Heart rate in relation to insulin sensitivity and insulin secretion in nondiabetic subjects.

OBJECTIVE Elevated heart rate has been predictive of cardiovascular disease and has been proposed as a global index of the autonomic nervous system influence on the heart. Hyperinsulinism has been shown to trigger sympathetic activity experimentally; however, the clinical and epidemiological data on the association of heart rate with hyperinsulinism and insulin resistance are conflicting. RESEARCH DESIGN AND METHODS Insulin sensitivity (S(I)) and the acute insulin response (AIR) to glucose were assessed by a frequently sampled intravenous glucose tolerance test and related to resting heart rate in the tri-ethnic nondiabetic population (n = 1,000) of the Insulin Resistance Atherosclerosis Study. RESULTS Heart rate was related to fasting insulin (r = 0.20), intact proinsulin (r = 0.15), split proinsulin (r = 0.17), and AIR (r = 0.18), and an inverse relation was found between heart rate and S(I) (r = -0.19) (all P values <0.0001, adjusted for age, sex, ethnicity, glucose tolerance status, and smoking). In a multiple linear regression analysis (adjusting for age, sex, ethnicity, clinical center, glucose tolerance status, and smoking), heart rate was significantly and independently associated with AIR, proinsulin, and S(I). CONCLUSIONS Proinsulin, acute insulin secretion, and S(I) are associated with heart rate in nondiabetic subjects.