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 2 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 between 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 (HR, 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 (HR, 1.70 [95% CI 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.