Heart Disease in Diabetes - How to Prevent it : Dr. Zaidi

Heart disease in diabetes is highly prevalent. In fact, many diabetics have already developed heart disease by the time they become aware that they have diabetes.

Table of Contents

What Causes Heart Disease in Diabetes

The root cause for heart disease in Type 2 diabetes is Insulin Resistance and inflammation. In this way, heart disease and heart attacks are preventable, but only with proper evaluation and treatment of Insulin Resistance and inflammation.

The risk factors for insulin resistance are: abdominal obesity, high blood pressure, low HDL cholesterol, high triglycerides, and Pattern B LDL cholesterol.

An elevated CRP (C-reactive protein) level on the blood test is a marker for inflammation and is frequently present in Type 2 diabetes. It indicates a high risk for heart disease in diabetes.

High Levels of Insulin Causes Heart Disease In Diabetes

When you have insulin resistance, your level of insulin goes through the roof to compensate for the resistance to the action of your own insulin. Higher than normal level of insulin is not good. Because it stimulates the growth of the muscle cells in the walls of the coronary arteries, which causes thickening and stiffness of the arterial walls. This process ultimately leads to narrowing and hardening of the coronary blood vessels, which is called arteriosclerosis.

High Blood Pressure Contributes To Heart Disease In Diabetes

High blood pressure, a component of IRS, is present in most Type 2 diabetics, and is known to cause narrowing of the arterial blood vessels, including arteries of the heart. Blood pressure higher than 120/80 mm Hg increases your risk for a heart attack. A healthy blood pressure is less than 120/80 mm Hg in most individuals, as long as you don’t have dizziness. However, in the elderly, aggressive lowering of blood pressure is not desirable, as long as blood pressure is less than 140/90.

High insulin levels, due to insulin resistance, causes high blood pressure by the following mechanisms:

An increase in insulin level causes thickening of arterial walls, which then become stiff. Increased resistance to blood flow through the stiff blood vessels leads to an increase in blood pressure.

High insulin level causes retention of sodium and water from the kidneys, which then leads to high blood pressure.

An elevated insulin level stimulates the sympathetic nervous system, which causes constriction of blood vessels, which then leads to high blood pressure.

High Triglycerides and Low HDL Cholesterol: Major Factors For Heart Disease In Diabetes

Most Type 2 diabetics have a high level of triglycerides and a low level of HDL (good) cholesterol, both of which are components of IRS.

Why Diabetics Have High Triglycerides?

In healthy individuals, one of the functions of insulin is to suppress the breakdown of fat from the fat cells into the blood stream. This action of insulin is hampered in individuals with insulin resistance. As a result there is an exaggerated breakdown of fat from the fat cells. The product of this fat breakdown is called free fatty acids. Thus, in diabetics with insulin resistance, there is a high level of free fatty acids in the blood. The liver takes up these free fatty acids and converts them into VLDL cholesterol (very low density lipoproteins). These cholesterol particles are rich in triglycerides, which is why individuals with insulin resistance have a high level of triglycerides.

Why Diabetics Have Low HDL Cholesterol?

When VLDL particles interact with HDL particles, VLDL exchanges its triglycerides for the cholesterol of HDL particles. This results in a decrease in HDL cholesterol. These Triglycerides-enriched HDL particles also break down easily, which lowers HDL level. This is how most Type diabetics with insulin resistance end up with low HDL cholesterol.

HDL cholesterol works as a scavenger by cleansing out the cholesterol deposited in the walls of blood vessels. That is why HDL cholesterol is known as the “good” cholesterol. If your HDL is low, there will be less cleansing of the cholesterol buildup in the vessel wall. Therefore, a low level of HDL cholesterol is a major risk factor for narrowing of coronary blood vessels.

VLDL particles also give rise to the formation of another cholesterol particle known as IDL (intermediate density lipoprotein), which then converts to LDL (low density lipoproteins). VLDL, IDL, and LDL particles deposit in the arterial wall, which causes narrowing of the vessel wall.

Pattern B LDL Cholesterol Causes Heart Disease In Diabetes

LDL (bad) cholesterol consists of two subpopulations:

Large, fluffy particles (Pattern A)
Small, dense particles (Pattern B)

Pattern B particles are small and dense. Therefore, these particles – acting like bullets – deposit more easily inside the blood vessel wall. In comparison, Pattern A particles are large and fluffy and float around inside the lumen of the blood vessels. And tend not to penetrate into the wall of the blood vessels. For this reason, Pattern A particles are not as dangerous.

In Type 2 diabetic patients with insulin resistance, there is a predominance of the more harmful Pattern B particles. Subsequently, there is build up of plaque inside the coronary blood vessels.

High Risk for Clot Formation

In Type 2 diabetics with insulin resistance, there is a high level of several clotting factors, including fibrinogen levels in the blood, which increases the risk for blood clot formation. In addition, these patients also have a decreased ability to break up blood clots. This happens due to a high level of a substance known as PAI–1, short for plasminogen activator inhibitor-1.

Consequently, Type 2 diabetics are at a high risk for blood clot formation and have a decreased ability to break up these clots. When a clot forms in an already narrowed coronary blood vessel, a person might suffer an acute heart attack.

An Elevated CRP Level Increases Risk For Heart Disease In Diabetes

A high level of highly sensitive CRP (C-Reactive Protein) indicates ongoing inflammation in the blood vessel wall. Inflammatory cells are present in the atherosclerotic plaque inside the blood vessel wall. When inflamed, these plaques can easily rupture. A ruptured plaque attracts clotting factors. A blood clot forms at the site of a ruptured plaque, which then causes an acute shutdown of blood flow that may result in an acute heart attack. A high level of CRP, therefore, indicates a significantly higher risk for a heart attack. Type 2 diabetics with insulin resistance usually have a high level of CRP.

Endothelial Dysfunction

The endothelium, the lining of the blood vessel wall, produces a number of substances, a balance of which is important for its healthy functioning. A number of these substances can cause constriction of the vessel wall (vasoconstriction), while others cause a dilatation of the vessel wall (vasodilatation).

In healthy individuals, there is a fine balance between these two processes. Type 2 diabetics with insulin resistance have a disruption in this balance in such a way that there is more vasoconstriction and less vasodilatation. This endothelial dysfunction causes further narrowing of the blood vessels.

Heart Disease in Diabetes Even After Angioplasty

As all of the above indicates narrowing of coronary blood vessels is a complex process. It develops over a period of years due to underlying Insulin Resistance Syndrome and low grade inflammation.

To recap, the process of narrowing of the coronary arteries consists of:

Deposition of cholesterol in the wall of the coronary arteries

Proliferation of a variety of cells in the wall of the coronary arteries

Damage to the lining of the coronary arteries (endothelial dysfunction)

Angioplasty, as well as stent placement, temporarily opens up the narrowed blood vessel, but has no effect on the cholesterol buildup inside the wall of the blood vessel. Hence, after an angioplasty, if appropriate drug therapy is not instituted to treat the disease process inside the wall of the blood vessel, it will shut down again. An angioplasty is a temporary fix. It must be followed by aggressive drug treatment of the underlying disease process.

Heart Disease in Diabetes Even After Heart Bypass Surgery

An acute heart event, such as chest pain, brings patients to the hospital and to the likely diagnosis of a narrowing of the coronary arteries. Usually, they undergo angioplasty, stent placement, and/or heart bypass surgery. These procedures are only temporary solutions to relieve an acute emergency situation and don’t treat the underlying cause of the problem: Insulin Resistance Syndrome. Unfortunately, even at this stage, most patients are not diagnosed with Insulin Resistance Syndrome. Patients think their problem is fixed and they’ll be fine as long as they eat right, and take their drugs to lower cholesterol.

As demonstrated above, the process of Insulin Resistance Syndrome and, consequently, narrowing of the blood vessels continues until one day they are again rushed back to the hospital with chest pain only to find they are having another heart attack. Even after heart bypass surgery, it’s essential to treat the real cause of narrowing of the coronary arteries — Insulin Resistance Syndrome.