Myocardial infarction before the age of 40 years is associated with insulin resistance

Insulin resistance is associated with atherosclerosis, and hyperinsulinemia is predictive of coronary heart disease. However, a quantitative estimatio n of in vivo insulin sensitivity in juvenile myocardial infarction is still lacking and the mechanism of hyperinsulinemia is unknown. We estimated ins ulin sensitivity, p-cel secretion, and hepatic insulin extraction using the minimal model analysis of a frequently sampled intravenous glucose toleran ce test (FSIGT) in 25 normal-weight subjects without glucose intolerance an d hypertension who had an acute myocardial infarction before the age of 40 years, and 10 control subjects comparable for age, sex, body mass index, an d blood pressure. All patients underwent a coronary angiography. Insulin se nsitivity was significantly lower in patients than in control subjects (mea n +/- SEM, 4.6 +/- 0.6 v 8.5 +/- 1.2 10(-4) min(-1)/(muU/mL), P = .002). Th e basal C-peptide secretion rate (P = .02), total C-peptide secretion (P = .005), area under the curve (AUC) of insulin (P = .04) and C-peptide (P = . 01), and hepatic insulin extraction (P = .04) were higher in patients versu s central subjects. in conclusion, insulin resistance is evident in subject s with early myocardial infarction accurately selected to avoid the influen ce of other factors known to reduce insulin sensitivity, and hyperinsulinem ia is due to an increase in beta -cell secretion rather than a decrease in hepatic insulin extraction. Copyright (C) 2001 by W.B. Saunders Company.