Chronotropic response to exercise and risk of type 2 diabetes in men

Abstract

Impaired heart rate response to exercise, an estimate of decreased autonomic nervous system function, has been associated with cardiovascular mortality and sudden cardiac death. However, little is known about the chronotropic response to exercise may contribute to the development of type 2 diabetes. We tested the hypothesis that poor heart rate response to exercise stress testing is associated with the incidence of type 2 diabetes in healthy men. Subjects were 3123 men (mean age 47±6 yrs) who participated in two health examinations during 1998-2009. All subjects were free of cardiovascular diseases and type 2 diabetes at baseline. Type 2 diabetes was defined as >6.5% of HbA1c or >126mg/dl of fasting glucose at second examination. Chronotropic response was defined as the heart rate reserve, calculated as the difference between maximal heart rate during the exercise test and resting heart rate. During an average follow-up of 5 years, 137 (4.4%) men developed type 2 diabetes. The incidence of type 2 diabetes was inversely associated with heart rate reserve across quartiles (Q1 (<91bpm) 6.0%, Q2 (91∼99bpm) 4.8%, Q3 (100∼107bpm) 4.3%, and Q4 (>107bpm) 2.4%; p <0.001 for trend). The relative risk (RR) of incident type 2 diabetes in men with low heart rate reserve versus men with high heart rate reserve was 2.96 (95% CI, 1.60-5.46, p=0.006) after adjustment for age, BMI, SBP, TC, HDL-C, TG, glucose, WBC, albumin, uric acid, resting HR, VO2peak, smoking and alcohol intake. Each increment in heart rate reserve (1 bpm) was associated with a 2% (RR 0.98, 95% CI 0.97-0.99, p=0.017) decrease in the incidence of type 2 diabetes after adjustment for risk factors. Our study demonstrates that poor heart rate response to exercise test is associated with the incidence type 2 diabetes independent of risk factors in healthy men. It suggests that attenuated autonomic function may be associated with the risk of type 2 diabetes in healthy men.