Heart in Diabetes: A Microvascular Disease

D iabetes currently affects about 5% of world’s populations, and its prevalence is rapidly increasing particularly in elderly subjects. Because over 80% of all diabetic subjects have type 2 diabetes, the increase in the number of individuals with diabetes implies an epidemic of type 2 diabetes. Diabetes is associated with hyperglycemia-specific microvascular complications. Furthermore, macrovascular complications, especially coronary artery disease (CAD) but also stroke and peripheral vascular disease, are increased by twoto fourfold in type 2 diabetes. Cardiovascular disease (CVD) is the most important long-term complication and by far the greatest cause of death in people with diabetes. In fact, over 50% of all patients with type 2 diabetes die of CAD (1). Although much of the excess risk of CAD among patients with diabetes is accounted for by the presence of diabetesassociated CVD risk factors such as LDL cholesterol, elevated blood pressure, and smoking, a substantial proportion remains unexplained. A deleterious effect of the diabetic state on vascular and endothelial function is likely to be important via its ability to increase the potential for vasoconstriction and thrombosis. In population-based studies, the relationship of hyperglycemia to CAD is evident but the association is less strong than that of LDL cholesterol and elevated blood pressure. There is also evidence that the role of hyperglycemia with respect to the risk of CVD is larger among patients with type 1 diabetes than in patients with type 2 diabetes. In our study, an increment of 1 unit (%) of glycated hemoglobin increased CVD mortality by 52.5% (95% CI 28.4–81.3) in patients with type 1 diabetes and by 7.5% (4.3–10.8) in patients with type 2 diabetes (2). CAD also includes a microvascular component. Diabetic cardiomyopathy, a relatively rare condition, associates with the presence of microvascular complications in diabetes. Therefore, changes in small arteries and capillaries are not only responsible for microvascular long-term complications, but also for other manifestations of heart disease in diabetes.