Background: Postprandial hyperglycemia (PPH) is common clinical problem among patients with type 1 diabetes (T1D), especially in relation to high glycemic index (h-GI) meals. The main problem are high, sharp glycemic spikes with following hypoglycemia after h-GI meal consumption. There is lack of effective and satisfactory solutions concerning insulin dose adjustment to cover the h-GI meal. The goal of this research is to find out whether a Super Bolus is an effective strategy to prevent postprandial hyperglycemia and late hypoglycemia after h-GI meal in comparison to the normal bolus.Methods: A total of 72 children aged 10-18 years with T1D for at least 1 year, treated with continuous subcutaneous insulin infusion for more than 3 months will be enrolled in a double-blind, randomized, cross-over clinical trial. Participants will receive the prandial insulin bolus for h-GI breakfast in the form of Super Bolus and as Normal Bolus another day. The primary outcome measure will be the glucose level 90 minutes after administration the prandial bolus. The secondary endpoints will refer to glucose level 30, 60, 120, 150, 180 minutes postprandially; the area under the blood glucose curve within 180 min postprandially; the peak glucose and time to peak glucose level; the glycemic rise, mean amplitude of glycemic excursion, time in postprandial glucose range and the number of hypoglycemia episodes.Discussion: There is a lack of clinical studies concerning this kind of bolus. Available literature refers only to in-silico studies and case reports. The Super Bolus was defined as a prandial insulin dose increased by 50% in comparison to the dose calculated based on individualized patient’s Insulin-Carbohydrate Ratio (ICR) and simultaneous suspension of the basal insulin for 2 hours. The comprehensive and effective solution to this frequent clinical difficulty of PPH after h-GI meals has not been found yet. The problem is known and important but the presented solution innovatory and easy to apply in every-day life.Trial registration: The trial was registered at the ClinicalTrials.gov prior to the inclusion of the first patient, 15 July 2019 on registration number: NCT04019821.