A short-term study on the supplement glucosamine-chondroitin sulfate (Glu-CS) in dogs found no link to diabetes mellitus or to an increase in serum fructosamine.

The researchers gave 12 healthy adult dogs Glu-CS supplements and a placebo orally for 21 days each. They found that the supplements did not significantly change the serum fructosamine levels of the dogs. The study cites some concern among veterinarians that glucosamine supplements can either affect glycemic control in diabetic patients, or may even cause diabetes mellitus.

However, none of the dogs in the study developed diabetes mellitus, and the changes noted in serum fructosamine concentration after the supplements were given did not differ significantly from the effects of the placebo.

Joe Bartges, DVM, PhD, DACVIM, DACVN, is professor of medicine and nutrition at the University of Tennessee College of Veterinary Medicine. Bartges said that he recommends glucosamine supplements, especially in larger dogs that are prone to osteoarthritis. He said he has not personally seen any problems with diabetic dogs taking glucosamine, but there is some concern.

“The concern is it has not been proven yet in dogs or humans,” he said. “The only study in humans was over 90 days (rather than 21 days) and did not find a problem with glucosamine administration.”

That study, from 2003, looked at glucosamine-chondroitin supplement use in human patients with type 2 diabetes mellitus. It set out to find whether the supplements would affect glycemic control in these patients, and after 90 days it did not.

“Oral glucosamine supplementation does not result in clinically significant alterations in glucose metabolism in patients with type 2 diabetes mellitus,” the human study concludes.

Bartges said that the study on dogs has value, but more research is needed in this area.

“It is an interesting study, but as with many studies in veterinary medicine it involved healthy animals, a small number, and a short study period,” Bartges said. “The real question that remains to be answered is what happens in animals with naturally occurring diabetes over a longer period of time. Unfortunately, this answer isnt known in humans either.”