Postprandial (pp) hyperglycemia--frequently associated with an increase in cardiovascular risk factors--may be damaging for the endothelium. So far, little information exists how glucose, insulin and lipids may affect atherosclerosis in the pp state. Therefore, we evaluated the relationship of pp hyperglycemia, insulin secretion and coronary risk factors to intima-media thickness (IMT) in a non-diabetic risk population. In 403 subjects (147 males, 256 females), aged 40-70 years, in the majority relatives of index cases with type 2 diabetes--a 75 g oral glucose tolerance test was performed together with measurement of insulin fractions, various risk factors and IMT of the common carotid artery. We found a continuous rise of 2h pp insulin fractions along the quintiles of 2h pp plasma glucose. A significant increase of body mass index, waist to hip ratio, triglycerides and decrease of HDL-cholesterol was observed in the top quintile of 2h pp plasma glucose (8.24 > or = pp plasma glucose < 11.1 mmol/l). Albuminuria was significantly enhanced in the 5th quintile. In parallel, IMT was significantly increased in the 5th quintile versus the bottom quintile of 2 h and maximal glucose (range 11.7-15.3 mmol/l) postprandially. After age and sex adjustment pp glucose and C-peptide, total cholesterol, triglycerides and HDL-cholesterol but not fasting plasma glucose were significantly correlated to IMT. In multivariate analysis age, male sex, pp plasma glucose, total and HDL-cholesterol were found to be independent risk factors for increased IMT. In conclusion, our data in a non-diabetic European risk population show that the two top quintiles of pp plasma glucose are associated with a clustering of standard risk factors. Corresponding to this clustering of risk factors IMT was significantly increased in the top quintile of 2 h and maximal pp plasma glucose. These data show that pp hyperglycemia may exert a noxious impact on the arterial wall together with a cluster of anomalies typical for the metabolic syndrome.