I need help with my diabetes type 1 and my psoriasis!!!!!!?

Ok my father has type 1 diabetes and psoriasis very badly on his back, head, and underarms. He was taking some kind of diabetic Medication called Avandia 8mg., we believe thats what it was called. He has switched doctors and the one he has now wont prescribe him that medication because it is not yet proven to help with psoriasis. But I have took it before and it made my psoriasis go away pretty much completly. Do you know of any kind of medication that is proven to work for severe psoriasis. I would prefer a site that has Avandia for a decent price. Also has anyone else tried this medication or know anyone that has, if so what was the results/side affects. Serious answers only please!
Also if possible do you know of a site that takes medicaid insurance located in Bristol Virginia for Avandia or any other medication that is proven to cure psoriasis.

I had a rash over my knees, elbows and ankle bones that the doctor said was psoraisis. It did not respond to psoraisis medications that were prescribed. It did go away completely when my blood sugar control improved. I did not take Avandia though. I was prescribed Novolog and Lantus insulins for my diabetes. Perhaps it was just the fact that improved blood sugar control helped the rash resolve.