Patterns and Clinical Outcomes of Sitagliptin/Metformin Extended-Release in Internal Medicine: A Real-World Multicenter Italian Study

Background: In internal medicine, the management of type 2 diabetes mellitus (T2DM) is challenged by multimorbidity and polypharmacy. The fixed-dose combination of sitagliptin and extended-release metformin (SITA/MET ER) is a valuable option for frail and comorbid patients. Methods: This multicenter, retrospective, observational study involved five Italian Internal Medicine units. Consecutive patients with T2DM who initiated SITA/MET ER were included. Demographic, clinical, and laboratory data were collected at baseline (T0) and at follow-up (T1, 3–4 months). The primary endpoint was change in HbA1c; secondary endpoints included fasting plasma glucose (FPG), treatment adherence, adverse events, and modifications in concomitant antidiabetic therapies. Results: A total of 292 patients (mean age 70.8 ± 10.6 years; 43% female) were analyzed. At baseline, mean HbA1c was 7.4 ± 1.0% and FPG 150.2 ± 42.5 mg/dL, with significant reductions observed at follow-up (HbA1c 7.0 ± 0.8%, FPG 136.8 ± 29.6 mg/dL; both p < 0.05). SITA/MET ER was predominantly prescribed to patients with a complex clinical profile, as reflected by the high prevalence of microvascular (37%) and macrovascular (42%) complications. The use of sulfonylureas decreased from 11% to 3% (p < 0.001), while SGLT2 inhibitor and insulin use remained stable. Treatment adherence to SITA/MET ER was excellent, with full compliance reported and no adverse events recorded. Conclusions: In this real-world internal medicine study, SITA/MET ER improved glycemic control and was well tolerated among patients with complex clinical profiles. These findings support the role of SITA/MET ER as a flexible and practical therapeutic choice in this setting.