Renal and Glycemic Outcomes with Linagliptin versus Vildagliptin as Add-On Therapy in Uncontrolled Type 2 Diabetes Mellitus: A Prospective Observational Study

Abstract

Background: Linagliptin and vildagliptin are commonly used dipeptidyl peptidase-4 (DPP-4) inhibitors, but direct real-world comparisons of renal and glycemic outcomes remain limited. This study compared the renal profile, glycemic response, and tolerability of these agents in adults with uncontrolled type 2 diabetes mellitus (T2DM). Methods: In this prospective observational cohort study, 100 adults with T2DM inadequately controlled on stable metformin monotherapy were allocated to linagliptin 5 mg once daily (n=50) or vildagliptin 50 mg twice daily (n=50), each added to metformin 500 mg twice daily. Clinical, glycemic, renal, hematological, lipid, hepatic, and adverse-event data were assessed at baseline, 2 months, and 6 months. Results: Baseline characteristics were comparable between groups. At 6 months, fasting plasma glucose was 105.42±12.52 mg/dL with linagliptin and 108.10±10.23 mg/dL with vildagliptin (between-group p=0.472); postprandial glucose was 151.25±10.25 versus 152.32±12.32 mg/dL (p=0.289); and HbA1c was 6.01±0.21% versus 6.12±0.41% (p=0.396). Renal indices also remained similar at 6 months, including serum creatinine (0.89±0.38 versus 0.89±0.79 mg/dL; p=0.685) and estimated glomerular filtration rate (81.23±9.45 versus 81.36±10.23 mL/min/1.73 m²; p=0.814). Adverse events were mild and did not differ significantly between treatments. Conclusions: Linagliptin and vildagliptin produced comparable short-term glycemic improvement when added to metformin, with broadly stable renal indices and similar tolerability over 6 months. Larger controlled studies with longer follow-up are needed to define their comparative long-term renal safety.

Keywords: diabetes mellitus, type 2; dipeptidyl peptidase-4 inhibitors; linagliptin; vildagliptin; metformin; renal function; estimated glomerular filtration rate; glycated hemoglobin