Is your pancreas broken?
Insulin CAN be very effective at adding size. Insulin also CAN be very effective at making you fat. The key is how you take it.. ie, at certain times like PWO where your body can utilize it better. Lantus takes away this advantage. Also, to actually get a "bodybuilding" advantage from it, you have to take a lot.. which can be dangerous. So it is not any safer than any other form of slin.
Start taking a GDA supplement, there are many out there. Start with taking it 2 times per day, with breakfast, and then with your post workout meal. Ideally you take it with breakfast to get the day started, and then with your post workout meal, because ideally that should be your biggest.