Type 1 diabetes has long been considered a thin person’s disease, but a new study challenges that notion.

About 62% of adults with type 1 diabetes were overweight or obese, the researchers found. That compared to 64% of those without diabetes and 86% of those with type 2 diabetes.

For the study, the researchers used data on more than 128,000 people from the U.S. National Health Interview Survey.

The investigators found that 34% of adults with type 1 diabetes were overweight. About 28% had obesity.

Despite these high numbers, only slightly more than half of adults with type 1 diabetes who were overweight or had obesity received lifestyle recommendations from health care providers, such as to increase physical activity or cut calories, the findings showed.

The study authors said this is likely because the insulin required to treat type 1 diabetes carries the risk of dangerously low blood sugar levels (hypoglycemia) if combined with intense exercise or severely reduced calorie intake.

“The lack of evidence for safe, effective methods of diet- and exercise-based weight control in people with type 1 diabetes may be keeping doctors from recommending such methods,” said study first author Michael Fang, an assistant professor in Johns Hopkins’ Bloomberg School of Public Health, in Baltimore. “Large clinical trials have been done in type 2 diabetes patients to establish guidelines for diet- and exercise-based weight management, and we now need something similar for type 1 diabetes patients.”

While people with type 1 diabetes were strongly affected by the overweight and obesity epidemic in the United States, they aren’t being advised to control their weight to the same extent as people with type 2 diabetes.

“Our study busts the myth that people with type 1 diabetes are not being affected by the global obesity epidemic,“ senior study author Elizabeth Selvin, a professor in the Bloomberg School’s department of epidemiology, said in a Hopkins news release. “These findings should be a wake-up call that we need to be aggressive in addressing the obesity epidemic in persons with type 1 diabetes.”

Type 1 diabetes is an autoimmune condition that often develops in childhood, though it can also occur in adults. Type 2 diabetes is common in older adults and those who are overweight.

In type 1, a person’s immune system mistakenly attacks and destroys pancreatic cells that produce insulin. This is the essential hormone that directs cells to take up glucose from the blood.

About 1.6 million American adults aged 20 and up have type 1 diabetes, according to the U.S. Centers for Disease Control and Prevention. They must rely on an insulin pump or insulin injections.

While being overweight can bring increased risk for a range of serious health conditions, patients with type 1 diabetes may have additional risks. For example, obesity tends to make the body less sensitive to insulin. This could mean needing higher insulin doses or having less predictable blood glucose responses.

The findings were published online Feb. 14 in a research letter in the Annals of Internal Medicine. Support for the research was provided by the U.S. National Heart, Lung, and Blood Institute.

More information

The U.S. Centers for Disease Control and Prevention has more on type 1 diabetes.

SOURCE: Johns Hopkins Bloomberg School of Public Health, news release, Feb. 13, 2023