Oral Glucosamine Impact on Insulin Sensitivity and Capillary Recruitment in Normal and Obese Individuals

This study explores the effects of Glucosamine, a popular nutritional supplement used for treating osteoarthritis, on insulin sensitivity and capillary recruitment in both normal and obese individuals. While intravenous glucosamine has been found to cause insulin resistance and vascular endothelial dysfunction, the potential effects of oral glucosamine on these factors remain unexplored. This research is crucial as insulin resistance and vascular dysfunction contribute significantly to major public health issues like diabetes, obesity, hypertension, and cardiovascular diseases. The study involves normal healthy volunteers and obese insulin-resistant subjects. Participants will take part in a randomized double-blind, placebo-controlled, crossover study. They will receive either a placebo or oral glucosamine (500 mg three times a day for 6 weeks). The study will use the reference standard hyperinsulinemic isoglycemic glucose clamp technique to evaluate insulin sensitivity before treatment, after placebo or glucosamine, and after the crossover. Insulin-stimulated capillary recruitment will also be assessed using the ultrasound microbubble contrast technique. This will help measure blood flow in the brachial artery and capillary recruitment in forearm skeletal muscle in response to hyperinsulinemia. Additionally, plasma glucosamine levels will be measured before each glucose clamp study. The study aims to determine if oral glucosamine worsens insulin resistance and capillary recruitment in obese subjects or causes significant insulin resistance in healthy volunteers.