OBJECTIVE - The main of the study of 153 male veterans was to determine whether a statistically and clinically significant difference in HbA(1c) could be achieved between a standard therapy and an intensively treated group of patients with type II diabetes. A second major goal was to assess the feasibility of collecting reliable high-quality endpoint data, including microvascular and macrovascular events. Retinopathy was defined as a key microvascular endpoint. RESEARCH DESIGN AND METHODS - This was a randomized prospective trial of 153 men between the ages of 40 and 69 years, with type II diabetes for 15 years or less. Of the patients, 78 were assigned to the standard therapy arm and 75 to the intensive therapy arm. The goal of standard therapy was good general medical care and well-being and avoiding excessive hyperglycemia, glycosuria, ketonuria, or hypoglycemia. This was generally accomplished with one shot of insulin per day. The goal of intensive therapy was to obtain an HbA(1c) within two standard deviations of the mean of nondiabetic subjects (4.0-6.1%). This was obtained by a four- step management technique, with patients moving to the next step only if operational goals were not met. The steps were as follows: step 1: evening intermediate or long-acting insulin only; step 2: evening insulin with daytime glipizide; step 3: insulin, twice a day, no glipizide; and step 4: more than two injections of insulin, no glipizide. Retinopathy was assessed at baseline, 12, and 24 months by seven-field stereo fundus photography done at each of the five participating VA medical centers and read at the Central Reading Center at the Department of Ophthalmology, University of Wisconsin Medical School, Madison. Visual acuity was determined by ophthalmologists at each of the participating hospitals. RESULTS - After the 6th month of the 24- month study, an average HbA(1c) of ~7.1% in the intensively treated group was sustained for the full study and was significantly lower than that seen in the standard group (9.2%, P < 0.001). Compliance in obtaining fundus photographs was excellent. Near normalization of glycemia did not cause transient worsening of retinal morphology nor did it prevent the onset or delay the progression of retinopathy. There was no effect on visual acuity. CONCLUSIONS - 1) A glycemic control intervention study in people with type II diabetes is feasible and safe; 2) intensive control did not cause transient deterioration of retinopathy; and 3) although no improvement was seen in retinopathy, the follow-up was 24 months, an interval shorter than the 3 years or more of intensive therapy before improvement is seen in type I diabetic studies. This does not rule out the possibility that longer periods of intensive therapy would have improved retinopathy. A full-scale intervention trial in type II diabetes is needed to resolve this issue.