BEDFORD, Mass—When the controversial Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) showed that the supplements had little efficacy in osteoarthritis (OA), many proponents argued the merits of the study and contended that at least the supplements were safe, unlike nonsteroidal anti-inflammatory drugs.  Now a new study suggests that people with untreated diabetes who take glucosamine may experience spikes in glucose levels when they take glucosamine. The study appears in the online issue of the Annals of Rheumatic Disease.1

"There are probably millions of people out there who have diabetes and don't know it and an awful lot of people are taking glucosamine and have been for years," lead study author Jeremiah E. Silbert, MD, told CIAOMed. Dr. Silbert is director of the connective tissue research laboratory at the Bedford Veteran's Affairs Hospital in Bedford, Massachusetts, and a professor of medicine at Harvard Medical School in Boston.

"Our results suggest that people who have diabetes and don't know it, or who have glucose intolerance, seem to get spikes in glucose when they take glucosamine."
—Jeremiah E. Silbert, MD
"Our results suggest that people who have diabetes and don't know it, or who have glucose intolerance, seem to get spikes in glucose when they take glucosamine," Dr. Silbert cautions.

Given the lack of efficacy of glucosamine seen in large clinical trials, "there is no reason to take it in the first place, and now we can't say it doesn't do anything harmful [because] maybe it does," he emphasized.

Exactly how glucosamine affects glucose in this subgroup is not fully understood, Dr. Silbert continued. "There are some suggestions that it has an effect on insulin receptors on cells and glucosamine and glucose are both metabolized by the liver in similar ways and the two are competitive."

Researchers took blood from 16 overnight-fasted subjects with OA but no other diagnosed medical condition every 15-30 minutes during 3 hours of continued fasting and during 3 hours after ingestion of 75 grams of glucose with or without ingestion of 1500 mg of glucosamine sulphate. They analyzed glucose and measured by radioimmunoassay every 30 minutes for 2 hours.

Three participants who were found to have previously undiagnosed abnormalities of glucose tolerance showed statistically significant incremental elevations in glucose levels following ingestion of glucosamine sulphate. The other 13 participants also had mean incremental elevations, but they were not statistically significant. Glucosamine sulphate ingestion had no effect on insulin levels, the study showed.

"More studies are needed to confirm these findings," Dr. Silbert said.

Reference

1.Biggee BA, Blinn CM, Nuite M, et al. Effects of oral glucosamine soleplate on serum glucose and insulin during oral glucose tolerance subjects with osteoarthritis. Ann Rheum Dis. Published Online: 3 July 2006. doi:10.1136/ard.2006.058222.