Type 2 diabetes, a condition widely thought of as a disease of the overweight and sedentary, also develops in people who aren’t overweight. And it may be deadlier in these normal-weight people, a new study shows.

In the study, which appeared in The Journal of the American Medical Association, researchers reviewed data involving more than 2,500 people with Type 2 diabetes, some of whom were followed for decades. The scientists found that those who were of normal weight around the time of their diagnoses were twice as likely to die during the study period, compared with those who were overweight or obese.

The researchers could not explain why having a greater body mass index, or B.M.I., might protect someone with diabetes. But they did point out that some doctors may be prone to treating thin diabetics differently from their obese counterparts, and may be less likely to push them to make diet and exercise changes that could improve their survival.

“Normal-weight people may be treated less aggressively,” said Mercedes R. Carnethon, an author of the study and an associate professor of preventive medicine at the Northwestern University Feinberg School of Medicine. “This really is an argument to treat a normal-weight person with diabetes as aggressively as you would treat an overweight or obese person with diabetes.”

The findings also provide evidence that patients with Type 2 diabetes may display what researchers call the obesity paradox, the observation that people with certain chronic diseases tend to have lower mortality rates if they carry excess pounds. The phenomenon has been documented previously in people with heart failure, hypertension and kidney disease.

“We thought perhaps that the obesity paradox wouldn’t apply to this population, given the strong association between overweight and diabetes,” Dr. Carnethon said.

Treatment of Obesity: An Overview
Obesity and type 2 diabetes commonly co - occur. Weight loss is associated with significant health benefits, including improved glycemic control and reduced blood pressure. This article reviews approaches to the treatment of obesity, considers special issues relevant to obese patients with type 2 diabetes, and presents suggestions for the prevention of obesity.

To be overweight in the United States is to be a member of the majority. Recent data indicate that fully 64% of American adults are either overweight (body mass index [BMI] = 25.0–29.9 kg/m²) or obese (BMI ≤30 kg/m²). These figures represent a sharp increase over the value of 55% in 1994 and reflect a doubling in the rate of obesity since 1980 (i.e., from 15 to 30%). The World Health Organization has labeled obesity a global epidemic; indeed, a recent report estimated that 1 billion people worldwide are overweight and 300 million are obese. In the United States, obesity has been estimated to cost approximately $99 billion a year, principally through its association with cardiovascular disease, type 2 diabetes, and some types of cancer.

There is good news amidst these alarming statistics - small weight losses can have large health benefits. Recent studies have shown that a 5–10% reduction in initial weight is associated with significant improvements in blood pressure, cholesterol levels, and glycemic control.

Results of the Diabetes Prevention Program (DPP) have provided the most definitive evidence to date of the health benefits of modest weight loss. More than 3,200 overweight individuals with impaired glucose tolerance (IGT) were randomly assigned to one of three conditions: 1) placebo; 2) metformin (Glucophage, 850 mg/day); or 3) a lifestyle intervention designed to induce a loss of 7% of initial weight and to increase physical activity to ≤150 minutes per week. Participants were treated for up to 4 years. The maximum weight loss in lifestyle-treated patients was ~7 kg (at month 6), which declined to ~4 kg (at year 4). As shown in Figure 1, participation in the lifestyle intervention reduced the risk of developing type 2 diabetes by 58% compared with placebo and by 39% compared with metformin. The preventive effect of lifestyle intervention held for members of both sexes and all racial and ethnic groups.

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  Anthony N. Fabricatore, PhD and
  Thomas A. Wadden, PhD