"Many people take glucosamine for arthritis-like symptoms and, from previous research, we thought glucosamine may also have a beneficial effect on HDL cholesterol," Dr. Stewart G. Albert noted in comments to Reuters Health.

Albert, from Saint Louis University School of Medicine, Missouri, and his colleagues evaluated the effects of glucosamine (500 milligrams taken three times daily) versus matching "placebo" capsules in ten people with type 2 diabetes and two with type 1 diabetes.

The three men and nine women in the study, all with low HDL cholesterol, were randomly assigned to take glucosamine or placebo for 2 weeks, and then to cross over to a 2-week course of the alternate therapy.

"We did not find any benefit of glucosamine on HDL cholesterol or any worsening of the diabetes control," Albert said.

In their report of the study in the journal Diabetes Care, the investigators note that the lack of an effect on diabetes control "is consistent with previously published studies on the effect of glucosamine in both diabetic and nondiabetic individuals."

However, "This study does not answer whether higher doses or longer duration of glucosamine may make any difference" to HDL levels, Albert said.