Long-term effects of adding an SGLT-2 inhibitor to insulin therapy in patients with type 1 diabetes. An observational study and systematic review of real-world evidence

Purpose: The addition of SGLT2i to insulin therapy in type 1 diabetes (T1D) is an emerging treatment strategy. This study evaluates the real-world effects of SGLT2i on glycaemic control and other outcomes in individuals with T1D. Methods: In this single-center retrospective study, we included 78 adults with T1D who initiated SGLT2i and were observed for up to 24 months. Data included demographics, laboratory values, diabetic complications, and ongoing therapy. The primary outcome was the change in HbA1c over time. Persistence on therapy and adverse events were also recorded. Results: The mean age was 47.2 years, diabetes duration 24.6 years, baseline HbA1c 8.3%, and BMI 29.8 kg/m2. The median persistence on therapy was 14.8 months. HbA1c reduction was significantly associated with persistence (p = 0.01), with a maximum decrease of 0.61% at 6 months (p < 0.001). Time in range improved by 13.7% at 3 months (p < 0.001). Persistent users experienced a maximum weight loss of 2.5 kg at 9 months (p < 0.001). Insulin doses declined significantly (max 15% at 21 months). UACR declined significantly at 15 months (p = 0.025). Treatment discontinuation due to adverse events (mainly genitourinary tract infections) occurred in 25.6% of patients, and 1 episode of diabetic ketoacidosis was recorded. A review of the literature suggests that the observed effects are within the range of benefits reported previously from different countries. Conclusion: SGLT2i addition to insulin therapy in T1D patients resulted in sustained HbA1c reductions and weight loss. Therapy persistence significantly influenced outcomes, underscoring the importance of patient selection and monitoring for adverse effects.