Baseline Profile and Adverse Drug Reaction Pattern of Dipeptidyl Peptidase-4 Inhibitors in Patients with Type 2 Diabetes Mellitus: A 12-Month Prospective Observational Study from a Tertiary Care Teaching Hospital in Kalaburagi

Abstract

Background: Dipeptidyl peptidase-4 (DPP-4) inhibitors are established oral glucose-lowering agents used in the management of type 2 diabetes mellitus (T2DM). Although their safety has been extensively evaluated in randomized clinical trials, prospective real-world data describing the spectrum and severity of adverse drug reactions (ADRs) among individual DPP-4 inhibitors remain limited in routine-care settings in India. Objectives: To describe the baseline demographic characteristics of patients with T2DM receiving DPP-4 inhibitors and to document the frequency, spectrum and severity of reported ADRs during 12 months of routine clinical follow-up, including an agent-wise description of sitagliptin, vildagliptin, linagliptin and saxagliptin. Methods; A prospective, non-randomized observational cohort study was conducted in the Department of General Medicine, Basaveshwar Teaching and General Hospital, Kalaburagi, from June 2025 to July 2026. Adults aged ≥35 years with T2DM and baseline HbA1c >6.5% who were receiving physician-prescribed DPP-4 inhibitor therapy were followed at baseline and at 3, 6, 9 and 12 months. The complete-case DPP-4 cohort comprised 250 participants. Data were analysed using IBM SPSS Statistics version 32.0 and summarized using frequencies, percentages and mean ± standard deviation. Results: Among 250 participants, 128 (51.2%) were male and 122 (48.8%) were female. The mean age was 56.62 ± 6.23 years, with 119 (47.6%) participants belonging to the 56–65-year age group. Reported ADRs occurred in 38 participants (15.2%), whereas 212 (84.8%) had no recorded ADR. Of the 38 participants with ADRs, 31 (12.4% of the total cohort) experienced mild reactions and 7 (2.8%) experienced moderate reactions; no severe reaction was recorded. The largest number of recorded ADR cases occurred among participants receiving saxagliptin (12; 4.8%), followed by sitagliptin (10; 4.0%), vildagliptin (9; 3.6%) and linagliptin (7; 2.8%). Headache was the most frequently recorded reaction (11; 4.4%), followed by upper respiratory tract infection (7; 2.8%). Four cases of hypoglycaemia (1.6%) were recorded, all among participants receiving saxagliptin. Conclusion: In this single-centre prospective observational cohort, reported ADRs among patients receiving DPP-4 inhibitors occurred in 15.2% of participants and were predominantly mild, with no severe reactions recorded. Headache and upper respiratory tract infection were the most frequently documented reactions. Drug -wise counts showed the greatest number of recorded ADR cases among saxagliptin users; however, these descriptive frequencies should not be interpreted as comparative drug-specific risk because individual-agent denominators and formal comparative analyses were not available. Continued pharmacovigilance and larger multicentre studies with standardized ADR ascertainment and formal causality assessment are warranted.