Farmin Shahabuddin, MPH, National Center for Health Research
Glucosamine is one of the most popular dietary supplements sold for joint pain, especially among people with osteoarthritis. It is a substance found naturally in the body’s cartilage and often combined with chondroitin in over-the-counter pills or powders. Many people take glucosamine because they believe it will rebuild or protect joint tissue.
Dietary supplements are never approved by the U.S. Food and Drug Administration (FDA) for the treatment of osteoarthritis or any other medical condition. [1] [2] In the United States, only prescription drugs can be approved for a medical condition. In contrast, dietary supplements are not tested or regulated for effectiveness or purity before reaching store shelves. That means glucosamine products made by different companies or even made on different days can vary in terms of dosage and contamination with other substances.
The Dietary Supplement Health and Education Act (DSHEA) of 1994 allows manufacturers to market supplements without proving they are safe or effective as long as they do not make specific claims about treating or curing diseases. The FDA can only take action if a supplement is found to be adulterated or misbranded after it is on the market. [7]
What the Glucosamine Research Says About Joint Pain
The research on whether glucosamine relieves joint pain is uncertain.
- Large, well-designed studies, including the NIH-funded GAIT trial, found that glucosamine (alone or with chondroitin) was no more effective than a placebo for knee osteoarthritis. [1]
- Some smaller or European studies using a prescription-strength form of glucosamine sulfate have shown modest benefits; however, the results have been inconsistent. [3]
- Systematic reviews and medical guidelines now agree that glucosamine’s benefits are uncertain, and if there is a benefit, it is small. [1] [2]
Because of this, the American College of Rheumatology and the Arthritis Foundation recommended against using glucosamine for osteoarthritis of the knee. [1] Despite its popularity, the evidence shows that glucosamine is safe but not proven to work for most people. If it helps, the improvement is usually mild and may take several months to appear. If you want to give it a try but notice no benefit after three months, experts recommend stopping the supplement.
What are the Risks?
Although glucosamine is generally safe, there are still a few important things to know:
- Quality Varies: As a supplement, glucosamine is not regulated like prescription medicine. Some products may not contain the amount or form of glucosamine listed on the label, and some may contain other substances.
- Shellfish Allergies: Many glucosamine products are made from shellfish. People with shellfish allergies should check labels carefully. [8]
- Drug Interactions: Glucosamine may increase the effects of the blood thinner warfarin, which can increase your chances of bleeding too easily. [8]
- Other side effects: Mild stomach upset, nausea, or heartburn are occasionally reported. [8]
For these reasons, always talk to your healthcare provider before starting any supplement – especially if you take prescription medications or have chronic health conditions.
What About Diabetes Risk?
Early studies in animals and a few small human trials found that glucosamine could slightly increase insulin resistance in people who already had trouble processing glucose. [4] These early findings led to the belief that glucosamine might increase the chances of developing diabetes. However, those studies involved only a few dozen participants, lasted just a few weeks, and did not track long-term health outcomes.
New Research Shows It’s Not Risky for Diabetes
New, large studies now show that glucosamine does not increase diabetes risk—and may lower it. A 2020 study published in Diabetes Care followed more than 400,000 adults in the United Kingdom for eight years. People who regularly took glucosamine were 17% less likely to develop type 2 diabetes than people who didn’t take it. [5]
A 2025 study published in Aging Clinical and Experimental Research found similar results in over 260,000 participants, showing that glucosamine users had an 8% lower risk of developing diabetes compared to non-users. [6] Researchers believe this benefit comes from glucosamine’s anti-inflammatory effects. Inflammation plays a role in both arthritis and diabetes, and reducing inflammation can help the body use insulin more effectively.
What This Means for You
- Joint-pain relief: The evidence is mixed. Most studies show no meaningful benefit, but some people may feel mild improvement.
- Diabetes Risk: Newer, high-quality studies show no increased chances of developing diabetes and possibly a small protective effect.
- Safety: Glucosamine is generally safe when taken as directed. The most common side effects are mild stomach upset or nausea.
- If you have diabetes, it’s still wise to tell your doctor before starting any supplement, but current evidence shows no harm to blood-sugar control.
- Other proven options: Exercise, maintaining a healthy weight, and using treatments recommended by your healthcare provider are still the best ways to manage osteoarthritis symptoms.
The Bottom Line: Glucosamine is safe but unproven for joint pain. It does not help prevent diabetes, but is unlikely to harm you. If you decide to try it, talk to your healthcare provider and set realistic expectations.
All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.
- Glucosamine and Chondroitin for Osteoarthritis: What You Need to Know. National Center for Complementary and Integrative Health (NCCIH), NIH. Updated 2023. https://www.nccih.nih.gov/health/glucosamine-and-chondroitin-for-osteoarthritis-what-you-need-to-know
- National Library of Medicine. Glucosamine Sulfate. StatPearls Publishing, updated 2025. https://www.ncbi.nlm.nih.gov/books/NBK558930/
- Vo N X et al. Effectiveness and Safety of Glucosamine in Osteoarthritis. J Clin Med. 2023; 13(23): 7444. https://pmc.ncbi.nlm.nih.gov/articles/PMC10366893/
- Pham T, Cornea A, Blick KE, Jenkins A, Scofield RH. Oral glucosamine in doses used to treat osteoarthritis worsens insulin resistance. The American Journal of the Medical Sciences 2007; 333(6):333–339. doi:10.1097/MAJ.0b013e318065bdbe.
- Ma H, et al. Glucosamine Use, Inflammation, and Genetic Susceptibility, and Incidence of Type 2 Diabetes: A UK Biobank Study. Diabetes Care 2020; 43(4):719–725. doi:10.2337/dc19-2282.
- He J, et al. Regular Glucosamine Supplementation and Risk of Age-related Chronic Diseases: Evidence from a Propensity Score-Matched Cohort Study. Aging Clinical and Experimental Research 2025; 37:1–12.
- U.S. Food and Drug Administration. (2024, March 21). Dietary supplements. U.S. Department of Health and Human Services. https://www.fda.gov/food/dietary-supplements
- Berman, R. (2016, October 17). The latest on glucosamine/chondroitin supplements. Harvard Health Publishing. https://www.health.harvard.edu/blog/the-latest-on-glucosaminechondroitin-supplements-2016101710391