I don't know of any Dr that would advise insulin for a nondiabetic patient, even the most liberal minded. Insulin will work to increase nutrient storage in fat and muscle but it would be best used by a very advanced bodybuilder, that has exhusted cycing on steroids alone. At that point, I would suggest putting together a protocol of test/gh/insulin with proper nutrient timing.   It doesn't sound like you are at that point. There are 2 reasons that I'm not suggesting insulin. 1, it can make most people gain more fat than gain muscle, especially without GH and 2, it can kill you. Death or coma can be avoided with proper nutrient timing, but unless you are advanced, there are a lot safer options. I would suggest you look into some safer peptides. GH or IGF-LR3 comes to mind. IGF works well for increasing pumps, which are always welcomed when off of gear. As the name states, it is "insulin-like". It'll increase nutrient storage and help with new growth, while not effecting your HPTA. 

30-40mcg, taken right before your workout, on training days only would be a good place to start. I would run that dose for 6-8 wks on, 3-4 wks off. There is no need for any kind of PCT with IGF-LR3. You can run it on cycle, off cycle, or in PCT.