OBJECTIVE Type 2 diabetes is strongly associated with obesity, but the mortality risk related to elevated body weight in people with type 2 diabetes compared with people without diabetes has not been established.

RESEARCH DESIGN AND METHODS We prospectively assessed short- and long-term mortality in people with type 2 diabetes with a recorded diabetes duration ≤5 years identified from the Swedish National Diabetes Register (NDR) between 1998 and 2012 and five age- and sex-matched control subjects per study participant from the general population.

RESULTS Over a median follow-up of 5.5 years, there were 17,546 deaths among 149,345 patients with type 2 diabetes (mean age 59.6 years [40% women]) and 68,429 deaths among 743,907 matched control subjects. Short-term all-cause mortality risk (≤5 years) displayed a U-shaped relationship with BMI, with hazard ratios (HRs) ranging from 0.81 (95% CI 0.75–0.88) among patients with diabetes and BMI 30 to <35 kg/m² to 1.37 (95% CI 1.11–1.71) with BMI ≥40 kg/m² compared with control subjects after multiple adjustments. Long-term, all weight categories showed increased mortality, with a nadir at BMI 25 to <30 kg/m² and a stepwise increase up to HR 2.00 (95% CI 1.58–2.54) among patients with BMI ≥40 kg/m², that was more pronounced in patients <65 years old.

CONCLUSIONS Our findings suggest that the apparent paradoxical findings in other studies in this area may have been affected by reverse causality. Long-term, overweight (BMI 25 to <30 kg/m²) patients with type 2 diabetes had low excess mortality risk compared with control subjects, whereas risk in those with BMI ≥40 kg/m² was substantially increased.

目的2型糖尿病与肥胖密切相关，但与2型糖尿病患者相比，2型糖尿病患者的体重升高与死亡风险有关。

研究设计和方法我们前瞻性地评估了1998年至2012年间从瑞典国家糖尿病登记（NDR）确定的5个年龄和性别相匹配的2型糖尿病患者的短期和长期死亡率，该患者的记录的糖尿病持续时间≤5年普通人群中每个研究参与者的控制对象。

结果在5.5年的中位随访中，149,345名2型糖尿病患者（平均年龄59.6岁[40％女性]）中有17,546例死亡，而743,907名匹配的对照组中有68,429例死亡。短期全因死亡率风险（≤5年）与BMI呈U型关系，糖尿病和BMI 30至<35 kg的患者的危险比（HRs）为0.81（95％CI 0.75–0.88） /米²与BMI≥40到1.37（95％CI 1.11-1.71）公斤/米²与后多次调整对照组相比。长期，所有的重量类别显示出在BMI 25增加的死亡率，与最低点到<30千克/米²，并逐步增大到患者BMI之间HR 2.00（95％CI 1.58-2.54）≥40公斤/米²在65岁以下的患者中更为明显。

结论我们的发现表明，该领域其他研究中明显的悖论性发现可能已受到反向因果关系的影响。与对照组相比，长期，超重（BMI 25至<30 kg / m ²）患者的过高死亡风险低，而BMI≥40 kg / m ^2的患者的风险大大增加。