if i go to the gym on a regular basis and avoid fast food and potatoes how much insulin should i be injecting per day?

This is a very difficult question to answer and the answer will change over time. Going to the gym on a regular basis and eating well are essential to overall diabetes care but neither of these tell you how much insulin you need to keep glucose levels under control. Your weight and A1C levels will be a good starting point for your physician to determine where you need to be. Remember, when sugar levels are elevated you will require more insulin. Exercise and healthy eating will lower the amount of insulin needed. It also depends on which type of diabetic you are...a type 1 generally requires less insulin than a type 2 because type 2 diabetics are usually somewhat insulin resistent. (Meaning the insulin you make or inject is not working without larger doses being administered.) Type 1 diabetics, remember, never get off of insulin. Type 2 diabetics can get off of insulin and be treated with only pills and exercise if conditions warrant it. I hope this helps. Unfortunately, insulin dosages are somewhat trial and error until the proper amounts are found. Hope this helps!!