There are several reasons why the risk of vascular diseases, such as heart attack, stroke, and diseases of the vessels in the limbs (peripheral vascular disease), is increased in both types of diabetes. The weight gain and lack of exercise common in people with type 2 diabetes lead to other conditions such as abnormal cholesterol levels and high blood pressure, which are potent causes of vascular disease. If all of these risk factors are not treated effectively, the probability of vascular disease remains high.
High blood sugar over months and years leads to a chemical reaction of the sugar in the blood vessels, damaging them structurally. Perhaps most importantly, we now know that diabetes and obesity can be described as irritants to the body tissues, meaning that the body becomes generally inflamed. We know that this is so because we can measure high levels of com-pounds that indicate inflammation in the blood of many people with diabetes. It turns out that this inflammation, when maintained over time, extends to the lining of the blood vessels, which attracts inflammatory cells out of the bloodstream. Cholesterol also takes on an inflamed form, enters the lining of the blood vessels, and attracts still more inflammatory cells from the bloodstream, setting the stage for serious damage.
Other contributors to vascular disease include the fact that high blood pressure results from nephropathy, which further damages blood vessels. This further damages the kidney and blood pressure rises still further, setting up a vicious cycle. Even short periods of high glucose, such as may occur after meals in people with diabetes and even prediabetes, can cause problems with the function of blood vessels, making them more sticky, inflamed, and less able to relax. Whether these repeated briefer periods of high blood sugar combine over time to cause permanent vascular dam-age is not known. However, it is known that the risk of vascular disease is already high in people with prediabetes.