Body-Mass Index and All-Cause Mortality in US Adults With and Without Diabetes

Abstract

BACKGROUND: 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. OBJECTIVE: To determine if diabetes influences the BMI-mortality relationship. DESIGN: 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. PARTICIPANTS: Excluding those with heart disease or cancer, our final analytic sample included 74,710 (34,805 never smoker) adults. MAIN MEASURES: BMI was calculated from selfreported height and weight. Diabetes status was based on self-reported diagnosis from a health professional. We used direct age standardization to calculate allcause mortality rates and adjusted Cox models for allcause mortality hazard ratios by BMI quintile; this was done separately for adults with diabetes and without diabetes. KEY RESULTS: 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 BMImortality 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. CONCLUSIONS: 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.

Nonlinear association of BMI with all-cause and cardiovascular mortality in type 2 diabetes mellitus: a systematic review and meta-analysis of 414,587 participants in prospective studies

“…Grey shading indicates 95% CI smokers in both Black and White participants [41]. In comparison Jackson and colleagues did not find a variation in the association between BMI and mortality by smoking status [30]. Our findings showed a nonlinear relationship between BMI and all-cause mortality in people with diabetes, with the lowest risk around 33 kg/m 2 .…”

“…1). Following detailed assessments, and after the inclusion of three articles identified from manual searches, 21 articles were included in the quantitative analysis (21 studies and 24 unique cohorts; Table 1) [7,8,11,15,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Study characteristics and the NOS scores are provided in ESM Tables 1-3.…”

Is Mortality Risk Reduced in Overweight or Obese Diabetics?

“…The study by Jackson et al 7 indicates that mortality increases with increasing BMI in adults without diabetes, but decreases with increasing BMI among their counterparts with diabetes. Their finding in diabetic patients might be of particular interest to developers of practice guidelines for the American Diabetes Association, and might also support the recent finding from the Look AHEAD (Action for Health in Diabetes) study.…”

“…Most previous studies did not exclude patients with a history of CVD and cancer when they assessed the association between BMI and the risk of mortality among individuals with type 2 diabetes. [4][5][6] The analysis by Jackson et al 7 excluded individuals who reported a prior history of cancer and/or coronary heart disease, which can minimize the influence of reverse causation.…”

“…The most satisfactory way to deal with the presence of smokers in a study database is to restrict the analysis to subjects who have never smoked, as did Jackson et al and other investigators. 3,5,7 However, many previous studies had small samples, and thus lacked adequate statistical power when the analysis was limited to those who have never smoked. 4,6 The third methodological concern in some analyses between body weight and mortality is that the physiologic effects of excess fatness, such as hypertension, diabetes, and dyslipidemia, were controlled statistically, thus artificially removing some of the effects of being overweight.…”