BMI-Mortality Paradox and Fitness in African American and Caucasian Men With Type 2 Diabetes

OBJECTIVE-To assess the association between BM I, fitness, and mortality in African American and Caucasian men with type 2 diabetes and to explore racial differences in this association. RESEARCH DESIGN AND METHODS-We used prospective observational data from Veterans Affairs Medical Centers in Washington, DC, and Palo Alto, California. Our cohort (N = 4,156; mean age 60 +/- 10.3 years) consisted of 2,013 African Americans (mean age, 59.5 +/- 9.9 years), 2,000 Caucasians (mean age, 60.8 +/- 10.5 years), and 143 of unknown race/ethnicity. BMI, cardiac risk factors, medications, and peak exercise capacity in metabolic equivalents (METs) were assessed during 1986 and 2010. All-cause mortality was assessed across BMI and fitness categories. RESULTS-There were 1,074 deaths during a median follow-up period of 7.5 years. A paradoxic BMI-mortality association was observed, with significantly higher risk among those with a BMI between 18.5 and 24.9 kg/m(2) (hazard ratio [HR] 1.70 [95% CI 1.36-2.1]) compared with the obese category (BMI >= 35 kg/m(2). This association was accentuated in African Americans (HR 1.95 [95% CI 1.44-2.63]) versus Caucasians (HR 1.53 [1.0-2.1]). The fitness mortality risk association for the entire cohort and within BMI categories was inverse, independent, and graded. Mortality risks were 12% lower for each 1-MET increase in exercise capacity, and similar to 35-55% lower for those with an exercise capacity >5 METs compared with the least fit (<= 5 METs). CONCLUSIONS-A paradoxic BMI-mortality risk association was observed in African American and Caucasian patients with diabetes. The exercise capacity-mortality risk association was inverse, independent, and graded in all BM I categories but was more potent in those with a BMI >= 25 kg/m(2).