CHICAGO (Reuters) - Drugs used to control diabetes do not reduce signs of inflammation that are linked with heart disease, U.S. researchers said on Tuesday in a study that reinforces the need for diet and exercise.
Both heart disease and diabetes are inflammatory diseases, and researchers had assumed that controlling diabetes would have an effect.
"At the time we initiated the trial, we were thinking if we treat the diabetes, we will lower inflammation," said Dr. Aruna Pradhan of Brigham and Women's Hospital and Harvard Medical School in Boston, whose study appears in the Journal of the American Medical Association.
"This study suggests that lowering glucose alone does not impact one important risk factor for heart disease, and that is inflammation," Pradhan said in a telephone interview.
She said the data may help explain the findings of a number of large studies in diabetics that found aggressive control of blood glucose did little to protect against heart attacks and stroke.
"Just simply treating diabetes does not seem to have a benefit at preventing these vascular events," she said.
An estimated 23.6 million people in the United States and 246 million people globally have diabetes. Most have type 2 diabetes, the kind linked with a poor diet and lack of exercise.
Adults with diabetes are two to four times more likely to have heart disease or suffer a stroke than people without diabetes. Seventy-five percent of diabetics die from heart disease or stroke, according to the American Heart Association.
Pradhan and colleagues studied 500 people with type 2 diabetes to see whether insulin, or the common diabetes pill metformin, or both could lower levels of inflammatory markers such as C-reactive protein, an immune chemical called interleukin-6, and soluble tumor necrosis factor receptor 2 or sTNFr2, which plays a role in autoimmune disease.
People in the study got insulin plus a placebo pill, metformin alone or metformin plus insulin.
After 14 weeks, the team found the drugs helped lower blood glucose levels, but had little effect on inflammation.
Pradhan said everyone in the study was obese, with a body mass index of 36. BMI is equal to weight in kilograms divided by height in meters squared. Someone with a BMI of 25 to 29 is classified as overweight; 30 and over is considered obese.
While treating diabetes alone may not reduce inflammation, a study last November showed that taking AstraZeneca's cholesterol fighter Crestor, a statin, had a powerful effect at reducing deaths, heart attacks and strokes in people who had normal cholesterol but high levels of C-reactive protein.
Pradhan said her study confirms the need for diabetics to exercise and have a healthy diet and weight. Some may also need to take statins and aspirin to control their heart disease risk.
And she said diabetics still need to control their blood sugar to reduce other complications such as eye and kidney problems, and damage to blood vessels that can lead to amputations.
SOURCE: Journal of the American Medical Association, September 16, 2009.
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