Effect of switching from intermittently scanned to real-time continuous glucose monitoring in adults with type 1 diabetes: 24-month results from the randomised ALERTT1 trial

Comparing Continuous With Flash Glucose Monitoring In Adults With Type 1 Diabetes (ALERTT1) examined whether switching from first-generation intermittently scanned continuous glucose monitoring (isCGM) without alerts to real-time continuous glucose monitoring (rtCGM) with alert functionality offers additional benefits to adults with type 1 diabetes. The extension of the randomised ALERTT1 trial assessed the effect of switching from isCGM to rtCGM up to 24 months. In this 6-month, double-arm, parallel-group, non-masked, randomised, controlled trial, done across six hospitals in Belgium, 254 adults aged 18 years or older with type 1 diabetes previously using isCGM were randomly assigned (1:1) to rtCGM with alerts (intervention; n=127) or isCGM without alerts (control; n=127). Upon completion of the 6-month trial, the control group switched to rtCGM (is-rtCGM group), and the intervention group continued rtCGM (rt-rtCGM group). The extension focused on within-group changes in time in range (TIR; 3·9–10·0 mmol/L; primary outcome), HbA1c, time in clinically significant hypoglycaemia (