There is substantial evidence that hyperglycemia does play a role in the development of long-term complications, although a genetic predisposition to these complications seems to be important. Also the literature seems to suggest that the degree of hyperglycemia correlates well with both the severity and incidence of long-term complications. However, looking at recent studies in the attempt to answer the question of "can we prevent or minimize complications," we must conclude that there is no definitive evidence that the typical long-term complications of microvascular or macrovascular disease can be prevented with tight control. Hopefully, the current study under way at the NIH will help clarify this issue. It seems likely after reviewing all the evidence that future studies will show tight control to be beneficial. The clinician must weigh the costs of tight control against the potential benefits, particularly in the type II diabetic. It seems prudent to strive for the best control that can be achieved within the confines of the patient's resources, to pay meticulous attention to all factors contributing to complications, such as hypertension and smoking, and to avoid subjecting the patient to undue risks.