In order to quantitatively evaluate atherosclerosis in borderline diabetes (BLDM), ultrasound high resolution B-mode imaging of the carotid artery was conducted to non-invasively determine the average thickness of the intimal-medial complex (avgIMC) in 92 BLDM subjects. The avgIMCs in BLDM was comparable to the valves in age-matched diabetics, but significantly higher than in 87 normal volunteers (1.17±0.20mm vs 0.73±0.09mm) 40's). Euglycemic clamping showed a significantly decrease in the glucose infusion rate of BLDM subjects than of normal volunteers. Hyperglycemic clamping a decrease in the first insulin secretory response in this group but not in second phase insulin secretion, and avgIMC was inversely (r=-0.445, p<0.05) correlated with decreased insulin sensitivity. These data indicate that BLDM subjects have advanced atherosclerosis in their carotid arteries, and that insulin resistance and the resulting hyperglycemia and heperinsulinemia may accelerate their atherosclerosis.