Diabetes Reduces the Heart-protective Effects of High-density Lipoprotein

According to a press release from the American Heart Association, researchers at the University Hospital Zurich and the Medical School of Hannover in Germany and Switzerland compared the vessel-protecting action of HDL taken from 10 healthy adults with that of 33 patients who had type 2 diabetes and metabolic syndrome and found that “the protective benefits on blood vessels were ‘substantially impaired’ in HDL from the diabetic patients,” even in patients who were taking cholesterol-lowering medication.

Patients with diabetes were given either a placebo or 1500 mg/day of extended-release (ER) niacin for three months, at which point the researchers found that “patients receiving extended-release niacin had increased HDL levels, and markedly improved protective functions of HDL in laboratory testing as well as improved vascular function.”

The results of this study were published online ahead of print on the website of Circulation: The Journal of the American Heart Association. In the abstract, the authors of the study note that “HDL from healthy subjects stimulatedendothelial nitric oxide production, reduced endothelial oxidantstress, and improved endothelium-dependent vasodilation andearly endothelial progenitor cell—mediated endothelialrepair. In contrast, these beneficial endothelial effects ofHDL were not observed in HDL from diabetic patients, which suggests markedly impaired endothelial-protective properties of HDL. ER niacin therapy improved the capacity of HDL to stimulateendothelial nitric oxide, to reduce superoxide production, andto promote endothelial progenitor cell–mediated endothelialrepair. Further measurements suggested increased lipid oxidationof HDL in diabetic patients, and a reduction after ER niacin therapy.”

Researchers have found that so-called “good cholesterol” (high-density lipoprotein, or HDL), has less heart-protective and blood vessel-protective effects in people with type 2 diabetes.