GLUCOSAMINE FOR OSTEOARTHRITIS: PART II, BIOLOGIC AND METABOLIC CONTROVERSIES

Medicine and Health Rhode Island,  Jun 2004  by Biggee, Beth Anne,  McAlindon, Timothy

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Glucose and glucosamine are competitors in the liver for carbohydrate metabolism. Cell culture and animal studies show that glucosamine interferes with glucose transport and insulin secretion leading to hyperglycemia and insulin resistance.16,17,18 Oral glucosamine's effect on insulin resistance in animals and humans has been conflicting.19, 20, 21, 22, 23, 24 Despite this, there is speculation that glucosamine could predispose to diabetes. In fact, the Arthritis Foundation recommends that patients with diabetes monitor blood glucose levels more frequently while taking glucosamine. 25 This is important because diabetes mellitus affects up to 12% in people aged 60-74 years old, the same age group at risk for osteoarthritis.26,27 On the other hand, studies suggest that glucosamine sulfate is extensively metabolized by the gastrointestinal system in humans.3 Most of these metabolic studies were performed with glucosamine infusions, which bypass important steps of competitive metabolism in the liver. These intravenous methods are non-physiologic and may not be generalizable to populations who take oral ingestions of glucosamine. 28

One recent study evaluated the effects of glucosamine-chondroitin on glycosylated hemoglobin levels in patients with Type 2 Diabetes Mellitus diet controlled or those taking stable oral antihyperglycemic medications.29 Thirty-eight subjects were randomized in a double-blind, placebo-controlled trial to determine the effect of treatment with glucosamine hydrochloride-chondroitin on HbA1C levels in diabetics after 90 days of therapy. All subjects were instructed to monitor daily finger-stick glucose levels. Subjects were instructed to report any changes to clinic personnel. They were to return their daily blood sugar log at the end of study and were to report any changes in medication especially antihyperglycemics. The study reported no changes in medical therapy in either group. Importantly, however, the study did not report on finger stick logs in either group and did not report on any diet modifications during the study.

This study found no significant increase in HbA1C levels after 90 days. Subjects in the glucosamine group did have an increase of HbA1C level from 6.45% to 6.50%, although not significant, whereas those in placebo group actually had a decline in HbA1C level of 6.25% to 6.09%, not significant. It may be likely that all study patients were more compliant with diabetic medications and diet control while on study protocol accounting for decrease in HbA1C in placebo group. This decrease was not observed for the glucosamine group. This may indicate that despite strict adherence to medical treatment and diet control, glucosamine ingestion may trend toward hyperglycemie states.

SUMMARY

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.