Jackson Chandra L, Yeh Hsin-Chieh, Szklo Moyses, Hu Frank B, Wang Nae-Yuh, Dray-Spira Rosemary, Brancati Frederick L
Department of Nutrition, Harvard School of Public Health, Boston, MA, USA,
J Gen Intern Med. 2014 Jan;29(1):25-33. doi: 10.1007/s11606-013-2553-7. Epub 2013 Aug 9.
Previous studies found normal weight compared to overweight/obese adults with type 2 diabetes had a higher mortality risk, and body-mass index (BMI)-mortality studies do not typically account for baseline diabetes status.
To determine if diabetes influences the BMI-mortality relationship.
Using a prospective study design, we analyzed data from a nationally representative sample of US adults participating in the National Health Interview Survey from 1997 to 2002, and followed for mortality through 2006.
Excluding those with heart disease or cancer, our final analytic sample included 74,710 (34,805 never smoker) adults.
BMI was calculated from self-reported height and weight. Diabetes status was based on self-reported diagnosis from a health professional. We used direct age standardization to calculate all-cause mortality rates and adjusted Cox models for all-cause mortality hazard ratios by BMI quintile; this was done separately for adults with diabetes and without diabetes.
Among never smokers, mean age was 50.1 years and 43 % were men. Mean BMI was 27.4 kg/m(2), 26 % were obese, and 2,035 (5 %) reported diagnosed diabetes. After 9 years, there were 4,355 deaths (754 of 4,740 with diabetes; 3,601 of 69,970 without) among 74,710 participants, and 1,238 (247 of 2,035 with diabetes; 991 of 32,770 without) among 34,805 never smokers. We observed a qualitative interaction with diabetes on the BMI-mortality relationship (p = 0.002). Death rates were substantially higher among participants with diabetes compared to those without diabetes across all BMI quintiles. However, death rates in participants with diabetes fell with increasing BMI quintile, while rates followed a J-shaped curve among those without diabetes. In adjusted Cox models, BMI was positively associated with mortality in adults without diabetes, but inversely associated with mortality among participants with diabetes.
Mortality increased with increasing BMI in adults without diabetes, but decreased with increasing BMI among their counterparts with diabetes. Future studies need to be better designed to answer the question of whether normal weight adults with diabetes have a higher risk of mortality, by minimizing the possibility of reverse causation. Future studies should also account for prevalent diabetes in all investigations of the BMI-mortality relationship.
先前的研究发现，与超重/肥胖的2型糖尿病成年人相比，体重正常者的死亡风险更高，而且体重指数（BMI）与死亡率的研究通常未考虑基线糖尿病状态。
确定糖尿病是否会影响BMI与死亡率之间的关系。
采用前瞻性研究设计，我们分析了1997年至2002年参加美国国家健康访谈调查的具有全国代表性的美国成年人样本数据，并追踪至2006年的死亡率。
排除患有心脏病或癌症的人后，我们最终的分析样本包括74710名（34805名从不吸烟者）成年人。
根据自我报告的身高和体重计算BMI。糖尿病状态基于健康专业人员的自我报告诊断。我们使用直接年龄标准化来计算全因死亡率，并通过BMI五分位数对全因死亡率风险比进行调整的Cox模型分析；对患有糖尿病和未患糖尿病的成年人分别进行了此项分析。
在从不吸烟者中，平均年龄为50.1岁，男性占43%。平均BMI为27.4kg/m²，26%为肥胖者，2035人（5%）报告被诊断患有糖尿病。9年后，74710名参与者中有4355人死亡（4740名糖尿病患者中有754人死亡；69970名非糖尿病患者中有3601人死亡），34805名从不吸烟者中有1238人死亡（2035名糖尿病患者中有247人死亡；32770名非糖尿病患者中有991人死亡）。我们观察到糖尿病在BMI与死亡率关系上存在定性交互作用（p = 0.002）。在所有BMI五分位数中，糖尿病患者的死亡率显著高于非糖尿病患者。然而，糖尿病患者的死亡率随着BMI五分位数的增加而下降，而非糖尿病患者的死亡率呈J形曲线。在调整的Cox模型中，BMI与非糖尿病成年人的死亡率呈正相关，但与糖尿病患者的死亡率呈负相关。
在无糖尿病的成年人中，死亡率随BMI升高而增加，但在患有糖尿病的成年人中，死亡率随BMI升高而降低。未来的研究需要进行更好的设计，通过尽量减少反向因果关系的可能性，来回答糖尿病体重正常的成年人是否有更高死亡风险这一问题。未来的研究在所有BMI与死亡率关系的调查中也应考虑普遍存在的糖尿病情况。
