Continuous Glucose Monitoring Provides Durable Glycemic Benefit in Adolescents and Young Adults with Type 1 Diabetes: 12-Month Follow-Up Results

Objective. To further evaluate glycemic outcomes during the observational extension phase of the Continuous Glucose Monitoring (CGM) Intervention for Teens and Young Adults randomized clinical trial (RCT). Subjects and Methods. Following a 26-week RCT comparing CGM with blood glucose monitoring (BGM) in 153 adolescents and young adults aged 14 to <25 years old with suboptimally controlled type 1 diabetes, 70 (89%) participants in the BGM group initiated use of CGM (referred to as BGM–CGM cohort), and 70 (95%) participants in the CGM group continued to use of CGM (CGM–CGM cohort) for an additional 26 weeks. Results. In the CGM–CGM cohort, mean hemoglobin A1c (HbA1c) decreased from 8.9% ± 0.9% (74 ± 9.8 mmol/mol) at randomization to 8.3% ± 1.3% (67 ± 14.2 mmol/mol) at 52 weeks ( $p<0.001$ ); however, significant improvement in time in target range (TIR) 70–180 mg/dL was not observed from prerandomization (38% ± 13%) to 52 weeks (41% ± 18%). Median percent time <70 mg/dL decreased from 3.0% before randomization to 1.1% at 52 weeks ( $p<0.001$ ). In the BGM–CGM cohort, mean HbA1c decreased from 8.9% ± 1.2% (74 ± 13.1 mmol/mol) before CGM initiation to 8.5% ± 1.3% (69 ± 14.2 mmol/mol) after 26 weeks of CGM use ( $p<0.001$ ) and mean TIR increased from 34% ± 12% to 38% ± 15% ( $p=0.01$ ). The median percent time <70 mg/dL decreased from 3.3% before CGM initiation to 1.2% after 26 weeks of CGM use ( $p<0.001$ ). No participants discontinued CGM use during the extension phase. Conclusions. This further evaluation of CGM supports the findings of the preceding RCT that use of CGM improves glycemic control and reduces hypoglycemia in adolescents and young adults with type 1 diabetes. This trial is registered with NCT03263494.