There’s always a surprise around the corner when it comes to our health. Insulin resistance and high blood pressure is one. Is there a relationship between insulin resistance and high blood pressure?
Okay, let’s get direct. Does insulin resistance cause high blood pressure? Let’s explore that question on this page. This is very important because it constitutes part of the spectrum of the metabolic syndrome. A syndrome that is making us sick the world over. Worse in the Western hemisphere.
So, does insulin resistance cause high blood pressure?
The simple answer to that question is: Yes, insulin resistance does cause high blood pressure. In fact, the relationship is so strong that some scientists now believe that what we call ‘Essential Hypertension’ should no longer be called that.
Because we now have a cause for that high blood pressure of indeterminate origin. Insulin resistance.
In case you didn’t know, essential hypertension is hypertension (high blood pressure) for which there’s no known cause.
But now we know essential hypertension is not neccessarily without a cause. It has a cause that has been missed all of these years. Insulin resistance is the cause of most essential hypertension cases.
If you have any doubt, ask your doctor the next time you visit him/her, if most people with type 2 diabetes also have high blood pressure. Your doctor will probably smile at you and will answer in the affirmative.
Yes, a relationship exists between hypertension and glucose intolerance without doubt.
What’s the background to insulin resistance and high blood pressure relationship?
Here’s the background.
The first thing to remember is that when you have insulin resistance, your insulin levels in the blood are going to be persistantly high. The reason is that your pancreas will keep pumping insulin into circulation to overcome the resistance of the cells to respond to insulin action.
Insulin’s primary job is to drive glucose out of the blood circulation into the cells of our body where the glucose is needed for energy production. In insulin resistance, the insulin receptors which are the “doorman” guarding glucose entry into the cells become desensitized.
Once desensitized, they are no longer responsive to signals to let glucose into the cells. The result is high blood glucose levels. This triggers further release of insulin from the pancreas as a compensatory mechanism. The idea being to lower blood glucose levels at all cost.
And because the insulin receptors on the cells are not “listening” to these signals, the result is higher and higher levels of insulin in the blood circulation. A sort of reactive hyperinsulinemia, if you like.
Imagine the pancreas as a pump station. It will keep pumping insulin until the blood sugar levels drop. Unfortunately those high levels of insulin in the blood circulation through a cascade of events result in high blood pressure.
This study was able to reproduce the effect of insulin on blood pressure when it observed a rise in blood pressure in patients commenced on insulin therapy. Meaning the presence of insulin through insulin shots is enough to trigger a rise in blood pressure.
There’s even a suggestion that high insulin levels especially high fasting insulin levels play a huge role in the development of high blood pressure independent of weight.
Highlight: Insulin resistance always carries the inescapable misfortune of elevated insulin levels (hyperinsulinemia). It is the hyperinsulinemia that forms the bedrock of the unhealthy relationship between insulin resistance and high blood pressure.
So, how does insulin resistance cause high blood pressure?
There are 3 possible mechanisms. And they are all related to the high insulin levels.
Mechanism #1 – Insulin resistance and the autonomic nervous system
The first is that; high insulin levels in blood drives sympathetic activity. If you have high blood pressure, the last thing you want is high sympathetic activity of your autonomous nervous system. Not good.
The sympathetic nervous system raises blood pressure. That’s a direct response and is bad for your health. Someone with high blood pressure should be hankering for what I decsribe as ‘Parasympathetic Domination‘.
For instance, if you were confronted by a lion. The sympathetic nervous system will automatically take control. It is needed in that instance to protect you. For self-preservation, if you like. It automatically prepares you for the ‘Fight or Flight response‘.
But there are other instances where the action of the sympathetic become undesirable. High blood pressure is one of them. With high blood pressure, the parasympathetic nervous system is a better friend to you.
Highlight: The pressor effect exerted through the sympathetic nervous system narrows your blood vessels mainly the arteries resulting in higher blood pressure. Not good!
Mechanism #2 – Insulin resistance and the kidney effect
High insulin levels has an effect on what happens in your kideneys as urine is being formed. Normally the kidneys have a fine balancing act where they control how much Sodium is retained in the body and how much is expelled out of the body through urine.
This fine balancing act is influenced by a couple of substances in particular Aldosterone. This is done through a well co-ordinated system called the Renin-Angiotensin-Aldosterone System (RAAS).
But it would appear that when insulin levels are high, insulin gets in on the action too. Insulin influences what happens in the kidneys at high levels.
What does insulin do in the kidneys?
Insulin levels when high, facilitates retention of sodium in the body through the RAAS.
The overriding influence of insulin on the Renin-Angiotensin-Aldosterone (RAAS) is extensively reviewed here and here.
In fact, the relationship between insulin resistance and high blood pressure is so close that the class of blood pressure medications called ACE inhibitors like Lisinopril, Ramipril and the ARB medications like Valsartan, Losartan, Candesartan are thought to actually improve insulin sensitivity.
Mainly because those class of medications block the RAAS mechanism at various points which in turn reduces the influence of insulin.
This the second mechanism through which insulin resistance causes high blood pressure.
Highlight: The net effect of sodium and water retention in the body is high blood pressure.
Mechanism #3 – Insulin resistance and your arteries
Persistent high insulin levels almost ineveitably leads to lipid dysfunction. Dyslipidemia is one of the hallmarks of metabolic syndrome.
Why is this?
Quite simply; insulin is a fat storing hormone. Insulin facilitates the storing of fat both viscerally and underneath the skin too. Along with that is the elevation of triglycerides and LDL cholesterol.
Over time, high lvels of LDL cholesterol (the bad cholesterol) and triglycerides, results in hardening of arteries. When arteries are hardened, they become inelastic.
If your arteries are in elastic, they are less stretchy, less relaxed. Blood pressure goes up because of the inelasticity. Obviously if the situation is allowed to prgoress unchecked, plaques will form in the arteries making the situation worse.
Highlight: High insulin level is bad for the health of the walls of your arteries. Insulin is in fact, atherogenic.
What should you do?
As I stated in the video above, if you have high blood pressure, it makes sense to screen yourself for insulin resistance. The relation between insulin resistance and high blood pressure is so strong that screening yourself is best thing you can do for your health.
You should assume that if you have high blood pressure, then you probably have insulin resistance until proven otherwise. Act on the basis of that premise.
Ideally you would want to check your blood fasting insulin levels but such a test is beyond the reach of most of us.
So the best alternative is to check your fasting blood sugar levels. It’s very simple to do. All you need is a blood sugar monitor.
One of the queries I get often on this blog is: does drinking water reduce blood pressure? If we flip that question on its head, the question can be framed differently.
What will that be? It will be: does dehydration affect blood pressure?
I shall answer both questions for you on this page and you shall know the truth regarding water and blood pressure reduction.
Plus, you also get to know briefly the importance of water to our bodies, why we need water, how much water to drink and the effect of over-consumption of water on blood pressure too.
And you get my recommendation on the best drink for high blood pressure.
The way I am going to approach the subject is this. I will discuss the effect of dehydration on blood pressure first, then talk about how drinking water (rehydration) affects your blood pressure afterwards.
Kinda make sense to do it that way.
But if you’re in a hurry and only want to know if drinking water reduces blood pressure, then you can scroll towards the later part of this article for an answer straightaway.
Using water as a blood pressure remedy can seem a little far fetched but there’s some truth in it, within reason.
I know that some people do take it a little too far. I have read some people claim that drinking just water only without any medications whatsoever lowered their blood pressure and now they live life happily ever after.
We live in a world where anyone can make any claim regarding anything. This is worse online. After all, people make all sorts of claims about diabetes and cancer online. These claims range from the sublime to the ridiculous.
So, it’s not surprising we have people making ridiculous claims about blood pressure treatment at home…and even low blood pressure.
Before I delve into the possibility of dehydration causing high blood pressure and the fact that drinking water is one way you can lower your blood pressure naturally, let’s talk about the importance of water to our bodies briefly first.
How important is water to our bodies?
Well, make no mistake about it. Water is very important to our very survival. Without water we won’t be here on this planet.
This is exemplified in the fact that the average adult body is made up of 55 – 60% water. Babies have even more water content in their bodies. Babies are made up of 75% water until they are 1 year old when their water content drops to 65%.
Water plays a huge role in our bodies. From joint lubrication to keeping our brain well hydrated. Your brain is 75% water, believe it or not. Our brains have the same amount of water as you’ll find in ripe bananas. Our lungs are to a large extent a wet organ too.
Let’s not forget body temperature regulation. Water plays a major role in heat generation for our bodies.
In fact, without water, there will be metabolic mayhem in our bodies. Undoubtedly so.
Why do we need to drink water daily?
We need to drink water daily because some of our body functions mean we lose water every day. We lose water through urine. We lose water through bowel movement. We lose water through sweat. We lose water through our breathe.
All of that water loss needs to be replaced.
If we fail to replace the water lost through those bodily functions, dehydration will result.
But there has to be a fine balance between how much we are losing and how much we replace.
This fine balance prevents dehydration and over-hydration. Both over-hydration and dehydration are bad for our health.
Indeed, too much water in the body from over-hydration is just as bad for our blood pressure as dehydration is.
So, does dehydration affect blood pressure?
Yes, it does. And dehydration does affect blood pressure through 3 different mechanisms.
Dehydration is a potent trigger for a whole host of metabolic events.
Let’s just talk about hormonal events that occur when you are dehydrated. Because this is how dehydration can affect your blood pressure.
The 1st Dehydration-BP Elevation Mechanism
Dehydration leads to renin secretion. Renin is an enzyme produced in the kidneys in response to low blood volume or low salt levels in the blood.
When renin is released, it triggers the conversion of another pro-enzyme called angiotensinogen to angiotensin 1.
A chain of events follows. I don’t want to bore you with the details. All you need to know is that; the end result of that chain of events is the production of another hormone called aldosterone.
The job of aldosterone is to conserve the mineral called sodium. Of course, wherever there’s sodium, water follows. Aldosterone raises blood pressure as a result.
Aldosterone raises blood pressure by preventing the kidneys from losing sodium in urine. Conserve as much sodium as possible.
And because water follows the sodium saved by the aldosterone (don’t forget that sodium is salt), our blood pressure gets elevated when we are dehydrated.
Blood pressure rises when salt and water are retained in the body.
This chain of events caused by dehydration is initiated by renin. In fact, this research tells us a 24-hour episode of dehydration induced a 3-fold increase in renin activity in the body.
That’s the power of water deprivation with a ripple effect on our blood pressure.
That’s one mechanism.
The 2nd Dehydration-BP Elevation Mechanism
A second mechanism of how dehydration can affect our blood pressure is via another hormone called Anti Diuretic Hormone (ADH).
ADH is released from the hypothalamus in our brain when dehydration signals are received by the brain.
Anti Diuretic hormone as the name implies stops you losing water in urine. Meaning ADH will concentrate your urine to conserve water in the body.
By reducing the amount of urine excreted by the kidneys, blood volume increases and blood pressure rises as a conseqence. This is a protective mechanism to prevent the fatal consequences of dehydration on your body.
This action in turn will elevate your blood pressure too.
The 3rd Dehydration-BP Elevation Mechanism
There’s a 3rd mechanism through which dehydration elevates your blood pressure. It involves a direct effect on the tiny vessels we call capillaries.
Dehydration causes these capillaries to “narrow up”. When these tiny vessels become narrow, the pressure inside them rises causing a blood pressure elevation.
So, whereas initially dehydration leads to a lower blood pressure, compensatory mechanisms move things in the opposite direction leading to high blood pressure.
That’s how our body protects itself from harm caused by dehydration.
So, does drinking water reduce high blood pressure?
Yes, drinking water does reduce high blood pressure but with a caveat. You only need to drink what your body requires for the effect of water on blood pressure to be within the safe margins.
You just need to stay well hydrated. Nothing more.
The reason water does cause a reduction in blood pressure is the reverse of the events I discussed above.
Staying well hydrated by drinking plain water, mineral water or decaffeinated tea means you suppress renin release. Inhibiting the release of renin means you avoid elevated aldosterone levels.
Remember I said, aldosterone causes blood pressure elevation, so we don’t want to trigger its release.
We also want to suppress Anti Diuretic Hormone release by drinking enough.
Drinking enough water staves off those hormonal events that lead to blood pressure rise. Meaning drinking adequate water helps us lower high blood pressure naturally.
The effect of drinking water to lower or reduce blood pressure may not be as dramatic as eating foods that lower blood pressure quickly, but it helps a great deal.
What about over-hydration…
Does drinking too much water cause high blood pressure?
If you remember, I did say, to use water as a natural blood pressure remedy, you only need to drink enough to stay well hydrated.
This means you don’t need to go over-board because drinking too much water can actually cause high blood pressure.
It’s got to be finely balanced.
What’s the fine balance?
How much water should I drink a day?
Well, conventional teaching has always been that we should aim to drink 8 glasses of 8-oz glass per day.
But that advice is changing.
The amount of water we need to drink a day largely depends on our weight and our environment.
The recommended daily water intake does vary but it ranges from 2.5 liters – 3.7 liters for men and between 2 liters – 2.8 liters for women.
Obviously, that recommended daily water intake is not set in stone. Our daily water intake can be dialled up or down depending on how healthy we are, how old we are, how active we are and how hot the environment we are located is.
So, drink enough water or decaffeinated beverage like tea or mineral water or even coconut water to stay hydrated but don’t overdo it.
Because when you drink too much water especially within a short time interval, you can cause salt dilution in the body.