Jan. 28, 2013 -- People with diabetes who want to lower their risk of heart attack and stroke should focus on controlling their blood pressure and ''bad'' cholesterol, according to a new study of more than 26,000 patients.
Controlling both these risk factors, the researchers found, made patients less likely to be hospitalized for heart attacks or strokes than those who only controlled blood sugar during the six-year follow-up.
"It's not that blood glucose is not important. It's that low-density cholesterol and blood pressure control are more important if cardiovascular disease is what you are trying to prevent," says Gregory A. Nichols, PhD, a senior investigator at Kaiser Permanente Center for Health Research.
The study is published in the Journal of General Internal Medicine.
Diabetes & Heart Disease: Study Details
More than 18 million people in the U.S. have diabetes, according to the American Diabetes Association.
Those with type 2 diabetes (in which the body doesn't make enough insulin or use it properly) have a higher risk of heart disease and stroke.
However, Nichols says, he is not aware of any study that looked at the contribution of these risk factors to heart attack or stroke risk among people with diabetes.
For the new study, the researchers calculated all patients' average values on systolic blood pressure (the upper number of the reading), cholesterol, and blood sugar levels.
"There were actually eight different possible categories," Nichols says. These ranged from having none of the risk factors under control to having all of them under control.
Guidelines suggest that systolic blood pressure in those with type 2 diabetes should be less than 130.
"LDL ideally is less than 100 [mg/dL] and A1c [a blood sugar measure] is less than 7%," Nichols says.
Next, they looked at whether the patients had a hospital admission with a diagnosis of heart disease or stroke. During the study, 1,943 patients were hospitalized for those reasons.
Those who were in the hospital were on average 65 years old. Those who were not were on average 58.
Nichols looked at the risk factor status of all patients.
Diabetes & Heart Disease Risk: Results
"People who had all three risk factors under control or only blood pressure and LDL under control were about three times less likely to be hospitalized," he says.
Most likely to be hospitalized were those who had none of the risk factors under control or only blood sugar under control, Nichols says.
However, on average, both those hospitalized and those not had the same average blood sugar level, 7.3%.
The link between poor blood pressure and cholesterol control and heart attack or stroke held, Nichols says, even after taking into account pre-existing disease and other factors that might play a role.
The study shows that ''we just didn't see any additional benefit to getting it below 7," says Nichols of the blood sugar.
"To me the take-home message is yes, diabetes is defined by high blood sugar. But that is not the only thing you need to pay attention to."
Diabetes & Heart Disease Risk: Perspective
''We are clearly doing better [in reducing heart attack and stroke] by taking care of blood pressure and cholesterol," says Robert Ratner, MD, chief scientific and medical officer for the American Diabetes Association.
"They have huge impacts on survival and cardiac events," he says, citing research. "That doesn't mean glucose isn't important."
The protective effects of blood sugar control on heart disease take longer to kick in, according to Ratner, ''and probably aren't as apparent as blood pressure and cholesterol [effects]."
Controlling all three risks is important, he says. "If you begin to ignore one, it's going to start having a deleterious effect on cardiovascular disease risk."
"It's a large study, and that is a strength," says Om Ganda, MD, director of the Lipid Clinic at Joslin Diabetes Center and associate professor of medicine at Harvard Medical School.
But he says that the other diseases in the patients studied ''make it impossible to detect the effects of blood sugar control."
''The glucose [control] effect is very slow, compared to cholesterol and blood pressure," Ganda agrees.
To him, the findings stress the importance of early diagnosis, when blood sugar can be addressed right away.
"Once you have established cardiovascular disease or once you have diabetes for a fairly long duration,'' he says,"indeed, glucose control may not be as important as in the early stages of diabetes."
Funding was provided by AstraZeneca, which makes cholesterol-lowering medicine, and Bristol-Myers Squibb, which makes blood pressure-lowering medicine.
Two study co-authors are AstraZeneca employees and shareholders. Nichols controlled the data.