January 21, 2020
2 min read

Fitness more important than low BMI for reducing mortality risk among adults with diabetes

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Adults with diabetes of any BMI have lower mortality risk if they are more physically fit, although the “obesity paradox” still holds for less fit people, according to findings published in Diabetes Care.

“Our results demonstrate that a higher BMI at baseline testing was associated with a lower mortality rate among patients with diabetes predominantly when fitness was low or moderate,” Seamus P. Whelton, MD, MPH, assistant professor of medicine at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease at Johns Hopkins School of Medicine, and colleagues wrote. “Importantly, a higher fitness level was associated with a consistent and significantly lower mortality rate regardless of BMI.”

Whelton and colleagues assessed mortality during a mean of 10 years among 8,528 adults with diabetes (mean age, 57.9 years; 49% women). The researchers also assessed fitness levels using the Bruce protocol exercise treadmill stress test; participants who recorded 10 or more metabolic equivalents (METs) were considered to have high fitness while those who recorded 6 METs to 6.9 METs were considered to have moderate fitness and those who recorded less than 6 METs were considered to have low fitness. The researchers also assessed BMI when the exercise test took place and defined obesity as a BMI of at least 30 kg/m2, overweight as a BMI of 25 kg/m2 to 29.9 kg/m2 and normal weight as a BMI of 18.5 kg/m2 to 24.9 kg/m2.

For participants with obesity vs. those with normal weight, mortality risk was reduced (HR = 0.7; 95% CI, 0.59-0.81), including for those with low fitness (HR = 0.71; 95% CI, 0.57-0.89) and those with moderate fitness (HR = 0.63; 95% CI, 0.47-0.84). Mortality risk was reduced by 4% for each 1 kg/m2 increase in BMI (HR = 0.96; 95% CI, 0.95-0.97).

Diabetes healthy 2019 
Adults with diabetes of any BMI have lower mortality risk if they are more physically fit, although the “obesity paradox” still holds for less fit people.
Source: Adobe Stock

Mortality risk also was reduced for participants with high fitness of normal weight (HR = 0.28; 95% CI, 0.18-0.42), overweight (HR = 0.35; 95% CI, 0.27-0.47) or obesity (HR = 0.28; 95% CI, 0.21-0.37) vs. participants of the same BMI with low fitness. In addition, mortality risk was reduced by 24% for each 1 MET increased in fitness (HR = 0.76; 95% CI, 0.73-0.78).

“Fitness significantly affects the association of BMI and mortality risk among patients with diabetes,” the researchers wrote. “While weight loss and improved fitness should both be recommended for patients with diabetes, these observational results highlight the need for further research to test whether prevention strategies focusing on improving fitness may potentially provide a greater reduction in mortality than weight-loss interventions.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures.