RESEARCH DESIGN AND

Elevated heart rate has been predictive ofcardiovascular disease and total or car-diovascular mortality (1–3). Heart rate has been proposed as a global index of the autonomic nervous system influence on the heart (4), and elevated heart rate may reflect a shift in autonomic balance toward enhanced sympathetic and suppressed vagal tone. Hyperinsulinism has been shown to trigger sympathetic activity experimentally (5–7); however, the clinical and epidemio-logic data on the association of heart rate with hyperinsulinism and insulin resistance are conflicting (8–12). Herein, we sought to investigate the relation of heart rate to fasting insulin, its precursors (intact and split proinsulin), as well as insulin sensitivity (SI) and the acute insulin response (AIR). This was measured by a frequently sampled intravenous glu-cose tolerance test (FSIGTT) and minimal model analysis, in a large tri-ethnic nondi-abetic population (n = 1,000). The focus of this study is on nondiabetic individuals to simplify the analysis and because previous studies have shown 1) a strong association of postload glucose levels with heart rate (9) and 2) a limited range of SI in patients with type 2 diabetes (13)