Exercise Capacity and Body Mass as Predictors of Mortality Among Male Veterans With Type 2 Diabetes

Abstract

OBJECTIVE—To demonstrate the relation of exercise capacity and BMI to mortality in a population of male veterans with type 2 diabetes.

RESEARCH DESIGN AND METHODS—After excluding two underweight patients (BMI <18.5 kg/m²), the study population comprised 831 consecutive patients with type 2 diabetes (mean age 61 ± 9 years) referred for exercise testing for clinical reasons between 1995 and 2006. Exercise capacity was determined from a maximal exercise test and measured in metabolic equivalents (METs). Patients were classified both according to BMI category (18.5–24.9, 25.0–29.9, and ≥30 kg/m²) and by exercise capacity (<5.0 or ≥5.0 maximal METs). The association among exercise capacity, BMI, other clinical variables, and all-cause mortality was assessed by Cox proportional hazards. Study participants were followed for mortality up to 30 June 2006.

RESULTS—During a mean follow-up of 4.8 ± 3.0 years, 112 patients died, for an average annual mortality rate of 2.2%. Each 1-MET increase in exercise capacity conferred a 10% survival benefit (hazard ratio 0.90 [95% CI 0.82–0.98]; P = 0.01), but BMI was not significantly associated with mortality. After adjustment for age, ethnicity, examination year, BMI, presence of cardiovascular disease (CVD), and CVD risk factors, diabetic patients achieving <5 maximal METs were 70% more likely to die (1.70 [1.13–2.54]) than those achieving ≥5 maximal METs.

CONCLUSIONS—There was a strong inverse association between exercise capacity and mortality in this cohort of men with documented diabetes, and this relationship was independent of BMI.