Advances in diabetes for the millennium: chronic microvascular complications of diabetes.

Hyperglycemia and microvascular complications of retinopathy, nephropathy, and neuropathy are shared by type 1 and type 2 diabetes. These complications seem to be uniquely associated with the diabetic state in humans and animals; they are not seen in nondiabetic humans or animals. Intervention trials aimed at achieving lower blood glucose levels as reflected in a lower HbA1c value have shown reductions in the rate of development of those complications when HbA1c is lower in one group compared with a matched group with less good control. Currently, 3 schools of thought have been championed to explain elevated blood glucose. Each is discussed here, as are interventions aimed at the various metabolic derangements rather than at correction of the hyperglycemia.