Diabetic angiopathy--its lessons in vascular physiology.

Progress in our understanding diabetic angiopathy has been slow, but we are now learning a number of lessons of interest to the cardiologist. Diabetic angiopathy is a collective term for conditions specific to the diabetic state and related to its duration more than to patient age. The angiopathy produces calcification of the media of larger arteries, but its major effects are in the microcirculation. Intense interest in one feature, skeletal muscle capillary basement membrane thickening, has dominated the last decade. Capillary basement membrane thickening, while characteristic of diabetes, is associated with little direct impairment of the microcirculatin. It appears to play no role in the pathogenesis of diabetes itself. The pathology of diabetic retinopathy and diabetic nephropathy suggests that arteriolar changes may be the major mediator of diabetic angiopathy. This concept is supported by the interactions between hypertension and diabetes in the eye and kidney. The course of diabetes of youthful onset differs from that of maturity onset. The relative frequency of diabetic angiopathy is higher, and of atherosclerotic complications is lower. This has made it difficult to demonstrate the potential value of preventive measures. Benefit to one type of problem may become hidden by worsening of the other. If the diabetic benefits from what is learned about how ischemic heart disease risk can be reduced, he will require even more effective management to prevent or control diabetic angiopathy.