Fat Forms in Heart Before Diabetes

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Cardiac steatosis in diabetes mellitus, by J.M. McGavock and colleagues. Circulation 116: 1170-1175, 2007

What is the problem and what is known about it so far?

People who have diabetes are more likely to have a heart attack or develop other forms of cardiovascular disease (CVD, disease of the heart and blood vessels). The chance of CVD among people with diabetes seems greater than can be accounted for by high blood pressure or coronary artery disease (disease of the heart’s blood vessels).

But scientists are unsure what imbalances may lead to CVD.

Why did the researchers do this particular study?

One idea about why CVD is more common in people with diabetes is that more fats may be stored in the heart. The researchers wanted to measure the levels of fats within muscle cells of the heart in normal people, people with pre-diabetes, and people with diabetes.

Who was studied?

The study included 177 people who represent a range of stages in the progression of diabetes: lean and with normal blood glucose levels, overweight or obese but with normal blood glucose levels, pre-diabetes, and diabetes.

How was the study done?

Each participant had blood drawn for tests and underwent a special magnetic resonance imaging (MRI) test. The MRI test measured levels of triglycerides—a type of fat used by researchers to indicate how much fat is being stored in heart muscle.

What did the researchers find?

Researchers found that triglyceride levels in heart muscle were 2.3 times higher in people with pre-diabetes and 2.1 times higher in people with diabetes compared with people who are lean and had normal blood glucose levels.

What are the limitations of the study?

It isn’t known whether high levels of fats in heart muscle is a cause of CVD or a consequence of the disease. There could be other things contributing to CVD. Some people with diabetes were treated with insulin, which affects how fats are handled by the body and which may have influenced the results.

What are the implications of the study?

The signs of CVD are evident very early in people with pre-diabetes and diabetes. An MRI to measure levels of triglycerides in heart muscle may be useful to identify people most likely to develop CVD and who could benefit most from early and aggressive treatment.