Comparing real-time and intermittently scanned continuous glucose monitoring in adults with type 1 diabetes (ALERTT1): a 6-month, prospective, multicentre, randomised controlled trial

Abstract

Background: People with type 1 diabetes can continuously monitor their glucose levels on demand (intermittently scanned continuous glucose monitoring [isCGM]), or in real time (real-time continuous glucose monitoring [rtCGM]). However, it is unclear whether switching from isCGM to rtCGM with alert functionality offers additional benefits. Therefore, we did a trial comparing rtCGM and isCGM in adults with type 1 diabetes (ALERTT1).

Methods: We did a prospective, double-arm, parallel-group, multicentre, randomised controlled trial in six hospitals in Belgium. Adults with type 1 diabetes who previously used isCGM were randomly assigned (1:1) to rtCGM (intervention) or isCGM (control). Randomisation was done centrally using minimisation dependent on study centre, age, gender, glycated haemoglobin (HbA_1c), time in range (sensor glucose 3·9-10·0 mmol/L), insulin administration method, and hypoglycaemia awareness. Participants, investigators, and study teams were not masked to group allocation. Primary endpoint was mean between-group difference in time in range after 6 months assessed in the intention-to-treat sample. This trial is registered with ClinicalTrials.gov, NCT03772600.

Findings: Between Jan 29 and Jul 30, 2019, 269 participants were recruited, of whom 254 were randomly assigned to rtCGM (n=127) or isCGM (n=127); 124 and 122 participants completed the study, respectively. After 6 months, time in range was higher with rtCGM than with isCGM (59·6% vs 51·9%; mean difference 6·85 percentage points [95% CI 4·36-9·34]; p<0·0001). After 6 months HbA_1c was lower (7·1% vs 7·4%; p<0·0001), as was time <3·0 mmol/L (0·47% vs 0·84%; p=0·0070), and Hypoglycaemia Fear Survey version II worry subscale score (15·4 vs 18·0; p=0·0071). Fewer participants on rtCGM experienced severe hypoglycaemia (n=3 vs n=13; p=0·0082). Skin reaction was more frequently observed with isCGM and bleeding after sensor insertion was more frequently reported by rtCGM users.

Interpretation: In an unselected adult type 1 diabetes population, switching from isCGM to rtCGM significantly improved time in range after 6 months of treatment, implying that clinicians should consider rtCGM instead of isCGM to improve the health and quality of life of people with type 1 diabetes.

Funding: Dexcom.