A study was undertaken to demonstrate the relationship between known risk factors for coronary artery disease and hyperinsulinemia in both patients without diabetes and patients with non-insulin-dependent diabetes mellitus. Both groups of patients were categorized based on insulin levels in the fasting and 2-hour post glucose challenge state, in relation to the median insulin level for that group. Patients with an insulin level higher than the median value were compared with those with lower insulin levels. Differences in weight; levels of fasting glucose, insulin at 2 hours post glucose challenge, total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol; presence of hypertension; and history of smoking cigarettes-known risk factors for atherosclerosis-were analyzed. An elevated fasting insulin level was found to be strongly associated with a number of atherogenic risk factors in both sets of patients. Weight was the only factor with a consistently positive association with the insulin level in all subgroups. In both groups, the fasting insulin level was associated with more risk factors than the insulin level at 2 hours after administration of 75 g of oral glucose.