Having to snack when you inject sounds very wrong to me, it should be the other way round! You shouldn't have to feed your insulin with carbs, rather you should feed your carbs with insulin. Are you on MDI? If not then maybe you should be, if you are then it needs sorting out. Do you carb count? Ie take the appropriate amount of insulin for you depending on what you are eating? It sounds daunting at first but actually is not that bad when you get the hang of it plus there are courses such as DAFNE that can help. It sounds like you need a diabetes overhaul!