Even though glucosamine is technically a type of sugar, it doesn’t appear to affect blood sugar levels or insulin sensitivity.

Some preliminary research had suggested that glucosamine might worsen insulin resistance, which can contribute to increases in blood sugar in people with type 2 diabetes. Dr. Andrew Weil writes, “I haven’t seen any scientific studies suggesting that people with type 2 diabetes, or anyone else, risk elevations in their blood sugar levels when they take glucosamine for the relief of arthritis pain. In fact, the one study of which I am aware found no elevations in blood glucose levels among the type 2 diabetes patients who participated. They published it in the July 14, 2003 issue of the Archives of Internal Medicine.”

Despite theoretical risks based on animal models given high intravenous doses, the combination glucosamine/chondroitin (1500 mg/1200 mg daily) does not adversely affect short-term glycemic control for patients whose diabetes is well-controlled.

References

Newell, Lori. “What Is Effect of Glucosamine on Diabetes?” Livestrong, n.d. http://www.livestrong.com/article/454296-what-is-effect-of-glucosamine-on-diabetes/ (accessed on 8/3/2020).

Weil, Andrew, MD. “Can Glucosamine Worsen Diabetes?” Weil (December 27, 2006). https://www.drweil.com/health-wellness/body-mind-spirit/diabetes/can-glucosamine-worsen-diabetes/ (accessed on 8/3/2020).
Is it safe to take glucosamine for arthritis pain if you have type 2 diabetes? Will it raise blood glucose levels?

Yu, Joseph G.; Sarah M. Boies; and Jerrold M. Olefsky. “The Effect of Oral Glucosamine Sulfate on Insulin Sensitivity in Human Subjects,” Diabetes Care 2003 Jun; 26(6): 1941-1942. https://doi.org/10.2337/diacare.26.6.1941. http://care.diabetesjournals.org/content/26/6/1941 (accessed on 8/3/2020).