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March 22, 2010
Insights into Managing Type 2 Diabetes
Adults with type 2 diabetes are over twice as likely to die from heart disease as those without diabetes. But studies about how tightly to manage blood pressure and lipid levels have been inconclusive. Two related clinical trials will now help guide doctors.
The landmark Action to Control Cardiovascular Risk in Diabetes (ACCORD) clinical trial is one of the largest studies ever conducted in adults with type 2 diabetes who are at especially high risk of cardiovascular events, such as heart attacks, stroke or death from cardiovascular disease. The multicenter clinical trial tested 3 strategies to lower the risk of major cardiovascular events: intensive control of blood sugar, intensive control of blood pressure and treatment of multiple blood lipids.
ACCORD researchers from 77 medical centers in the United States and Canada studied over 10,000 participants between the ages of 40 and 79 who had type 2 diabetes for an average of 10 years. The participants had pre-existing cardiovascular disease, evidence of subclinical cardiovascular disease, or at least 2 cardiovascular disease risk factors in addition to diabetes. All the participants were enrolled in the ACCORD blood sugar treatment clinical trial and maintained good control of blood sugar levels during the study. In addition, participants were enrolled in either the blood pressure trial or the lipid trial and were treated and followed for an average of about 5 years. The study was sponsored primarily by NIH's National Heart, Lung and Blood Institute (NHLBI).
Results of the ACCORD blood sugar clinical trial were reported in 2008. That trial found that intensively lowering blood sugar to near-normal levels brought a higher risk of death for participants than standard blood sugar control.
The latest results appeared online in 2 reports on March 14, 2010, in the New England Journal of Medicine. In the blood pressure trial, researchers randomly assigned over 4,700 participants with elevated blood pressure to a target systolic blood pressure of either less than 140 mmHg (the standard group) or a normal level of less than 120 mmHg (the intensive group). A variety of medications was used to reach blood pressure goals. The study found that lowering blood pressure to normal levels doesn’t significantly reduce the risk of cardiovascular events overall, although it may reduce the risk of stroke.
In the lipid trial, researchers compared the cardiovascular effects of a statin (simvastatin) to combination therapy of a statin and a fibrate (fenofibrate) in over 5,500 participants. Both statins and fibrates are used to treat abnormal levels of blood lipids. Statins lower LDL, or "bad" cholesterol, and are proven to lower cardiovascular disease risk in people with diabetes. Fibrates primarily lower fats in the blood known as triglycerides and raise HDL, or "good," cholesterol.
Combination therapy appeared to be safe, but didn’t lower the risk of heart attack, stroke or death from cardiovascular disease more than statins alone. "Although our analysis suggests that certain patients may benefit from combination therapy, this study provides important information that should spare many people with diabetes unneeded therapy with fibrates," says Dr. Henry Ginsberg of Columbia University, lead author of the lipid trial.
"ACCORD provides important evidence to help guide treatment recommendations for adults with type 2 diabetes who have had a heart attack or stroke or who are otherwise at especially high risk for cardiovascular disease," says acting NHLBI director Dr. Susan B. Shurin.
It's important to note that the treatments used in the standard control groups have previously been shown to be effective. The findings don’t detract from the fact that controlling blood pressure and LDL cholesterol levels can reduce cardiovascular risk—not only for people with diabetes, but for everyone.