Body mass index and risk of all-cause and cardiovascular mortality in hospitalized elderly patients with diabetes mellitus

Aims: Obesity is linked to increased morbidity and mortality risk in both the general population and in patients with diabetes mellitus; however, recent reports suggest that, in hospitalized elderly individuals, the association between body mass index (BMI) and mortality may be inverse. The present study sought to investigate the association between BMI and survival in hospitalized elderly individuals with diabetes mellitus. Methods: The medical records of 470 patients (226 males, mean age of 81.5 ± 7.0 years) admitted to an acute geriatric ward between 1999 and 2000 were reviewed. Of the 140 patients with diabetes mellitus, 122 had more than 6 months of follow-up and were included in this analysis. Patients were followed up until 31 August 2004. Mortality data were extracted from death certificates. Results: During a mean follow-up of 3.7 ± 1.6 years, 69 (56.6%) subjects died, 31 (25.4%) from cardiovascular causes. Those who died from any cause had lower baseline BMI than those who survived (24.0 ± 4.0 vs. 27.1 ± 4.3 kg/m ²; P < 0.0001). Similarly, those who died of cardiovascular causes had lower baseline BMI than those who did not (23.7 ± 3.6 vs. 25.9 ± 4.5, P = 0.01). BMI was inversely associated with all-cause [relative risk (RR) 0.89, 95% confidence interval (CI) 0.83-0.96, P = 0.002] and cardiovascular death (RR 0.83, 95% CI 0.74-0.93, P = 0.002) even after controlling for age, sex, smoking, dyslipidaemia and reason for hospital admission. Conclusions: In very elderly subjects with diabetes mellitus, increased BMI was associated with reduced mortality risk.