For years, doctors have pondered why some thin individuals develop type 2 diabetes, while certain obese people aren’t stricken with the blood sugar disorder. Now, new findings published in the journal Cell Metabolism show that a buildup of toxic fats in the blood may make some folks more prone to developing the metabolic condition—regardless of their weight, body type or dietary disposition, ScienceDaily reports.

Type 2 diabetes occurs when the pancreas does not make enough insulin, a hormone that helps regulate blood sugar in the body. While numerous studies show that being overweight, eating an unhealthy diet or consuming excessive amounts of sweets can dramatically increase a person’s likelihood of acquiring the disorder, these risk factors don’t automatically lead to diabetes for everyone, which has perplexed the health care community for decades.

For the three-year study, researchers at the University of Utah’s College of Health reviewed health data from a group of obese patients in Singapore who underwent gastric bypass surgery. Some individuals suffered from type 2 diabetes and some didn’t. Scientists found that patients who didn’t suffer from type 2 diabetes had fewer ceramides in their fat tissue. (Ceramides are a toxic class of metabolites that may make people prone to type 2 diabetes.)

Scientists theorized that ceramides—which affect the way the body handles nutrients—could push excess fat into the bloodstream and disrupt metabolic function. To test this theory, researchers added excess ceramides to the fat cells of humanized mice to see its effects. Researchers found that the addition of these substances eventually caused the rodents to become unresponsive to insulin and impaired their ability to burn calories.

“Some people are just not made to deal with dietary fat,” said Scott Summers, PhD, chairman of the University of Utah’s Department of Nutrition and Integrative Physiology and an author of the study. “It’s not just how much you eat, because some people can eat a lot and they just store all the fat effectively and remain healthy.”

Researchers suggested the findings also show that high ceramide levels may increase diabetes risk, while low levels might help protect against the disease. As a result of the new research, scientists are now searching for possible genetic mutations that can predispose individuals to accumulate these toxic molecules in their blood.

To learn more about how genetics can help influence your type 2 diabetes risk, click here.