cells should have your blood sugar levels down to 80mg/dl (4.5mmol/l).
However, if your First phase insulin response and more importantly, your Second phase insulin release is defective or sluggish for whatever reason, then you will have high blood sugar level even if you are non-diabetic. This is actually referred to as Impaired Glucose Tolerance.
Persistent impaired glucose tolerance is actually pre-diabetes.
Impaired glucose tolerance precedes Type 2 diabetes. If your blood sugar level remains high despite your first and second phase insulin release best efforts, such that it hits 200mg/dl (11mmol/l) 2 hours after eating, then by definition, you are now diabetic.
Insulin resistance in the making – How does insulin resistance occur?
Your liver cells and muscle cells take up over three-quarters of the glucose produced by your meal. When your beta cells release insulin, the insulin drives the sugar from the blood circulation into the cells.
It is anticipated that the liver and muscle cells should be very responsive to the prompt by insulin to allow glucose inside those cells under normal circumstances.
The more responsive the cells are the more insulin sensitive you are.
However, there is a situation where even though your beta cells show a good first phase response, the amount of insulin released will not be enough to clear the circulating glucose from the blood.
This is because of what is happening peripherally in the receiving target organs – the liver and muscles.
The cells of the liver and muscles become stubborn. They become unresponsive to the insulin released. The liver and muscle cells are resistant to the signals from the insulin to allow the glucose into them.
What happens next is that the second phase insulin release is prolonged. The second phase response is prolonged because the beta cells have to make and release lots more insulin to force a response by the resistant liver and muscle cells.
This lack of response by the liver and muscle cells to allow glucose inside their cells despite a persistent prompt by insulin is described as insulin resistance and is indeed how insulin resistance occurs.
At this stage of the metabolic disturbance, you end up with high levels of insulin circulating in your blood. This is the result of the pancreas working overtime to drive down the elevated blood glucose by secreting lots more insulin.
This is called hyperinsulinemia.
If you have insulin resistance, you most certainly will have high circulating levels of insulin in your blood (hyperinsulinemia).
Why have the liver and muscle cells become unresponsive to insulin?
It is a tolerance issue. Eating refined carb meals for years leads to heavy demand on the pancreas. The pancreas does its job perfectly in the preceding years.
But refined carb meals always need lots of insulin to restore blood sugar to normal. And in the preceding years, your liver and muscle cells always respond positively by letting sugar into them.
However, as the years roll by and our diet remains unchanged, the liver cells and muscle cells become tolerant to the insulin. They therefore become unresponsive due to the tolerance they have developed.
Meaning they’ve become resistant!
And this insulin resistance is the reason your blood sugar is high as a non-diabetic. Because at this stage, your blood sugar is high but hopefully not high enough for you to be classified as a diabetic.
Insulin resistance may persist undetected for a good number of years. Most times insulin resistance may last up to a decade and even beyond. During all of this time, it will remain undetected and you will to all intents and purposes consider yourself as non-diabetic.
In the end, the beta cells will become exhausted and unable to produce enough insulin to drive down the glucose to normal levels. Blood glucose remains persistently high ultimately leading to Type 2 diabetes.
You may be somewhat “lucky” such that you grow new beta cells that will make and store enough insulin to use in the first and second phase insulin release. But you won’t make enough insulin to lower your blood sugar to normal levels within the usual time frame.
The second phase might take a lot longer.
However, your beta cells will make just enough insulin to stop you drifting into the ‘diabetic zone‘ but not enough to normalize you blood sugar. What that means is; you remain stuck in the ‘impaired glucose tolerance’ stage.
This results in metabolic syndrome. Metabolic syndrome is synonymous with insulin resistance. In fact, metabolic syndrome is also known as insulin resistance syndrome.
In a nutshell, high blood sugar in a non-diabetic can be innocuous when it occurs transiently.
However, frequent and persistent high blood sugar in non-diabetic is not that innocent and can be attributed to:
- Some failure at the level of the pancreas to efficiently produce and release enough insulin
- Failure of the liver and muscle cells to respond to insulin signalling.
In essence, high blood sugar in a non-diabetic especially when it occurs frequently is likely due to insulin resistance or metabolic syndrome and later on with the build-up of higher blood sugar Type 2 diabetes becomes inevitable.
What foods can cause high sugar in non-diabetic?
Below is a list of foods that can cause your blood sugar to be high even if you are non-diabetic:
- Sports drinks and energy drinks
- Black tea
- Dried fruits
- White bread
- Potato chips and fries
- Green tea
- Chinese foods
- Regular pasta
- Yogurt with added sugar
- White rice
- Baked potato
- White chocolate
- Soda and other fizzy drinks
- Fruit juices
- Certain fruits like pineapple, dates, watermelon
Of course that list is by no means exhaustive.
What causes blood sugar to rise without eating?
For the most part, food as you gathered from above, is the main driver for rises in blood sugar. However, life as you know is never a straight line.
There are other factors that can cause blood sugar to rise without eating. Some of that has to do with inter-play of hormones.
Stress hormones like cortisol, catecholamines (adrenaline and noradrenaline), mobilize glucose from the stored glucose in the liver. Glycogen is the stored form of glucose in the liver.
These hormones cause a rise in blood sugar without eating both in diabetics and non-diabetics. Any thing that causes stress to your body will cause your blood sugar to rise.
Prescription and some over-the-counter medications like nasal decongestants can also cause your blood sugar to rise without eating.
Below are some of the causes of high blood sugar without eating:
- Steroid medication
- Stressful job
- Diuretics – pills that make you pee
- Nasal decongestants containing phenylephrine or pseoudoephedrine
- Poor sleep
As you tell from the above list, yes, stress can cause high blood sugar in non-diabetics. Stress from whatever origin has the potential to increase cortisol levels in the blood.
And as I explained earlier anything that causes liver cells to mobilize their glycogen stores unnecessarily will raise your blood sugar. Stress will do just that.
Should non-diabetics check blood sugar?
If you’ve read this far, you will have figured that non-diabetics can have blood sugar spikes without the individual being aware of it. And non-diabetics may have raised blood sugar for years without being diagnosed as having raised blood glucose issues.
Your doctor may not suspect you have blood sugar regulation problems unless you have symptoms. Sadly, lots of people stay in the ‘Impaired Glucose Tolerance’ zone for years without symptoms.
That’s the reason at least a third of the adult population are going about their business without actually realising they have insulin resistance. Only the eagle-eyed amongst us will exclude themselves from this raging scourge.
And Guess what…
The best way to ensure your high blood sugar as a non-diabetic is not a fluke but a much more serious condition like insulin resistance is to test yourself for blood sugar level when you eat.
So, yes, my advice is that non-diabetics can test for blood sugar, if you are looking for some guidance on the matter.
You can just do random blood sugar 1 hour and 2 hours after a meal and see where you stand metabolically speaking.
I have a more detailed technique of doing this. It’s called Eating To Your Meter. Go see it on that link. I have it written there in a step-by-step way for easy digestion (no pun intended).
Yes, test your blood sugar even if you are non-diabetic. Your doctor probably won’t do it as you have no symptoms. Someone’s got to…
Suggested further reading:
3 Unique Veggies That Fight Abdominal Fat?