THE ROLE OF INSULIN IN CORONARY ATHEROSCLEROSIS

In 197 patients with coronary artery disease (CAD) who underwent coron ary angiography, 75 g oral glucose tolerance test (OGTT) was performed , measuring plasma glucose(PG) and plasma insulin (IRI) at 4 time poin ts (0, 30, 60 and 120 min). Subjects were separated into two groups by their insulinogenic index (I.I. = Delta IRI/Delta PG from 0 up to 30 min), 99 cases with good insulin response (I.I. greater than or equal to 0.4) and 98 cases with poor insulin response (I.I. < 0.4). Only two subjects were diabetic in good insulin response, while 37 were diabet ic in poor insulin response. The severity of coronary atherosclerosis was expressed as a coronary index (CI), calculated according to Balcon 's method. Fasting PG and the sum of PG were significantly higher in t he latter group, while the sum of IRI was significantly lower. CI was not significantly different, however. In the group with good insulin r esponse, the severity of CAD was significantly correlated to fasting I RI (n = 99, r = -0.387, P < 0.02), but, there was no such relationship in the other group. We conclude that hyperinsulinemia might be a risk factor for ischemic heart disease, but in diabetics it is difficult t o link the relationship between fasting IRI and CI.