It all depends on how well your buddy manages his diabetes. I am a type I diabetic, I keep my sugars well under control. My sugar counts very rarely get high and my sugar average is always in the normal range. I am about to start my 4th cycle in a few months.. I just choose not to do orals or any "hardcore" roid, just simple test cycles. Now I take insulin, most type II diabetics take oral meds. So your buddy may want to check if taking steroids, AI's or PCT will effect his medication.