Sodium-glucose co-transporter-2 (SGLT2) inhibitors have several beneficial effects in patients with type 2 diabetes, including glucose lowering, weight loss, blood pressure lowering, and a reduced risk of major adverse cardiovascular events. To address high unmet medical need via improved glycaemic control, several clinical trials have been done to assess the efficacy and safety of SGLT2 inhibitors in combination with insulin therapy in patients with type 1 diabetes. In this Personal View, we summarise data from eight clinical trials of canagliflozin, dapagliflozin, empagliflozin, and sotagliflozin in patients with type 1 diabetes. HbA-lowering efficacy was greatest at 8-12 weeks of therapy, but the magnitude of HbA lowering waned with longer duration of treatment (up to 52 weeks). Data are not yet available to establish for how long glycaemic efficacy could be sustained during long-term therapy in patients with type 1 diabetes. Moreover, SGLT2 inhibitor therapy induces serious adverse events, including a roughly six-times increased risk of diabetic ketoacidosis. The US Food and Drug Administration estimated that one additional case of ketoacidosis will occur for every 26 patient-years of exposure of patients with type 1 diabetes to sotagliflozin therapy. Assuming a case mortality of 0·4%, this estimate translates into 16 additional deaths per year per 100 000 patients with type 1 diabetes undergoing treatment. These considerations raise important questions about the risk-to-benefit profile of SGLT2 inhibitors when used as adjunctive therapy in patients with type 1 diabetes.