Background: The U-shaped association between body mass index (BMI) and mortality has been extensively reported in patients with type 2 diabetes. It has been shown that overweight patients had a lower mortality risk compared to normal-weight individuals, referred as “obesity paradox.” However, limited data reported the relation between on admission BMI and all-cause mortality in diabetic inpatients, and if obesity paradox exist in diabetic inpatients with microangiopathy.

Research Design and Methods: A total of 2885 patients had admitted due to a primary diagnosis of type 2 diabetic with poor glucose control were enrolled. BMI was measured when admission. Cox proportional hazards model hazard ratios for all-cause mortality were calculated after adjusting for confounders.

Results: During a mean follow-up period of 6.6 years, 1483 deaths occurred. A U-shaped association was observed between admission BMI and all-cause mortality, with BMI between 24 and 27 kg/m2 showing the lowest mortality risk across all BMI category. (BMI category including <18, 18-21.9, 22-23.9, 24-26.9, 27-29.9, ≥30 kg/m2, HR of 1, 0.68 [95% CI: 0.55 to 0.84], 0.54[95% CI: 0.43 to 0.67], 0.50[95% CI: 0.41 to 0.62], 0.52[95% CI: 0.41 to 0.65], 0.52[95% CI: 0.40 to 0.67, respectively]. However, among inpatients with macroalbuminuria, the protective effect of overweight was attenuated (P=0.52) and U-shaped association was not observed. The result was similar in patients with diabetes retinopathy (P=0.053).

Conclusions: A U-shaped association existed between admission BMI and all-cause mortality in diabetic inpatients. However, the obesity paradox was not observed in type 2 diabetic inpatients with existing diabetic microangiopathy.


L.Y. Hsuan: None. I. Lee: None.

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