Impact of obesity on mortality in patients with diabetes: Meta‐analysis of 20 studies including 250,016 patients

Aims/Introduction The impact of body mass index on mortality among patients with diabetes remains controversial. Therefore, we carried out a meta‐analysis of pertinent studies. Materials and Methods We searched OVID / MEDLINE , EMBASE and Cochrane databases for all reported studies, which investigated the relationship between body mass index and mortality in patients with diabetes. Summary estimates of hazard ratios ( HR s) were obtained with a random effects model. Univariate meta‐regressions were carried out. Results A total of 20 studies including 250,016 patients with diabetes were identified. The results of the present study showed a significantly reduced risk of all‐cause mortality in overweight patients ( HR 0.82, 95% CI : 0.74–0.91, P < 0.0001, and I 2 = 91.6%) as compared with normal weight patients. The survival benefits of obesity were only observed in the elderly patients ( HR 0.69, 95% CI : 0.63–0.75, P < 0.0001, and I 2 = 50.4%), but not in the younger patients ( HR 1.01, 95% CI : 0.84–1.20, P = 0.96, I 2 = 80.1%). Furthermore, the beneficial prognostic impacts on overweight (coefficient = 0.030, P = 0.041) and obesity (coefficient = 0.032, P = 0.010) were attenuated with clinical follow‐up duration. Conclusions The present meta‐analysis showed a significantly lower risk of all‐cause mortality in overweight patients with diabetes compared with normal weight patients. However, the survival benefits of obesity were only observed among the elderly patients.