There appear to be no problems in people with diabetes, obesity or heart diseases after taking glucosamine sulfate (average 1,500 milligrams daily for up to three years). There are no changes in blood glucose or cholesterol levels. Human studies gave 5000 mg of glucosamine intravenously, and found no alterations in blood glucose or its metabolism. These results, when combined, show that oral doses of glucosamine have no risk for harm.