Association between obesity and risk for all-cause mortality in patients with type 2 diabetes

Abstract

Objective: To investigate the association between obesity and the risk for all-cause mortality in type 2 diabetes (T2DM) patients. Methods: The participants were from a rural community-based T2DM patient cohort in Zhejiang Province. The study used the data collected from baseline survey in 2016 and follow-up until December 31, 2021. A total of 10 310 participants were included, excluding those who were lost in follow-up or had incomplete data in follow-up. According to BMI and waist circumference, the study subjects were divided into 6 groups: low body weight, normal body weight, simple abdominal obesity, simple body obesity, complex overweight and complex obesity. Cox proportional hazards regression model was used to analyze hazard ratios (HRs) of all-cause mortality and their 95%CIs in T2DM patients with different obesity status. Results: The cumulative follow-up period was 57 049.47 person-years with an average follow-up of (5.53±0.89) person-years. During this period, 971 subjects died. The death density was 1 702.03/100 000 person-years. After adjusting for confounders, low-weight patients had a 104% increased risk for all-cause death compared with normal-weight patients (HR=2.04, 95%CI:1.42-2.92). The risk for all-cause death decreased by 34% (HR=0.66, 95%CI: 0.53-0.82), 22% (HR=0.78,95%CI: 0.66-0.92), 38% (HR=0.62, 95%CI: 0.49-0.78) in the patients with simple body obesity, complex overweight and complex obesity, respectively, there was no significant difference for all-cause death in the patients with simple abdominal obesity alone. In subgroup analysis, the risk of all-cause mortality increased in low-weight T2DM patients of different sexes and ages, the mortality risk in women with complex obesity was 50% lower than that in the women with normal body weight, but there was no significant difference in men in the comparison between complex obesity group and normal body weight group. The risk for all-cause mortality was significantly lower in ≥65 years old patients with simple body obesity, complex overweight and complex obesity than in patients with normal body weight (HR=0.61, 95%CI: 0.48-0.78; HR=0.76, 95%CI: 0.63-0.91; HR=0.56,95%CI: 0.42-0.73), there was no significant difference in the patients aged <65 years. There was no significant change in sensitivity analysis. Conclusions: There was an "obesity paradox" in the risk for all-cause mortality in T2DM patients. The risk of all-cause mortality in the low-weight patients was significantly higher than that in normal-weight patients, and the risk for death in the patients with simple body obesity or complex overweight and obesity were significantly lower.