Good cholesterol not as protective in people with type 2 diabetes

HDL carries cholesterol out of the arteries, and high levels are associated with a lower risk of heart disease. HDL also helps protect blood vessels by reducing the production of damaging chemicals, increasing the vessels' ability to expand, and repairing damage to the vessel lining.

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, a condition that includes having low HDL levels (under 40 mg/dL in men and 50mg/dL in women). The diabetes patients were taking cholesterol-lowering medication. In laboratory testing, investigators found that the protective benefits on blood vessels were "substantially impaired" in HDL from the diabetic patients.

The diabetics were then randomized to receive either a placebo or extended-release niacin (1500 milligrams/day), a medication that raises HDL cholesterol while reducing other blood fats. After three months, 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.

However, because of the sample size and other factors that can't be excluded, more research is needed to determine if niacin should be recommended for diabetic patients.

Co-lead authors are Sajoscha A. Sorrentino, M.D., and Christian Besler, M.D. Ulf Landmesser, M.D., is the senior and corresponding author.