I haven't seen any scientific studies suggesting that people with type 2 diabetes, or anyone else, risk elevations in their blood sugar levels when they take glucosamine for the relief of arthritis pain. In fact, the one study of which I am aware found no elevations in blood glucose levels among the type 2 diabetes patients who participated. It was published in the July 14, 2003 issue of the Archives of Internal Medicine. Dr. Jason Theodosakis, M.D., author of The Arthritis Cure, the book that popularized the use of the supplements glucosamine sulfate and chondroitin sulfate for the treatment of osteoarthritis, reports that he has not seen elevations of blood glucose levels in the patients he has treated.
Although glucosamine is derived from glucose, the two substances are not chemically the same and follow different metabolic pathways in the body. While it is unlikely that you'll run into any problems, be sure that your physician knows you're taking glucosamine and monitors your blood glucose levels accordingly.
Taking glucosamine may not affect blood glucose levels directly, but some evidence from both animal and human studies suggests that it may promote insulin resistance over time. When cells lose their sensitivity to insulin, the pancreas overcompensates and cranks out even more insulin, which can lead to weight gain, cardiovascular disease and type 2 diabetes. A three-year clinical trial, sponsored by the National Center for Complementary and Alternative Medicine, has studied this question. The study was completed in June 2006 but results are not yet available. As soon as they are published, I'll post an update.
Andrew Weil , M.D.