A more accurate method of determining an Insulin to Carbohydrate Ratio for an individual diabetic is provided. The individual, who has been using or has been given a prior suggested dosage of rapid-acting insulin to be taken prior to meals, first plans a benchmark meal ("the Meal") and precisely counts the number of grams of carbohydrates which will be consumed in the meal. The individual blood glucose level is measured before the meal, then the previous dosage of rapid- acting insulin is injected. After the meal another reading is taken of the individual's blood sugar level. The number of units X of carbohydrates for each unit of rapid-acting insulin to be taken before future meal is then calculated by a unique formula.