Fat Builds Up in Hearts Before Diabetes Onset

Fat starts to build up in the hearts of pre-diabetic people before either diabetes or heart disease symptoms appear, according to a new study.

Researchers at the University of Texas Southwestern Medical Center discovered the fatty buildup using a simple imaging technique that could become a new screening tool for people at risk for diabetes and heart disease.

Prior research has shown that fat builds up in the hearts of people with heart failure or type 2 diabetes, but they did not know whether the fat deposits occurred before or after diabetes developed. The challenge was to find a way to get a static image of the human heart, which is always in motion.

"Hearts beat; people breathe; and magnetic resonance imaging is very sensitive to motion, so we had to find a way to electronically freeze the image of the heart," senior author Dr. Lidia Szczepaniak said in a prepared statement.

Writing in the Sept. 4 issue of Circulation, Szczepaniak and her team described a technique that uses an ordinary MRI system with the addition of computer software that converts the signals from a moving heart into a still image.

Using this method, they examined the heart images of lean and obese people with normal blood sugar, obese people beginning to show abnormal sugar levels, and obese people with type 2 diabetes. In addition to learning that fat buildup occurs before diabetes, the researchers also found that people with an abnormal sugar metabolism had significantly higher levels of fat in their heart than people with normal blood sugar, regardless of body weight.

While the amount of fat in the heart was unrelated to the amount of fat in the bloodstream or liver, it did correspond to the amount of fat in the stomach region. The buildup of fat in heart cells is important to identify and prevent, because heart cells are not replaced after they die, according to the researchers. Excess fat in the heart may slowly kill the organ, they said.