In the longitudinal Schwabing study, unselected insulin-treated diabetic patients were followed for major vascular complication (MVC) (stroke, myocardial infarction, gangrene) and asymptomatic, early detectable peripheral vascular disease (PVD). In the group of insulin-treated NIDDM multiple logistic regression analysis revealed the number of daily injected insulin units as a significant predictor for MVC and PVD (t = 1.98; p less than 0.04; x +/- S.D.: PVD yes 57.6 +/- 21.4 U/d; PVD no 44.3 +/- 17.7; age-adjusted univariate p less than 0.001). Daily insulin dose correlated highly significantly with serum triglycerides (r = 0.40, p less than 0.001) as well as with blood glucose (r = 0.33, p less than 0.001). These data suggest that insulin resistance is characteristic for atherosclerotic disease in NIDDM and the hyperinsulinemia-hypertriglyceridemia-syndrome might be a powerful cardiovascular risk factor in diabetes mellitus.