[More information on glucosamine and chondroitin is available from the American Academy of Orthopaedic Surgeons]
Should diabetics use glucosamine? Until further information is known, diabetics should only take glucosamine under the supervision of their doctors. Discuss possible side effects (eg. digestive upset, headaches, drowiness) as well as the possibility that your blood sugar levels may increase. Regular monitoring of your blood glucose levels and your hemoglobin A1C, typically every 3 months, should be done to ensure the glucosamine isn't affecting you adversely.
If you decide to include glucosamine as part of your therapy, more frequent monitoring of blood glucose levels can show you how your body is reacting. Any pattern of change in blood sugar should be reported to your doctor so that you can discuss whether to continue taking the supplements.