Gayani R. Weerasingh, MA and Brandel France de Bravo, MPH
Glucosamine is a popular dietary supplement used by many who suffer from joint pain. Most dietary supplements make claims that aren’t backed by scientific research, but NIH reports that daily doses of glucosamine can lower pain. As a result, the supplements are recommended by many physicians. However, glucosamine is a sugar that uses some glucose processing pathways. It is processed mainly through the “Hexosamine Biosynthetic Pathway,” which is involved in both glucose transport and the development of insulin resistance-the main cause of type 2 diabetes (1). Does that mean that these pills can be dangerous?
A person with diabetes does not produce enough insulin to regulate blood sugar levels in the body. Without the right amount of insulin (which is what we mean by “insulin resistance”), glucose can not be properly absorbed and used, leading to too little or too much sugar circulating in the body (1).
More research is needed to determine whether glucosamine supplements can cause diabetes in healthy adults, but meanwhile, if you are already at risk for diabetes or have diabetes, you may want to think twice before taking glucosamine. Glucosamine is already used in laboratory settings and animal studies to induce insulin resistance for the purpose of studying the condition and drugs to treat it, so clearly scientists are confident it has that effect. We also know from animal studies that glucosamine interferes with the liver’s ability to control glucose production, glucose uptake by surrounding tissue, and insulin production in pancreatic beta-cell (2).
A study of healthy men and women taking 1500mg of glucosamine a day for six weeks, published in The American Journal of the Medical Sciences, concluded that adults who already have poor insulin sensitivity will increase their risk for diabetes if they take glucosamine (2).
While some studies maintain that taking glucosamine supplements has no effect on glucose metabolism (4, 5, 6), there are reasons to be concerned. These studies’ findings could be affected by how the study was designed, how long the volunteers took glucosamine, what exactly was being measured at what times, and the family history of the study participants. For instance, the impact of glucosamine on insulin in healthy individuals of a healthy weight with no family background of diabetes is likely to be different from insulin response among overweight individuals at risk for diabetes (2). Some of the studies only measured serum glucose levels (how much sugar is present in the blood), but not insulin response, while other studies followed participants for too short a time to see insulin resistance develop.
The bottom line: glucosamine may be good for your joints but if you have a family history of diabetes or are overweight, taking glucosamine supplements could put you at greater risk for diabetes.
1) Love DC, Hanover JA. The Hexosamine Signaling Pathway: Deciphering the “O-GlcNAc Code”. Science Strike 2005; 312: 13
2) Pham T, Cornea A, Blick KE, Jenkins A and Scofield HR. Oral glucosamine in doses used to treat osteoarthritis worsens insulin resistance. The American Journal of the Medical Sciences 2007; 333(6):333-339.
3) Biggee BA, Blinn CM, Nuite M, Silbert JE, and McAlindon TE. Effects of oral glucosamine sulphate on serum glucose and insulin during an oral glucose tolerance test of subjects with osteoarthritis. Annals of the Rheumatic Diseases 2007; 66:260-262.
4) Anderson JW, Nicolosi RJ, and Borzelleca JF. Glucosamine effects in humans: a review of effects on glucose metabolism, side effects, safety consideration and efficacy. Food and Chemical Toxicology 2005; 43:187-201.
5) Albert SG, Oiknine RF, Parseghian S, Mooradian AD, Haas MJ, and McPherson T. The effect of glucosamine on serum HDL cholesterol and apolipoprotein Al levels in people with diabetes. Diabetes Care 2007; 30(11):2800-2803.
6) Scroggie DA, Albright A and Harris MD. The effect of glucosamine-chondroitin supplementation on glycosylated hemoglobin levels in patients with type 2 diabetes mellitus. Archives of Internal Medicine 2003; 163:1587-1590.