More than 1 in 10 American adults have diabetes, and many of them successfully keep their blood sugar levels under control with various medications. Unfortunately, these multibillion-dollar blockbuster drugs haven't proved to be so successful against the biggest cause of death related to diabetes: heart disease. Four new studies published in this week's New England Journal of Medicine bring nothing but disappointing news for diabetics who rely on drugs to lower their risk of heart attacks and strokes. One found that using antihypertensives to lower systolic (the top number) blood pressure below a healthful measurement of 120 mm Hg does nothing to lower a diabetic's risk of heart complications; another found no benefit to adding a drug to raise HDL "good" cholesterol levels in diabetics who were already taking a statin to lower the bad kind. And no heart benefits were associated with two drugs given to lower high blood sugar levels, according to the two other studies.
What all this new evidence suggests is that more may not always be better when it comes to finding ways to prevent heart disease in diabetics. "It's not enough to show that a drug lowers high blood sugar levels or other risky biomarkers," says Steven Nissen, chairman of the department of cardiovascular medicine at the Cleveland Clinic, whose research linked the diabetes drug Avandia with an increased rate of heart attacks. "Does it actually improve clinical outcomes? Does it cause more benefits than risks?"
Evidence is accumulating that diabetics may not benefit—and may even be worse off—when they're treated with medications to drive down their blood sugar levels or blood pressure to normal or below normal levels. The new study examining blood pressure found that diabetics with moderately high blood pressure levels—about 135 mm Hg on average—didn't benefit from taking extra blood pressure medication to lower those levels down to slightly less than 120 mm Hg. In fact, they were more likely than those who kept their levels in the 130s range to experience fainting, heart arrhythmias, and abnormally high potassium levels, all associated with low blood pressure. "Most doctors still aim for a goal blood pressure of 130 or below when treating diabetics, even though no there's no good data to support that," says study leader William Cushman, who is chief of preventive medicine at the VA Medical Center in Memphis. Still, he emphasizes, previous research has shown that diabetics can significantly lower their risk of heart attacks and strokes by getting treated with high blood pressure medications if they have a systolic blood pressure above 140 or a diastolic (lower number) pressure above 90.
The real take-home message here is that those with diabetes shouldn't forget about the importance of lifestyle factors even if they're already achieving optimal blood glucose levels with medications. "We have an abundance of evidence," says Cushman, that losing excess weight, increasing activity levels, and improving nutrition habits will lead to better control of diabetes and lower risks of heart disease. Plus, lifestyle modifications pose none of the side effects or long-term health risks that are associated with blood-sugar-lowering drugs. And these changes appear to be more effective than drugs like metformin at preventing diabetes from occurring in the first place in those who have prediabetes or insulin resistance, according to David Nathan, director of the diabetes Center at Massachusetts General Hospital, who wrote an editorial that accompanied two of the NEJM studies.
Here's a smart action plan:
1. Use drugs wisely. Those with diabetes should take a cholesterol-lowering statin drug to lower their heart-disease risks. They should take a blood pressure medication if they have a level above 140/90 mm Hg to reduce heart disease risks but shouldn't aim to achieve a level below 130 mm Hg for the systolic number, says Cushman. Glucose-lowering medications like metformin should be used to achieve a hemoglobin A1c level—a marker used to determine blood sugar control—of about 7.5 percent. "Personally," he adds, "I'm concerned about driving levels below that with more medication because our previous research found a higher mortality rate in those who had levels as low as 6 percent."