Comparative effectiveness of immediate-release and extended-release metformin on gastrointestinal tolerability, quality of life, and treatment satisfaction: A prospective cohort study

Gastrointestinal (GI) side effects from metformin often limit its use and can impact patient quality of life (QoL) and satisfaction. The extended-release (XR) formulation is thought to cause fewer GI adverse events than immediate-release (IR) metformin, potentially improving tolerability, treatment satisfaction, and adherence. To compare metformin IR vs XR in terms of GI tolerability (incidence of GI side effects), patient-reported QoL, and medication satisfaction over 6 months in Saudi patients with type 2 diabetes. In a prospective cohort of 119 newly diagnosed patients with type 2 diabetes (62 on IR, 57 on XR), we tracked GI adverse events using a standardized questionnaire at baseline and 6-month follow-up. Diabetes-specific QoL was measured with the diabetes therapy-related quality of life questionnaire (DTR-QOL), and treatment satisfaction was assessed with the oral hypoglycemic agent questionnaire version 2 (OHA-Q ver. 2). Metformin XR was associated with significantly better GI tolerability. By 6 months, 45.2% of IR patients and only 24.5% of XR patients reported any GI side effect (P