No ‘obesity paradox’ for mortality found in diabetics
A new study found no evidence of a mortality benefit for diabetics in being obese or overweight and thus did not support the so-called “obesity paradox.”
A new study found no evidence of a mortality benefit for diabetics in being obese or overweight and thus did not support the so-called “obesity paradox.”
Researchers studied participants with diabetes from the Nurses' Health Study (8,970 participants) and the Health Professionals Follow-up Study (2,457 participants) who were free of cardiovascular disease and cancer at the time of their diabetes diagnosis. Body weight shortly before diagnosis and height were used to calculate body mass index (BMI).
Results appeared Jan. 16 in the New England Journal of Medicine.
There were 3,083 deaths from all causes over a mean follow-up of 15.8 years, with a maximum follow-up of 36 years among women and 26 years among men. The mean age at death was 74.68 years for women and 78.7 years for men.
The researchers found a J-shaped relationship between BMI at the time of a diabetes diagnosis and risk of death from all causes, with the lowest risk observed among participants with a BMI from 22.5 to 24.9 kg/m2.
The hazard ratios (HRs) for each BMI group were as follows.
- 18.5 to 22.4 kg/m2: HR, 1.29; 95% CI, 1.05 to 1.59;
- 22.5 to 24.9 kg/m2 (reference group): HR, 1.00;
- 25.0 to 27.4 kg/m2: HR, 1.12; 95% CI, 0.98 to 1.29;
- 27.5 to 29.9 kg/m2: HR, 1.09; 95% CI, 0.94 to 1.26;
- 30.0 to 34.9 kg/m2: HR, 1.24; 95% CI, 1.08 to 1.42; and
- ≥35.0 kg/m2: HR, 1.33; 95% CI, 1.14 to 1.55.
When researchers correlated mortality to smoking status, the relationship was linear among participants who had never smoked (HRs across BMI categories, 1.12, 1.00, 1.16, 1.21, 1.36 and 1.56, respectively) but was nonlinear among participants who had ever smoked (HRs across BMI categories, 1.32, 1.00, 1.09, 1.04, 1.14 and 1.21) (P=0.04 for interaction).
There was a direct linear trend in mortality among participants who were younger than 65 when diagnosed with diabetes, but not among those who were 65 years or older at the time of diagnosis (P<0.001 for interaction).
The researchers noted that, although the findings were largely consistent with the results of previous analyses in the general population, they contradict the results of several studies of BMI and mortality that were specific to diabetes.
The researchers wrote, “There was no evidence of a protective effect of overweight or obesity on mortality. In addition, given the relationship of overweight and obesity to other critical public health end points (e.g., cardiovascular disease and cancer), the maintenance of a healthy body weight should remain the cornerstone of diabetes management, irrespective of smoking status.”