Second study shows that very tight blood sugar goals may not help diabetics

My patients often come in frustrated when they read about a new study whose results contradict earlier studies. "But I'm doing just what you told me! And now that approach might be wrong?" they may ask. I understand their frustration. In fact, I sometimes share it! But I try to remind myself and them that science is constantly evolving—and this is a good thing. Imagine if scientists never questioned previous studies? Where would we be then? Very far from the cutting edge, that's where. 

Two new studies on diabetes are a good example of a seeming "about face." For years we've told our diabetic patients that the tighter you can control your blood sugar, the better. Now two studies question that assertion. While keeping blood sugar under control is very important, there may not be added benefit to getting aggressive treatment to get very tight control of blood sugar. 

Here, my colleague Dr. Diana Post responds to these new studies:

Pushing blood sugar below current goals does not help the heart for diabetics, an Australian study has found. In the study, one group of patients got standard treatment, while the other took extra medicine to lower blood sugar more. There was no difference between the groups in heart attacks, strokes, or heart-related deaths, though the group with lower blood sugar had one-fifth fewer cases of kidney disease. The study was published online by the New England Journal of Medicine earlier this month.

This is the second study to show that tighter blood sugar guidelines didn't help prevent cardiovascular problems in people with diabetes. In February, a U.S. study reported more deaths in people who were treated to push blood sugar below current goals.

About 21 million Americans have diabetes. Almost 300,000 die each year from health problems caused by the disease.

Most of these deaths are the result of heart disease and stroke. Adults with type 2 diabetes are two- to four- times more likely than non-diabetics to die from heart disease. They also have an increased risk of strokes and damage to arteries in the legs ("poor circulation"). These patients also can develop other problems, such as blindness and kidney failure.

People with type 2 diabetes need to take steps to reduce the risk of further health problems from diabetes. They usually are advised to keep their blood sugar and hemoglobin A1C levels at or near normal. The A1C is a test that shows how well diabetes has been controlled during the last 2 to 3 months.

Doctors have thought that this very tight control of sugars is a good thing. However, it is not clear if this actually leads to better health. Do patients with type 2 diabetes really do better and have fewer health problems if they maintain normal or near-normal blood sugars all the time?

The recent studies

A few months ago, researchers released results from a study of diabetics called the ACCORD study. It enrolled high-risk patients with diabetes and other factors that increase the risk of heart and artery disease.

In this study, very tight control of blood sugar did not reduce the risk of heart attacks or strokes. In fact, more people treated with "tight" sugar control died than people who got the "regular" treatment. It seemed that intensive lowering of blood sugar was too risky for this population.

Now another study, called the ADVANCE study, is being reported. This study also looked at higher-risk diabetics. In the ADVANCE study, tight control of blood sugar lowered the risk of developing kidney problems. It did not lower the risk of heart and artery disease. Unlike the ACCORD study, this study did not find that more intensive control of blood sugar led to higher death rates.

It is not clear yet why more patients in the ACCORD trial with tight control died. We also don't know why that was not seen in the ADVANCE study. Neither study showed that tight control of sugar levels in these high-risk diabetics improved the risk of heart and artery disease.

Many treatments are available to keep diabetes in control, and there are many ways to control other conditions that add to the risk of health problems from diabetes, such as high blood sugar and high cholesterol. If you have diabetes, you can do many things to reduce your risk:

• Get your blood pressure checked. If it is high, speak to your doctor about how to control it. We know that controlling blood pressure can lower the risk of heart attacks and kidney damage in diabetics.
• Make sure your cholesterol is where it should be. Statin medicines lower cholesterol. They can lower the risk for getting a heart attack. People with diabetes sometimes are advised to use these medicines even when they don't have high cholesterol levels. The American Diabetes Association now has guidelines on treating cholesterol in people with diabetes. Review these with your doctor.
• Don't drink sweetened drinks such as soda. These can add to your weight and have a negative effect on your diabetes.
• Don't smoke.
• Exercise regularly.
• Get your eyes checked regularly.
• Ask your doctor if you can benefit from drugs that can help prevent kidney disease. Medicines from the groups known as ACE inhibitors and angiotensin receptor blockers have been shown to help protect kidneys in people with diabetes.

It is becoming clear that just setting "targets" for reducing known risks may not be the best way to help patients live longer and better. The way we achieve the target goals may be just as important. Perhaps the specific medicine or approach used to lower blood sugar is more important than the levels achieved.

Julie K. Silver, M.D., is an assistant professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School. She is also the Chief Editor of Books for Harvard Health Publications.

Diabetes

Nearly 21 million Americans suffer from diabetes, and as anyone who has been affected by the disorder knows, it is about much more than a statistic: it means a new way of life. Diabetes: A plan for livingis a special report from Harvard Medical School that will help you learn how to better understand and manage your diabetes, including type 1 and type 2, as well as other variations of the disease. This report will show you that it's not just possible to live with diabetes; it's possible to live well.

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