This study attempts to evaluate whether the putative excess risk of cardiovascular disease in individuals with impaired glucose tolerance (IGT) can be explained by the clustering of other major cardiovascular risk factors after controlling for obesity. The study population was 1376 male and female employees of a Naples telephone company who had participated in a health survey in which an oral glucose tolerance test (OGTT) was given. After excluding treated hypertensives, we recruited all 65 individuals with IGT and 125 euglycemic controls matched for gender, age, and weight. Systolic and diastolic blood pressure was significantly higher in individuals with IGT (134 +/- 16 vs 127 +/- 15 mm Hg, p less than 0.001; 87 +/- 10 vs 84 +/- 8 mm Hg, p less than 0.05 (M +/- SD). Blood lipids were similar in the two groups (total cholesterol was 214 +/- 34 vs 218 +/- 40 mg/dl; HDL cholesterol was 39 +/- 9 vs 40 +/- 10 mg/dl; total triglyceride was 145 +/- 58 vs 135 +/- 63 mg/dl). Serum insulin values (fasting or at 1 or 2 hours after 75 g of oral glucose) were also similar. The number of persons currently smoking was significantly lower among individuals with IGT (30% vs 47%, p less than 0.025) but the percentage of exsmokers was identical in the two groups. We conclude that, among the possible cardiovascular risk factors investigated, blood pressure is the only one significantly associated with IGT independent of matched variables and antihypertensive treatment.