Glucosamine for osteoarthritis: part II, biologic and metabolic controversies.

Glucosamine is a popular nutritional supplement, discussed in clinical offices, peer-reviewed literature, and the media. Despite its popularity, much information is still needed regarding its biological effect in-vivo and its effects on glucose metabolism. The biologic effects of other constituents such as sulfate, chondroitin sulfate, and other additives need to be investigated as well.