To illustrate calculation of a lunchtime dose, assume the following: Preprandial fingerstick glucose: 240 mg / dL (13.3 mmol / L) Total daily dose of insulin: 30 units basal insulin + 10 units bolus insulin per meal = 60 units total, daily Correction factor (insulin sensitivity factor): 1800/60 = 30 mg / dL / unit (1.7 mEq / L / unit, or 1.7 mmol / L) Estimated carbohydrate content of upcoming meal: 50 g Carbohydrate: insulin ratio (CIR): 500/60 = 8: 1 Target glucose: 120 mg / dL (6.7 mmol / L) Prandial insulin dose = 50 g carbohydrate divided by 8 g / unit insulin = 6 units Correction dose = (240 mg / dL - 120 mg / dL) / 30 correction factor = 4 units ([13.3 mmol / L - 6.7 mmol / L] / 1.7 = 4) Total dose prior to this meal = prandial dose + correction dose = 6 + 4 = 10 units rapid-acting insulin Such physiologic regimens allow greater freedom of lifestyle because patients can skip or time-shift meals and maintain normoglycemia.