Study: Weight Loss Doesn't Cut Heart Risk for Diabetics

Losing a moderate amount of weight doesn't reduce the risk of heart attack or stroke for obese diabetics, a new study suggests. The study included more than 5,000 adults with type 2 diabetes. Their average weight was 220 pounds when the study started. People were randomly divided into 2 groups. One group went through an intensive program that included a low-calorie diet and 175 minutes of moderate exercise each week. They were given counseling to help them stay with the program. The other group got education about diet and weight loss, but no program. After a year, the first group had lost 8.6% of body weight and the second group less than 1%. By the end of 9.6 years, weight loss was 6% in the first group and 3.5% in the second. Both groups had similar rates of heart attack, stroke and related death. The study was stopped because researchers didn't think continuing would change the results. People in the intensive program did need less medicine to control blood sugar. They also were less likely to develop kidney or eye disease or severe depression. The New England Journal of Medicine published the study online. USA Today and HealthDay News wrote about it June 24.

By Howard LeWine, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

People with diabetes are two to four times more likely to have a heart attack or stroke than those without the disease. And deaths from heart conditions and stroke are the leading causes of death and disability among people with diabetes.

Lifestyle changes have been emphasized as the mainstay of treatment, especially for people with type 2 diabetes. It's well known that sticking with exercise and diet changes helps people with type 2 diabetes get thinner and fitter. And their blood sugar levels move toward the normal range with fewer drugs.

The general assumption has been that you can also lower your risk of heart attack, stroke and related deaths with diet and exercise. But that's not what this new study found. It included more than 5,000 overweight or obese people with type 2 diabetes.

The researchers randomly assigned people to one of two groups:

• Intensive lifestyle changes aimed at a long-term 7% reduction in body weight. To achieve the goal, people were put on reduced-calorie diets and a program of 175 minutes of moderate-intensity exercise per week. They received instruction and coaching to help them.
• Instruction on diet and exercise with minimal ongoing support.

All patients received usual care by their own doctors.

The study was stopped after 9.6 years. That was 4 years earlier than planned. The rates of heart attack, stroke, hospital stays for angina and death related to these diseases were similar in both groups. It was unlikely that continuing the study would have changed the results.

There are several possible reasons that people in the intensive program had heart- and stroke-related outcomes similar to those who received usual care.

• Weight loss clearly helps lower blood sugar. However, it may not play an important role in heart attack and stroke risk.
• By the end of 9.6 years of the study, both groups had lost weight. The group in the intensive program lost more weight on average. Perhaps weight loss matters, but losing those extra pounds did not make enough of a difference in heart attack and stroke risk.
• The people in the usual care group were more likely to be treated with medicines to lower blood pressure and cholesterol. These drugs can decrease the risk of heart attack and stroke.
• The intensive lifestyle change group received instruction to eat a standard low-calorie diet. It was relatively high in carbohydrates and lower in fat. But it was not what today is considered a healthier Mediterranean-style diet.

What Changes Can I Make Now?

Lifestyle changes still are as important as ever for people with diabetes and those at risk for diabetes. Striving for a healthy weight, eating the right foods and exercising regularly:

• Lowers your risk of developing eye disease
• Decreases your chance of having kidney failure
• Improves your quality of life
• Decreases your risk of depression or help lessen symptoms of depression if you already have it

If you have diabetes or are at risk of diabetes, lowering blood sugar and reducing weight only lowers your heart attack and stroke risk a little. As this study and many others show, you also need to:

• Avoid tobacco products
• Keep your blood pressure in the normal range, with medicines if needed. A goal of 130/80 or lower is even better.
• Lower your LDL cholesterol to less than 100 milligrams per deciliter (mg/dL). Closer to 70 mg/dL is even better.

What Can I Expect Looking to the Future?

Diabetes care needs to be tailored to each person. It is not a one-size-fits-all recipe. It's not just about blood sugar control and weight loss. Reducing risk for the many health problems that diabetes can cause must take equal priority.