Real-World Data Supports Use of Hybrid Closed Loop Therapy in Type 1 Diabetes


Across 31 centers in England, hybrid closed-loop therapy was associated with improvements in HbA1c, sensor glucometrics, and diabetes-related distress in adults with T1D.

Emma G. Wilmot, MBChB, PhD | Image Credit: LinkedIn

Emma G. Wilmot, MBChB, PhD

Credit: LinkedIn

Results from a new real-world observation study supplement existing evidence supporting the use of hybrid closed loop (HCL) insulin delivery systems in people with type 1 diabetes (T1D) and above target hemoglobin A1c (HbA1c).1

Across 31 diabetes centers in England, study data showed the use of HCLs was associated with improvements in HbA1c, continuous glucose monitor (CGM)-derived outcomes, and diabetes-related distress among those with T1D.

“These findings mirror those reported in existing randomized controlled trial data, provide evidence that those findings translate into a less resources real-world setting, and support wider access to HCL therapy in people living with T1D,” wrote the investigative team, led by Emma G. Wilmot, MB ChB, PhD, school of medicine, faculty of medicine and health sciences, University of Nottingham.

Glucose levels among people living with T1D often remain above recommended HbA1c targets. HCL insulin delivery systems combine insulin pump therapy with CGM sensors to automate insulin delivery between meals and overnight and maintain glucose levels at a prespecified target level.

Despite suggesting the benefit of HCL systems for T1D, the generalizability of data from randomized controlled trials can be limited, as study participants were motivated to participate in research and often had baseline HbA1c levels close to the target range. Real-world evidence additionally exists but is limited to single-system studies and similarly includes individuals who were at or near target HbA1c at baseline.

Part of the National Health Service England, the Association of British Clinical Diabetologists (ABCD) Closed Loop Audit Program was designed to assess the real-world effectiveness and safety of HCL systems. The study population included patients attending adult diabetes services with a diagnosis of T1D and managed with an insulin pump and intermittently scanned CGM, with an HbA1c of ≥8.5%. Patients were started on HCL between August - December 2021.

The primary outcome of the analysis was the change in laboratory-derived HbA1c. Secondary outcomes consisted of CGM metrics time in range (TIR; 70 – 180 mg/dL), time below range (TBR; <70mg/dL), glucose management indicator (GMI), diabetes distress score, hypoglycemia awareness, event rates, and user opinion of the HCL on a 7-point Likert scale (1 = strongly negative and 7 = strongly positive).

Baseline data were available for 634 adults across the 31 centers, with follow-up data reported for 570 (89.9%) patients, of whom 91.2% (520 of 570) continued to use HCL. Of the 520 individuals, the median age was 40 years, 40% were female, and 83% were White.

Across the study population, the mean HbA1c reduced from 9.4 ± 0.9% (78.9 ± 9.1 mmol/mol) at baseline, to 7.8 ± 0.8% over a median follow-up of 5.1 months. After adjusting for key covariates, the mean adjusted HbA1c was reduced by 1.7% (95% CI, 1.5 - 1.8; P <.0001) (18.1 mmol/mol [95% CI, 16.6 - 19.6]; P <.0001).

Other metrics experienced an increase with HCL use, with TIR (70–180 mg/dL) rising from 34.2 to 61.9%, a mean increase of 27.8% (95% CI, 26.2 - 29.4; P <.001).Meanwhile, TBR (<70 mg/dL) reduced from 2.1 to 1.6% (P = .01).

Per entry criteria, no study participants were achieving an HbA1c of ≤7.5% (58 mmol/mol) at baseline. At follow-up, 39.4% of users met the HbA1c target and 14.1% achieved HbA1c ≤7.0% (53 mmol/mol). Additionally, at baseline, 0.8% of patients met the recommended glucose targets of ≥70% TIR and <4% TBR, with an increase to 28.2% at follow-up (P <.0001).

In the study population, 96.3% reported they would recommend HCL therapy to others with diabetes, while 94.7% rated HCL therapy as having a positive impact on their quality of life. However, despite technological advances and the positive response from users, investigators noted the current generation of closed-loop systems may not be for every patient.

“It should be noted that a small, but significant proportion of people (8.8%) discontinued use despite all users already being familiar with and established on stand-alone insulin pump therapy,” investigators wrote. “The reasons for this are multifaceted, are not limited purely to technology or equipment issues, and should be explored further in future studies.”


  1. Crabtree TSJ, Griffin TP, Yap YW, et al. Hybrid Closed Loop Therapy in Adults With Type 1 Diabetes and Above-Target HbA1c: A Real-World Observational Study [published online ahead of print, 2023 Aug 11]. Diabetes Care. 2023;dc230635. doi:10.2337/dc23-0635
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