I KNOW OF SOMETHING THAT WORKS!! Of course, my lowering the insulin in your system, and losing weight you can affect the acanthosis nigricans. However, this is a topical medication that has helped me! The name of the medication is Tri-luma. Although it is normally prescribed for melasma is does work on acanthosis nigricans. I just started using it less than 2 weeks ago and there are areas of my neck that actually look like my normal skin! The only bad part is that in the beginning i tried just testing 2 spots and now there are 2 spots on my neck that look completely normal in the middle of all of the dark skin so be careful about that. It does have some side effects as it does sometimes cause itching and because it has tretinion in it you have to be careful not to make your skin raw. THe medicine is a combination of a skin lightner, tretinoin and i think a cortisode cream. In anycase, it seems to be working for me. I have just received my first prescription for glucophage and I am hoping that helps even more. I just happened to come across the site and wanted to share this with you all. I wish the best of luck to you all!