Analysis of Side Effects of Metformin in Patients with Type 2 Diabetes Mellitus

Objective: To determine the frequency of side effects among various metformin formulations and to examine their association with the method of drug administration, the type of therapy prescriber, and patient education level.Participants and Methods: The study included 126 patients with type 2 diabetes mellitus, who were assessed using a specifically structured questionnaire. The survey was conducted at the outpatient clinic of the Regional Center for Endocrinology, Diabetology and Metabolic Disorders, University Hospital Centre Split.Results: Adverse effects caused a change in therapy in 15.4% of patients. A statistically significant decrease in adverse effects was observed when comparing the initial and current treatment ( p = 0.004 ). Monotherapy with metformin preparations, whether Immediate Release ( IR ) or Extended Release ( ER ), significantly more frequently caused adverse effects compared to comb preparations of metformin and other drugs ( SGLT2 inhibitors, DPP-4 inhibitors ) ( p = 0.007 ). Depending on meal timing, 63.2% of patients took the medication correctly, while 27.2% took it incorrectly. Adverse effects occurred in 10.13% of patients who took the medication correctly, and in 15.22% of those who took it incorrectly. Specialists prescribed therapy for 89.6% of patients, while family medicine physicians prescribed therapy for 10.4%. Regarding patient education about medication intake related to meals, adverse effects were reported in 25% of poorly informed patients, while the adverse effects decreased from 25.4% to 11.47% in better informed patients.Conclusion: Metformin preparations differ in the frequency of adverse effects, with monotherapy metformin preparations, whether Immediate Release ( IR ) or Extended Release ( ER ), more frequently causing adverse effects compared to comb-preparations of the same drug. No statistically significant difference was found in the occurrence of adverse effects depending on the prescribing physician. There is no statistically significant frequency of adverse effects among patients who were poorly informed about medication intake concerning meals, nor is there a statistically significant difference in adverse effects associated with inadequate therapy intake concerning meals.