After 4 weeks of treatment with glucosamine sulfate, there was no change in the area under the 4-h plasma glucose curve (AUCgluc) (1,551 ± 55 vs. 1,539 ± 55 mmol · l−1 · min−1) and the 4-h MTT plasma insulin curve (AUCins) (17,903 ± 8,745 vs. 17,861 ± 9,406 mU/l · min) in all subjects.
Insulin sensitivity was significantly reduced at baseline in the obese compared with the lean subjects (lean: 3.58 ± 0.6; obese: 1.2 ± 0.4 × 10−4 min−1 · μU−1 · ml−1; P < 0.01). After 4 weeks of treatment with glucosamine, there was no difference in insulin sensitivity in the combined group of subjects (2.37 ± 0.46 vs. 2.55 ± 0.58; P = 0.67), nor was there any difference when the subjects were analyzed according to BMI (obese or lean) or glucose tolerance (normal glucose tolerant or IGT).
Although there are many studies showing that acute or chronic administration of glucosamine and activation of the hexosamine pathway can cause insulin resistance, few studies on humans exist. Monauni et al. (2) reported that acute, short-term (6-h) intravenous glucosamine infusion had no detectable effects on glucose metabolism during a euglycemic clamp. Similarly, Pouwels et al. (3) reported that a 5-h infusion of glucosamine did not affect whole-body glucose uptake in human subjects. To date, there have been no studies on the chronic effects of oral glucosamine on insulin sensitivity.
