Hybrid Closed-Loop Therapy in Adults With Type 1 Diabetes and Above-Target HbA(1c): A Real-world Observational Study

OBJECTIVE: We explored longitudinal changes associated with switching to hybrid closed-loop (HCL) insulin delivery systems in adults with type 1 diabetes and elevated HbA(1c) levels despite the use of intermittently scanned continuous glucose monitoring (isCGM) and insulin pump therapy. RESEARCH DESIGN AND METHODS: We undertook a pragmatic, preplanned observational study of participants included in the National Health Service England closed-loop pilot. Adults using isCGM and insulin pump across 31 diabetes centers in England with an HbA(1c) ≥8.5% who were willing to commence HCL therapy were included. Outcomes included change in HbA(1c), sensor glucometrics, diabetes distress score, Gold score (hypoglycemia awareness), acute event rates, and user opinion of HCL. RESULTS: In total, 570 HCL users were included (median age 40 [IQR 29–50] years, 67% female, and 85% White). Mean baseline HbA(1c) was 9.4 ± 0.9% (78.9 ± 9.1 mmol/mol) with a median follow-up of 5.1 (IQR 3.9–6.6) months. Of 520 users continuing HCL at follow-up, mean adjusted HbA(1c) reduced by 1.7% (95% CI 1.5, 1.8; P < 0.0001) (18.1 mmol/mol [95% CI 16.6, 19.6]; P < 0.0001). Time in range (70–180 mg/dL) increased from 34.2 to 61.9% (P < 0.001). Individuals with HbA(1c) of ≤58 mmol/mol rose from 0 to 39.4% (P < 0.0001), and those achieving ≥70% glucose time in range and <4% time below range increased from 0.8 to 28.2% (P < 0.0001). Almost all participants rated HCL therapy as having a positive impact on quality of life (94.7% [540 of 570]). CONCLUSIONS: Use of HCL is associated with improvements in HbA(1c), time in range, hypoglycemia, and diabetes-related distress and quality of life in people with type 1 diabetes in the real world.