Increasing levels of high-density lipoproteins, better known as HDL or "good" cholesterol, reduced the risk for heart attack and stroke among patients with diabetes, according to a new study.
The observational study, one of the largest of its kind, examined the medical records of more than 30,000 patients with diabetes and also found that patients whose HDL levels decreased had more heart attacks and strokes.
Researchers studied patients with diabetes because they are more prone to heart disease with a lifetime risk as high as 87 percent.
While there is considerable evidence that reducing the amount of low-density lipoprotein, also known as LDL or "bad" cholesterol, can reduce the risk of heart disease, the relationship between HDL cholesterol and heart disease is less clear.
"Our study adds to the growing body of evidence that raising HDL levels may be an important strategy for reducing heart attack risk," said study lead author Gregory Nichols, PhD, senior investigator with the Kaiser Permanente Centre for Health Research in Portland, Ore.
The study included 30,067 patients who entered Kaiser Permanente diabetes registries in Oregon, Washington and Georgia between 2001 and 2006. These patients had at least two HDL cholesterol measurements between 6 and 24 months apart.
After obtaining the cholesterol measurement, researchers followed the patients for up to 8 years to see if they were hospitalized for a heart attack or stroke.
Most patients (61 percent) had no significant change in HDL levels; in 22 percent of patients, HDL levels increased by at least 6.5 mg/dl (milligrams per deciliter of blood); in 17 percent of patients, HDL levels decreased by at least that same amount.
The study found that patients whose HDL levels increased had 8 percent fewer heart attacks and strokes than patients whose HDL levels remained the same, while patients whose HDL levels decreased had 11 percent more heart attacks and strokes.
Gregory A. Nichols, Suma Vupputuri, A. Gabriela Rosales. Change in High-Density Lipoprotein Cholesterol and Risk of Subsequent Hospitalization for Coronary Artery Disease or Stroke Among Patients With Type 2 Diabetes Mellitus. The American Journal of Cardiology, Volume 108, Issue 8, 15 October 2011, Pages 1124-1128 DOI: 10.1016/j.amjcard.2011.05.047