New study explains why only some obese people get type 2 diabetes

Obesity is widely regarded as the leading risk factor for type 2 diabetes, yet some people who are overweight never develop the metabolic condition. Why is this? The question has plagued scientists and doctors for years, with few satisfactory answers.

Now, a team out of the University of California, Davis reports that other factors, such as high blood pressure and unhealthy cholesterol, may have more to do with a person's diabetes risk than previously thought. Their findings, which were published in the Journal of Clinical Endocrinology and Metabolism, could help shed more light on the subject.

For the study, the team examined fat tissue taken from obese individuals. Some of the participants had a condition known as metabolic syndrome, which is characterized by high blood sugar, hypertension, unhealthy cholesterol and excess abdominal fat. The remaining participants were free of these symptoms, despite being overweight.

The results showed that the fat tissue of the participants with metabolic syndrome released biomarkers associated with insulin resistance and inflammation. These are two of the first symptoms of type 2 diabetes.

This led the researchers to conclude that some aspect of metabolic syndrome must cause changes to the composition of fat tissue that prompt it to release these potentially toxic biomarkers. The findings mean that obesity is likely only dangerous to a person's health when it is accompanied by other metabolic symptoms.

"Our study shows that not all obesity is the same and some body fat may actually be toxic," said Ishwarlal Jialal, MD, PhD and the leader of the study. "We have shown that the dysfunction in the fat of people with metabolic syndrome is more than can be explained by obesity. It tells us that metabolic syndrome is a high-risk condition for people who are obese."

The findings have important implications for assessing health risks in obese individuals. It is widely believed that nearly everyone who is significantly overweight is at risk for developing type 2 diabetes. However, the results of the investigation explain why this may not be true. Enabling doctors to more precisely identify patients who are at the greatest risk could help them to make more meaningful lifestyle recommendations.

Unfortunately, it is relatively unlikely that an obese individual will not have any symptoms of metabolic syndrome. The two conditions often go hand in hand. A recent study conducted by the Centers for Disease Control and Prevention showed that obese men are 32 times more likely to have metabolic syndrome than individuals who are not obese.

The same study estimated that the overall prevalence of metabolic syndrome is 34 percent. Given the high number of people who have the condition, addressing rising type 2 diabetes rates may have to start with tackling the issue of metabolic syndrome. Unless something is done to improve the population's metabolic health, the CDC estimates that one-third of all U.S. adults could have type 2 diabetes by 2050.