Obesity is a dominant risk factor for type 2 diabetes, but its relation with mortality among those with pre-existing chronic illnesses like diabetes, regardless of type, is controversial. Using the Southern Community Cohort Study, we conducted a mortality follow-up (2002-2014) of a cohort of mostly low income black and white participants aged 40-79 with young-onset (diagnosed < age 30, n=1,378) and older onset (diagnosed ≥ 30, n= 15,707) diabetes. Cox analysis with age as the time scale was used to compute HRs (95% CIs) for all-cause mortality by BMI at cohort entry. Mean baseline age and diabetes duration were 50.1 and 29.4 years and 55.3 and 7.7 years among those with young and older onset diabetes, respectively. During an average of 9.4 years of follow-up, 24% of the patients died. Regardless of age at diabetes onset, excess mortality was observed in the underweight, but the overweight or obese had lower death rates than those of normal weight. In analyses controlling for diabetes duration, sex, race, use of insulin, hyperlipidemia and cholesterol meds, hypertension, a history of stroke/tia, coronary heart disease, education, income, and health insurance coverage, compared to a normal BMI of 18-<25 kg/m2,, HRs (95% CIs) were 4.13 (1.48-11.54), 0.56 (0.41-0.77), 0.71 (0.51-0.97), 0.46 (0.31-0.67), 0.59 (0.40-0.86) for BMI categories <18.5, 25-<30, 30-<35, 35-<40, 40+ kg/m2 among those with young-onset diabetes, with similar estimates observed for both blacks and whites. For older onset diabetes, corresponding HRs (95% CIs) were 1.96 (1.42-2.71), 0.70 (0.62-0.78), 0.65 (0.58-0.73), 0.72 (0.64-0.81), 0.99 (0.88-1.12); however, some differences by race (p interaction= 0.01) emerged, with increased risk of mortality for those with a BMI ≥ 40 among whites (HR=1.36, 1.07-1.71) but not blacks (HR=0.89, 0.76-1.03). Among this indigent population of blacks and whites with diabetes, overweight and obesity appear to be protective against mortality, particularly among those with young-onset diabetes and among blacks with older-onset diabetes.
B. Conway: None. W.J. Blot: None.
National Cancer Institute