If you have type 2 diabetes, being slim may not be an advantage (Photo: Reuters)

If you have type 2 diabetes, being slim may not be an advantage, according to a new study, published in the Journal of the American Medical Association on Wednesday. Researchers found that heavier people with diabetes tend to live longer than thinner people.

Researchers looked at 2,600 people with type 2 diabetes, and found that over a period of 10 to 30 years, slimmer people were more likely to die, even after adjusting for factors such as smoking, age and blood pressure.

"This was unexpected given the close association of diabetes with obesity," Mercedes R. Carnethon, study researcher and associate professor of preventive medicine at Northwestern University's Feinberg School of Medicine in Chicago, told WebMD.

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While it was unexpected, it wasn't all that surprising -- researchers have long known about such an "obesity paradox," where heavier people, though more susceptible to disease, are less likely to die from it.

High blood sugar levels in Type 2 diabetes come from patients with pancreas that cannot produce enough insulin, which regulates blood sugar levels. Traditionally, doctors treat Type 2 diabetes with medications and insulin injections. Risk factors for the condition include excess body weight, high cholesterol, low activity and poor diet, according to the National Institutes of Health.

Between 1980 and 2010, the prevalence of diabetes increased 176 percent, according to the Centers for Disease Control and Prevention. One in 12 Americans, 25 million in total, has diabetes according to the CDC. If left untreated, diabetes can lead to kidney failure, blindness, heart disease and nerve damage. The disease was the seventh leading cause of death in the U.S. and cost $174 billion in medical costs, disability and loss of work in 2007, the last year with available data.

While researchers aren't sure why heavier people lived longer, they said it could have something to do with the ratio of body fat to muscle. Muscle utilizes insulin, and people with less muscle are unable to use it properly.

"It could well be that these people do have an adverse body fat distribution. They haven't measured it in this study, so you can't be 100% sure, but it would fit into the general idea that these people have an adverse fat distribution," E. Louise Thomas, PhD, a research scientist at University College London, told WebMD.  "There could be more on the inside."