The most important factors that influence development of the eye, kidney, and nerve complications of diabetes are the duration and degree of exposure to hyperglycemia. Hypertension is also very important. The risk of complications appears to be similar for all patients with diabetes; differences in complication rates between patients with type 1 and type 2 diabetes are largely due to differences in duration of diabetes and glycemic control. The benefits of lowering blood sugar are also similar for patients with diabetes, regardless of the type. Significant reductions in complications can be seen with relatively short-term treatment of hyperglycemia.