Why does Glucosamine and Chrondritin not to be taken if you are overweight?

I am overweight and have taken Glucosamine Sulfate (only one based on studies proven to work) and Chondroitan with no weight gain... I have actually lost 40 pounds while on it with no problem. My dad is an insulin diabetic and has taken it longer than I. He has not noticed change in his blood sugar, although he has been on Alpha lipoic acid and acteyl choline that helps his blood sugar. He has had no weight gain, and recently is working on losing weight. He has lost 15 pounds. I have had 4 spinal fusions, and my dad has a horrifically arthritic knee, and it has helped us so much, that the positives would far outweigh any claim of weigh gain or causing of diabetes. If I get diabetes, it is because of my poor diet and lack of exercise. I am of course finally doing something about that, so I do not end up like my dad, or my grandfather who lost part of leg due to diabetes. Also, since I haven't written enough :) let me just add it may be due to all the additives and sugars added to sooo many vitamins. I checked my bottle for Andrew Lessman ( can get at HSN or Procaps Labs) and he has absolutely NO addtives. I love his vitamins... worth every penny... and trust him and his product... and I cannot say that about most of the companies nowadays. Check it out! He has incredible reviews for a reason!

Some studies show it can aggravate insulin resistance which many who are overweight have. I would just run it past your PCP to be sure he thinks it is okay for you to try. Some evidence shows it helps (glucosamine sulfate form only) and other evidence shows it is no better than placebo so the jury is still out to the benefits of this combination. Some studies have shown glucosamine can destroy pancreatic cells which may lead to diabetes (which by being overweight, you are already risking development of diabetes)