The RD, physician, or diabetes educator determines how much rapidacting insulin the child needs to cover carbs (insulin-to-carb ratio) and how much rapid-acting insulin is needed to lower blood glucose to target range (blood glucose correction factor). Insulin- to-carb ratios vary from child to child. For example, a 5-year-old may use an insulin-to-carb ratio of 1 unit per 30 to 45 grams of carb, while teenagers may use 1 unit for 7 to 15 grams of carb.
NPH starts working midmorning and peaks in the afternoon, balancing with the carbs at morning snack, lunch, and afternoon snack. Carb amounts at those times need to stay consistent to help keep blood glucose within the target range. Snacks for most school-age children are 15–30 gm carb.