Hi Akash!
I agree with Noblehead and Sam. The human body prefers to get its fuel from carb, but in the absence of carb it simply converts some of the protein to glucose. I eat about 50g carb a day. I jab small amounts of Apidra (rapid-acting) for low-carb and no-carb meals. 1.5 units for bacon and egg for example. For a chicken salad lunch that has 5 - 8g carb in the salad, I will inject 1.5 units, but if I add 50g of orange to that raising the carb count to 12 - 15g carb, I still only need 1.5 units Apidra. Basically, less of the chicken will be converted to glucose because my body will use the glucose from the orange in preference. So in answer to your question, I would jab one or two units rapid-acting for a very low or no-carb meal, but I'd ignore the protein element in a higher carb meal. hope that makes sense.
Smidge