Can DPP-4 Inhibitors Improve Glycemic Control and Preserve Beta-Cell Function in Type 1 Diabetes Mellitus? A Systematic Review

<b>Background/Objectives</b>: The objective was to analyze the effects of Dipeptidyl Peptidase-4 (DPP-4) inhibitors on glycemic control, insulin dose, and preservation of β-pancreatic function (C-peptide) in patients with type 1 diabetes mellitus (T1DM). <b>Methods</b>: A systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with a search in the PubMed database. Five randomized clinical trials evaluating the use of different DPP-4 inhibitors in patients with T1DM were selected, measuring parameters including glycated hemoglobin (HbA1c), C-peptide, time in glycemic target/range (TIR), and daily insulin dose. <b>Results</b>: HbA1c showed significant reduction in some studies and no significant alterations in others. TIR increased in one study (~77.87% → ~84.40%). C-peptide showed variable effects across studies. The insulin dose did not show a substantial reduction. <b>Conclusions</b>: DPP-4 inhibitors demonstrated modest benefits for glycemic control and preservation of β-cell function in T1DM, but these effects were inconsistent due to methodological heterogeneity. Standardized studies are needed to define beneficial subgroups and long-term efficacy.