Background: We tested the hypothesis that selected exercise heart rate responses, specifically those providing indices of autonomic dysfunction, may be associated with incident type 2 diabetes in 2231 apparently healthy men with normal baseline fasting glucose levels.
Methods: Heart rate reserve was calculated as the difference between the maximal attained heart rate and the supine resting heart rate, whereas heart rate recovery was defined as the maximal heart rate minus the heart rate measured at 2 minutes of recovery after peak or symptom-limited cardiopulmonary exercise testing. Type 2 diabetes was defined as glycated hemoglobin >6.5% or fasting plasma glucose >126 mg/dL at the follow-up examination.
Results: During a median follow-up interval of 5 years, 90 of the 2231 men (4.0%) developed type 2 diabetes. The relative risks of incident type 2 diabetes in men within the lowest quartiles of heart rate reserve and heart rate recovery versus men comprising the highest quartiles of heart rate reserve and heart rate recovery were 2.71 (95% confidence interval, 1.20-6.11) and 2.81 (95% confidence interval, 1.36-5.78) after adjusting for potential confounding variables. Each unit increment (1 beat/min) in heart rate reserve and heart rate recovery was associated with a 2% to 3% decreased incidence of type 2 diabetes.
Conclusions: Exercise heart rate reserve and recovery predicted incidence of type 2 diabetes in healthy men, suggesting that autonomic dysfunction may be associated with an increased likelihood for the development of this cardiometabolic risk factor.
Keywords: Exercise; Heart rate recovery; Heart rate reserve; Type 2 diabetes.
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