Recent studies suggesting that heavier people with diabetes have lower death rates than normal weight patients may be a myth.
A strong body of research shows that being overweight or obese puts people at risk for chronic conditions like heart disease, diabetes, cancer and even early death. But several small studies connecting obesity to a protective effect against type 2 diabetes-related death have raised questions about a possible ‘obesity paradox,’ and whether weight can be a benefit in preventing progression of the disease. A 2012 study published in the journal JAMA, for example, studied 2,625 people recently diagnosed with type 2 diabetes, of which only 12% were normal weight. But the larger people with diabetes lived longer than their thinner peers.
Why the heavier people lived longer wasn’t clear; the researchers speculated that genetics, or the type of fat that certain obese people accumulated compared to normal weight individuals could be responsible.
But in a new study published in the New England Journal of Medicine, scientists say that’s unlikely. “We didn’t see this protective effect at all,” the study’s leader, Diedre Tobias of the Harvard School of Public Health, told the Associated Press. “The lowest risk was seen in the normal-weight category.”
Tobias and her colleagues looked at 11,427 female nurses and male health professionals who were diagnosed with diabetes. They were divided into groups based on their body mass index (BMI), with those with a BMI over 25 considered overweight and people with a BMI over 30 considered obese. After 15 years, the scientists recorded the participants’ death rates and found that those with BMI in the 22.5 to 25 range, considered normal weight, had the lowest risk of diabetes-related death.
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The researchers also looked at subgroups within the study population and found that for people younger than 65, their risk of dying from diabetes rose with weight, and the same trend was seen among non-smokers (smokers have higher death rates overall).
The findings should dispel the idea that staying heavy will lower the risk of complications related to diabetes; the size of the study and the consistent trend of rising mortality linked to climbing weight confirm that extra pounds are a major risk factor for dying from the disease. While being slightly overweight did not significantly raise the risk of diabetes-related death, doctors note that once patients start to put on pounds, it’s hard to keep them off. So the advice they have been giving patients for years still holds — to avoid complications from chronic illnesses like diabetes and heart disease, it’s best to keep BMI down.