<p>The most often given first-line treatment for type 2 diabetic mellitus (T2DM) is metformin because of its shown effectiveness, cost-efficiency, and safety record. Originally recognized for its ability to lower blood sugar levels by inhibiting hepatic gluconeogenesis, more recent studies have uncovered a complex web of activities that includes AMP-activated protein kinase (AMPK) activation, mitochondrial function modulation, and AMPK-independent pathways like lysosomal signaling, redox regulation, and gut microbiota interaction. Metformin has been shown to provide protective benefits on the heart and maybe the kidneys, maintain weight neutrality or mild loss, and lower A1C levels by 1% to 1.5%. It is appropriate for a variety of demographics, including the elderly and people with early-stage chronic renal disease, because it is well tolerated and linked to a minimal risk of hypoglycemia. Its promise in non-diabetic conditions such obesity, cancer, neurological diseases, aging-related decline, and polycystic ovarian syndrome (PCOS) has also been investigated in recent studies. Recent data points to a function in regulating immunological responses and systemic inflammation, with potential uses in infectious disorders such as COVID-19. Additionally, the creation of combination medicines (e.g., with SGLT2 inhibitors and GLP-1 receptor agonists), extended-release formulations, and enhanced delivery systems have been made possible by new patents and pharmacological advancements. This review incorporates the most recent research and patent developments, assesses the drug’s changing clinical value, and integrates our current understanding of metformin’s complex mechanisms. As the field of managing metabolic diseases develops, metformin continues to be a cornerstone treatment and a viable option for precision medicine and repurposing in a variety of chronic and new conditions.&#xa0;</p> Graphical Abstract <p></p>