Glucosamine and glucosamine-chondroitin combinations are among the most widely used dietary supplements for improving joint health and managing osteoarthritis. A January 2011 review in “Diabetes/Metabolism Research and Reviews” estimated that glucosamine is used by 400,000 elderly diabetic patients and 2.7 million pre-diabetic individuals in the United States. Some scientific studies have raised concerns that glucosamine, but not chondroitin, raises your blood glucose level and interferes with diabetes management. However, as of 2011 flaws in these studies’ designs have prompted questions about the validity of their results.
Cartilage
The cartilage that lines and protects your joints is a tough, resilient connective tissue comprised of proteins and sugar-like molecules called glycosaminoglycans, or GAGs. These compounds are produced by specialized cells called chondrocytes that eventually become trapped within the bloodless cartilage matrix. Chondrocytes obtain their nourishment and the precursors for cartilage synthesis, including glucosamine, from fluids that are pumped through your cartilage by joint compression. Since cartilage does not contain blood vessels, it is subject to deterioration, and it heals slowly. Glucosamine and chondroitin supplements are believed to offer valuable support to this important tissue.
Hexosamines
Glucosamine is the precursor for several GAGs, including keratan and chondroitin. Your cells also use glucosamine to produce other important molecules called hexosamines, some of which have been shown to contribute to insulin resistance and diabetes. Studies in rodents have demonstrated that supplementing with glucosamine leads to increased production of undesirable hexosamines and interferes with normal glucose metabolism. Theoretically, these same changes could increase your insulin resistance and elevate your blood glucose level. However, the animal studies used to reach these conclusions employed constant intravenous infusions of glucosamine, which furnished doses far in excess of those obtained from oral supplementation.
No Effect on Glucose
In 2010, experts from Canada, the United States, New Zealand and Britain reviewed a multitude of glucosamine trials from a variety of literature sources, including studies that utilized tissue culture, various species of laboratory animals and humans as test subjects. These authors concluded that glucosamine “has no effect on fasting blood glucose levels, glucose metabolism or insulin sensitivity at any oral dose level in healthy subjects, individuals with diabetes or those with impaired glucose tolerance.”
Considerations
As with any medication or dietary supplement, the risks of glucosamine-chondroitin supplements must be weighed against their benefits before you add them to your daily routine. Available clinical evidence as of 2011 shows that neither glucosamine nor chondroitin evoke significant effects on your blood glucose level. However, large, long-term studies evaluating the effects of these compounds on glucose metabolism in specific populations have not yet been performed. If you are diabetic or glucose-intolerant, ask your doctor if glucosamine and chondroitin are appropriate for you.
References
- “Diabetes/Metabolism Research and Reviews”; A Comprehensive Review of Glucosamine Use and Effects on Glucose Metabolism in Normal and Diabetic Individuals; R.R. Simon, et al.; January 2011
- “American Journal of Physiology, Endocrinology and Metabolism”; Cross-Talk between GlcNAcylation and Phosphorylation: Roles in Insulin Resistance and Glucose Toxicity; R.J. Copeland, et al.; July 2008
