Objective: Individuals with diabetes have an excess mortality compared with people without diabetes. This study used a national cohort of older Spanish adults to identify possible factors explaining the relation between diabetes and excess mortality.
Research design and methods: A cohort of 4,008 people ≥60 years of age was selected in 2000-2001 and followed prospectively until 2008. At baseline, data were collected on diabetes and major risk factors for mortality: social network, diet, physical activity and other lifestyle factors, obesity, hypertension, dyslipidemia, and previous cardiovascular disease and cancer. Analyses were conducted with Cox regression with progressive adjustment for mortality risk factors.
Results: In the study cohort, 667 people had diabetes. A total of 972 deaths occurred during follow-up. The hazard ratio (HR) and 95% CI for mortality in diabetic versus nondiabetic subjects, adjusted for age, marital status, education level, social class, medical consultation, and treatment with statins, angiotensin II antagonists, or aspirin, was 1.40 (1.11-1.76) in men and 1.70 (1.37-2.10) in women. Adjustment for additional risk factors produced little change in the HR. After adjustment for all risk factors, including cardiovascular disease and cancer, the mortality HR in diabetic versus nondiabetic individuals was 1.43 (1.12-1.82) in men and 1.67 (1.34-2.08) in women. The inclusion of lifestyles and diseases occurring during follow-up also produced little change in the relation between diabetes and mortality.
Conclusions: The excess risk of mortality in diabetic versus nondiabetic individuals cannot be explained by mortality risk factors or by the presence of cardiovascular disease or cancer.