T1DM patients usually determine their bolus insulin requirements using a patient and daytime specific carbohydrate to insulin ratio (CIR)and insulin sensitivity factor (ISF). In standard bolus calculators only the carbohydrate content of the meal is used, whereas newer research suggests that also fat and protein should be considered. Especially meals with a high fat content are reported to require additional insulin. However, it remains disputed how to account for mixed meal composition appropriately when calculating bolus insulin needs.