Background: Ramadan Iftar meal typically causes glucose excursions. Dipeptidyl peptidase-4 inhibitors increase serum concentrations of glucagon-like peptide-1 and thus, decrease blood glucose levels with low risk of hypoglycemia.

Aim: To investigate the efficacy and safety of vildagliptin as an add-on therapy among adolescents and young adults with type 1 diabetes mellitus (T1DM) on glucose excursions of Iftar Ramadan meals and glycemic metrics during advanced hybrid closed-loop (AHCL) treatment.

Current management of people with type 1 diabetes mellitus (T1DM) on intensive insulin therapy recognizes carbohydrates as the most important determinant of postprandial glycaemia; hence, worldwide guidelines recommend carbohydrates counting for determining pre-prandial insulin doses. Currently, the insulin to carbohydrate ratio (ICR) is frequently used to calculate the meal insulin dose. However, ICRs are considered difficult, ineffective and inaccurate for some patient, with an estimation error of around 20% in adults demonstrating only modest improvements in glycated hemoglobin (HbA1c). This lack of effectiveness and the wide variability using ICRs suggests it should be improved upon.

However, there have been only a few randomized control studies that investigated the efficacy and safety of DPP-4 inhibitors as an add-on drug in patients treated with basal insulin. Therefore, we conducted a one-month randomized control trial to investigate the efficacy and safety of DPP-4 inhibitors as an add-on therapy among adolescents and young adults with T1DM on glucose excursions of Iftar Ramadan meals and glucometrics during AHCL treatment .

Inclusion Criteria:

• patients with type 1 diabetes (T1DM )for at least one year
• patients aged 12-27 years
• patients using MiniMed 780G AHCL system (Medtronic, Northridge, CA, USA) at least 6 months before the study
• patients with minimum daily insulin requirement of more than 8 units
• patients willingness and ability to adhere to the study protocol, access to the internet and a computer system that met requirements for uploading the study pump data.

Exclusion Criteria:

• patients with any microvascular or macrovascular complications
• pregnancy, lactation
• patients who had a point-of-care screening HbA1c >10.0% (86 mmol/mol)
• patients with hypoglycemic unawareness or recurrent severe hypoglycemic episode in the last 6 months prior to recruitment
• patients with recurrent DKA (more than 2 episodes in the previous 6 months).
• patients with any chronic medical condition, current use of medications (other than insulin) that are known to affect blood glucose level.
• patients who had prior adverse reactions to the adjunctive agent