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

Diabetes Care, Jun 2007

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.

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

PAUL A. MCAULEY PHD JONATHAN N. MYERS PHD JOSHUA P. ABELLA SWEE Y. TAN VICTOR F. FROELICHER C a r d i o v a s c u l a r a n d 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/m 2), 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 (18.524.9, 25.0 -29.9, and 30 kg/m 2) 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. - I for military service differ from the genndividuals volunteering and qualifying eral population in several respects; most notably, they had to have met fitness and weight criteria at the time of their enlistment and must have maintained these levels for the duration of their service. For e x a m p l e , t h e m a x i m u m a l l o w a b l e weights for the various branches of service translate into a BMI of 25.9 29.9 kg/m2 (1). Therefore, obesity, when present in a veteran patient population, must have developed after discharge, thus providing an opportunity to evaluate the risk of mortality associated with low fitness and obesity developing in later life. While obesity is a well-recognized risk factor for the development of type 2 diabetes (2), it is uncertain whether obesity is an independent mortality predictor in people already having the disease. Moreover, the association of fitness with mortality in patients with diabetes remains largely unexplored. Recent reports have suggested that mortality risk in men with type 2 diabetes is independent of BMI after adjustment for fitness (3,4). Because this observation runs contrary to current clinical beliefs, we decided to explore this further using a subpopulation of male veterans with documented type 2 diabetes from our exercise testing database. The primary aims of this study of male veterans with type 2 diabetes were to examine 1) the independent risks of mortality associated with low fitness and adult-onset obesity and 2) the associations among fitness, BMI, and mortality. RESEARCH DESIGN AND METHODS The Veterans Exercise Testing Study (VETS) is a prospective epidemiologic investigation of 7,000 veteran patients referred to two universityaffiliated Veterans Affairs medical centers (Long Beach VA, from 1987 to 1991; Palo Alto VA, from 1992 to 2006). From this database, a total of 869 men were recognized as having type 2 diabetes. (Cases of type 2 diabetes could only be documented from 1995 onwards; hence, all participants in the current study were evaluated at the Palo Alto VA.) Of these, 36 subjects were excluded because of missing data on height, weight, or exercise capacity. In addition, two patients were excluded because they were underweight (BMI 18.5 kg/m2). Therefore, participants for the present analysis were 831 men with type 2 diabetes who completed a baseline medical examination and maximal exercise test at least once at the Palo Alto VA Health Care System between 1995 and 2006. Type 2 diabetes was defined as a physician-diagnosed history of type 2 diabetes, treatment with an oral hypoglycemic agent, or a fasting plasma glucose level 7.0 mmol/l (126 mg/dl) at baseline (5). Only two patients were identified as receiving insulin treatment at baseline. The study population consisted of 62% non-Hispanic whites, 15% Hispanics, and 14% African Americans who ranged in age from 23 to 88 years (average 61.3 9.3). All subjects gave informed consent for participation in the study. Additional information on study methods and subject characteristics of this cohort have been published elsewhere (6,7). Mortality surveillance Study participants were followed from their baseline examination until their death or until 30 J (...truncated)


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Paul A. McAuley, Jonathan N. Myers, Joshua P. Abella, Swee Y. Tan, Victor F. Froelicher. Exercise Capacity and Body Mass as Predictors of Mortality Among Male Veterans With Type 2 Diabetes, Diabetes Care, 2007, pp. 1539-1543, 30/6, DOI: 10.2337/dc06-2397