Prognostic effect of exercise capacity on mortality in older adults with diabetes mellitus

Abstract

Objectives: To investigate the prognostic effect of exercise capacity in older individuals with diabetes mellitus.

Design: Retrospective data review in a clinic-based cohort.

Setting: Veterans Affairs Medical Centers in Washington, District of Columbia, and Palo Alto, California.

Participants: Two thousand eight hundred sixty-seven men aged 50 to 87 with type 2 diabetes mellitus.

Measurements: Exercise tolerance testing with fitness categories based on peak metabolic equivalents of task (METs) achieved adjusted for age. All-cause mortality in age groups 50 to 65 (Group 1; n=1,658) and older than 65 (Group 2; n=1,209) was analyzed using adjusted Cox proportional hazards models.

Results: After a mean ± standard deviation follow-up period of 7.8 ± 5.1 years, there were 324 deaths in Group 1 (20%) and 464 in Group 2 (38%). For each 1-MET increase in exercise capacity, mortality was 18% lower for the entire cohort (hazard ratio (HR)=0.82, 95% confidence interval (CI)=0.79-0.86), 23% lower for Group 1 (HR=0.77, 95% CI=0.73-0.82), and 16% lower for Group 2 (HR=0.84, 95% CI=0.8-0.89). When fitness categories were considered, the mortality risk was 30% to 80% lower for those who achieved more than 4 METs in both age groups.

Conclusion: Augmented exercise capacity is associated with lower risk of mortality in people with type 2 diabetes mellitus aged 50 to 65 as well as in those older than 65. Thus, physical fitness, as represented by exercise capacity, lowers mortality risk in people with diabetes mellitus irrespective of age. These findings suggest that healthcare providers should be cognizant of the level of exercise capacity in individual patients and encourage a physically active lifestyle regardless of age.