BACKGROUND: With increasing use of glucosamine-containing supplements for the treatment of osteoarthritis, there is increasing concern in the medical community about possible toxic effects. The present study was undertaken to determine whether glucosamine supplementation altered hemoglobin A1c concentrations in patients with well-controlled diabetes mellitus. OBJECTIVE: To evaluate possible effects of glucosamine supplementation on glycemic control in a selected population of patients with type 2 diabetes mellitus. DESIGN: Placebo-controlled, double-blinded, randomized clinical trial. SETTING: Outpatient, diabetes monitoring clinic. PATIENTS: Patients were typically elderly patients, evenly divided between men and women. Most of the patients were being treated with 1 or 2 drugs for glycemic control. INTERVENTION: In daily doses for 90 days, patients received either placebo or a combination of 1500 mg of glucosamine hydrochloride with 1200 mg of chondroitin sulfate (Cosamin DS; Nutramax Laboratories Inc, Edgewood, Md).Main Outcome Measure Hemoglobin A1c levels before and after 90 days of therapy. RESULTS: There were 4 withdrawals from the glucosamine-treated group. Three were related to comorbidities (myocardial infarction, congestive heart failure, and atrial fibrillation) and 1 to a possible adverse reaction (excessive flatus). No other patient reported any adverse effects of glucosamine therapy, and no patient had any change in their diabetes management. Mean hemoglobin A1c concentrations were not significantly different between groups prior to glucosamine therapy. Posttreatment hemoglobin A1c concentrations were not significantly different between groups, nor were there any significant differences within groups before and after treatment. CONCLUSION: This study demonstrates that oral glucosamine supplementation does not result in clinically significant alterations in glucose metabolism in patients with type 2 diabetes mellitus. Scroggie DA, Albright A, Harris MD. Arch Intern Med. 2003 Jul 14;163(13):1587-90.