Insulin resistance appears to have a major effect on heart disease. Work at Stanford Medical Center, the University of Buffalo Medical Center, and other medical research facilities have pointed to the higher incidence of CHF (Congestive Heart Failure) amongst patients with insulin resistance. Congestive Heart Failure is a rapidly-growing healthcare problem in the United States, with over five and a half million people suffering from the consequences of an inefficient, enlarged heart. Many in later stages are unable to walk or even get out of bed.

CHF can come from many sources, but insulin resistance is an independent causative factor which does not depend on lack of exercise or obesity to cause its damage to the heart and circulatory system.

How does insulin resistance affect heart health? The answer is difficult, as it is tied to complex interactions between various hormone levels and the reaction of organs to chronically higher levels of insulin in the blood. Those who have insulin resistance tend to have other factors (or 'co-morbidities') which, taken on their own, also increase the dangers to the heart and circulatory system.

For example, patients with insulin resistance also have lower levels of HDL (high-density lipids), the 'good' cholesterol which is associated with fewer heart attacks, and higher levels of LDL (low-density lipids), which are associated with artery-clogging plaque. They also tend to have higher blood pressure, another heart risk factor.

What lies behind these greater co-morbidities, and resultant risk for patients? Androgen levels were found to be higher in patients with insulin resistance, and androgen is the male hormone that is associated with stress and increased heart disease. Just as estrogen seems to have some heart-helping qualities, androgen has some inhibitors to heart health, both by diminishing estrogen levels and increasing stress-related inflammation.

In addition to the hormonal effects, high insulin levels in the blood over a longer period of time can lead to breakdowns in organs, particularly those sites in the body where changes arteries and capillaries can result in food and oxygen starvation. Diabetics are generally known to have higher incidences of heart disease, but they are also much more likely to have problems with lower leg circulation (because the blood circulates particularly slowly in the legs), vision (because of the network of small capillaries in the eyes, which are subject to blockage) and peripheral vascular systems, such as kidneys and the carotid arteries.

Recent work in Canada points to the effect of insulin resistance on inflammation and associated plaque production. Plaque is implicated in a number of diseases, including that which causes 'silent' heart attacks in individuals who seem healthy. The effect of insulin resistance on plaque formation could be a primary one, or a secondary effect from other hormonal and metabolic changes in the body related to cholesterol levels and inflammation.

The overall conclusion in early research is clear. Insulin resistance poses problems to the body directly, through influence of high levels of insulin to critical organs, and indirectly, through influence on the secretion of other hormones and inflammatory substances which can lead to heart disease. While many diabetic patients are insulin-resistant, and diabetic patients tend to have much higher rates of heart disease, insulin resistance in itself poses an increased risk of complications for patients.