It seemed like a good idea. Diabetics are at an unusually high risk of heart disease, heart attack and stroke, so sharply reducing their blood pressure, cholesterol and blood sugar should be highly beneficial. But a decade of studies of thousands of patients show that is not the case.
Two new reports from a major nationwide trial called ACCORD released Sunday show that lowering either blood pressure or cholesterol below current guidelines does not provide additional benefit and, in fact, increases the risk of side effects. A third arm of the study, released two years ago, shows that excessively lowering blood sugar levels actually increases the risk of heart disease.
The results are disappointing, researchers say, because they suggest that clinicians may have reached the limit of what they can do for diabetic patients without developing new therapeutic approaches.
But the good news is, the findings "reduce the cost and potential side effects of drug therapy" and mean that patients will not have to work as hard at reducing blood sugars, lipids and blood pressure, said Dr. Denise Simons-Morton of the National Heart, Lung and Blood Institute, which funded the trial.
"The take-home message is that the standard care approaches are pretty good. If we try to go beyond them, it doesn't provide additional benefit," she said.
Diabetes has become a tremendous problem in the United States, with at least 21 million people afflicted with Type 2 diabetes -- in which cells do not respond properly to insulin produced by the pancreas -- and millions more at risk because of obesity. Most diabetics also have high blood pressure and high cholesterol, factors that raise their risk of heart attack and stroke to the same level as that of people who already have suffered a heart attack.
Many doctors have reasoned that aggressively lowering blood pressure and lipids below nationally recommended levels might decrease the risk of heart disease, and ACCORD, or Action to Control Cardiovascular Risk in Diabetes, was created to study the possibility.
In one arm of the study, Dr. William C. Cushman of the Veterans Affairs Medical Center in Memphis, Tenn., and his colleagues at 77 medical centers enrolled 4,733 Type 2 diabetics with high cholesterol and cardiovascular disease or a high risk of developing it. They were randomly assigned to treatment regimens to lower their systolic blood pressure -- the top number in a blood pressure measurement -- below 140 mm Hg, the standard treatment goal for diabetics, or below 120 mm Hg, the target goal.
Patients in the intensive treatment group took an average of 3.6 medications to lower blood pressure, and those in the normal treatment group took two.
Cushman reported Sunday at an Atlanta meeting of the American College of Cardiology and in a paper published online in the New England Journal of Medicine that the treatment group achieved an average systolic blood pressure of 119 mm Hg but had no decrease in heart attacks, cardiovascular disease or deaths.
Patients did have fewer strokes, 62 in the normal treatment group compared with 36 in the intensive treatment group, but that was offset by such side effects as abnormally low blood pressure or high levels of potassium. Some laboratory measures of kidney function were also abnormal in the intensive treatment group, although there was no increase in kidney failure.
Thus, "the main conclusion to draw from this study must be that a systolic blood pressure target below 120 mm Hg in patients with Type 2 diabetes is not justified by the evidence," wrote Dr. Peter M. Nilsson of University Hospital in Malmo, Sweden, in an editorial accompanying the report.
In the second arm of the study, Dr. Henry N. Ginsberg of the Columbia University College of Physicians and Surgeons studied 5,518 similar patients with high cholesterol levels. One group was given the cholesterol-lowering drug simvastatin, and the second group was given both simvastatin and a fibrate, a class of drug that lowers cholesterol and increases levels of high-density lipoproteins or HDL, the so-called good cholesterol.
Ginsberg reported at the meeting and in a separate paper in the New England Journal that the addition of fibrate to the regimen provided no benefit on any measure. There was a trend toward a benefit in patients with the highest cholesterol and the lowest HDL levels, but that group was not large enough for the results to be statistically significant.
"My personal opinion is that we need to put more effort into prevention," Simons-Morton said. "If we prevent diabetes in the first place, we reduce risk. Once they have diabetes and risk factors, we are never going to treat down to a level of risk as if they never had diabetes."