Sodium-Glucose Co-transporter 2 Inhibitors Versus Metformin as the First-Line Treatment for Type 2 Diabetes: Is It Time for a Revolution?

Sodium-glucose co-transporter 2 inhibitors (SGLT2i) have emerged as a promising therapeutic option for hyperglycemia and its complications. However, metformin remains the first-line pharmacological treatment in most algorithms for type 2 diabetes (T2D). Although metformin is generally believed to exert positive effects on cardiovascular (CV) outcomes, relevant data are mainly observational and potentially overinterpreted. Yet, it exerts numerous pleiotropic actions that favorably affect metabolism and diabetes comorbidities. CV outcome trials have demonstrated cardiorenal protection with SGLT2i among people at high CV risk and mostly on concomitant metformin therapy. However, post hoc analyses of these trials suggest that the cardiorenal effects of gliflozins are independent of background treatment and consistent across the full spectrum of CV risk. Considering the importance of addressing hyperglycemia as a means of preventing diabetic complications and significant knowledge gaps, particularly regarding the cost-effectiveness of SGLT2i in drug-naive populations with T2D, the position of metformin in the management of people with diabetes at low CV risk remains solid for the moment. On the other hand, available evidence-despite its limitations-suggests that specific groups of people with T2D, particularly those with heart failure and kidney disease, could probably benefit more from treatment with SGLT2i. This narrative mini-review aims to discuss whether current evidence justifies the use of SGLT2i as the first-line treatment for T2D.