The Efficiency of an Advanced Hybrid Closed Insulin Pump in Patients with Type 1 Diabetes for Improved Blood Glucose Control

Abstract

Background Diabetes technology, especially advanced hybrid closed-loop (AHCL) systems, is rapidly advancing, offering improved glycemic control, reduced hypoglycemia, and reduced treatment burden for patients with type 1 diabetes (T1D). This study aimed to evaluate the clinical efficiency of an AHCL system—the Medtronic MiniMed 780G insulin pump combined with continuous glucose monitoring—among individuals with T1D in real-world clinical settings.

Methods In an observational retrospective study, we identified a cohort of 41 patients (mean age, 47.1 ± 13.7 years; T1D duration, 23.6 ± 13 years; 73.2% female) previously using an insulin pump or those on multiple daily insulin injections, currently using the AHCL system for at least 6 months. Primary outcomes were the changes of the following parameters, before AHCL initiation and at 6 months after treatment; (1) time in range (TIR): time with glucose levels in the range of 70 to 180 mg/dL, (2) time below range (TBR): time with glucose levels below 70 mg/dL, and (3) time above range (TAR): time with glucose levels above 180 mg/dL.

Results Data analysis from 41 patients showed a significant 16.5% ± 13.8% increase in TIR (from 56.6 ± 17.9 to 73.1 ± 10.6%, p < 0.001). Both TBR and TAR decreased by 2.9 ± 4.8% (p = 0.004) and 13.6 ± 16.4% (p < 0.001), respectively. Mean glucose concentration, coefficient of variation, and glucose management indicator significantly improved.

Conclusion The AHCL system effectively improved glucose control regarding TIR, TBR, and TAR. Enhanced glycemic control metrics highlight the potential for wider adoption of AHCL technology.

Keywords

type 1 diabetes - insulin pump - artificial pancreas - closed loop

Introduction

Type 1 diabetes (T1D) is associated with significant morbidity and burden in daily life.[1] Good glycemic control can significantly reduce microvascular and macrovascular complications.[2] Diabetes-related technologies, including insulin pumps and continuous glucose monitoring (CGM), were introduced to improve glycemic control, decrease glucose variability, reduce hypoglycemic events, and improve quality of life.[3]

In September 2016, the U.S. Food and Drug Administration approved the first hybrid closed-loop insulin pump, often called an artificial pancreatic system.[4] This system is designed to automatically adjust basal insulin delivery in response to interstitial glucose levels. These systems are labeled “hybrid” since they continue to require user participation for tasks such as reporting carbohydrate intake and physical exercise to achieve the most optimal outcomes.[5] Controlled trials and field studies have demonstrated remarkable enhancements in glycemic outcomes and reductions in diabetes-related distress. Notably, guided recommendations for its utilization are increasingly evolving.[5] [6]

This service evaluation study aimed to assess the clinical efficiency of the advanced hybrid closed-loop (AHCL) system, utilizing the Medtronic MiniMed 780G insulin pump in conjunction with CGM, in improving diabetes control in people with T1D within the context of real-world application. The AHCL system was introduced in our service at the University Hospital of North Durham in October 2020. This study aims to contribute further to the existing field and community study experience with the AHCL system.

Patients and Methods

Settings and Design

In this observational retrospective study, all adults with T1D initiated on the AHCL system were identified between October 2020 and November 2022. Individuals were transitioned from either another type of insulin pump or multiple daily insulin injection (MDI) therapy to the AHCL system. Patients had to be on the AHCL system for at least 6 months to be included in the study. Individuals not utilizing continuous or intermittent flash glucose monitoring before transitioning to the AHCL system were excluded. Furthermore, patients lacking available glucose parameter data before and 6 months after initiating the AHCL system were excluded.

Data Extraction

Electronic patient records from the diabetes clinic were reviewed for patients' demographic and clinical information. Data were anonymized. Clinical data included the year of T1D diagnosis, the type of treatment before initiating the AHCL system (insulin pump or MDI), the method used for glucose monitoring before initiating the AHCL system (fingerstick testing, intermittent flash, or CGM), and the time of initiating the AHCL system.

Consequently, data were extracted from the LibreView, Dexcom, and CareLink systems. Parameters of glucose control were collected over 1 month before initiating the AHCL system and 6 months after that. The data included percentage time spent in euglycemic (70–180 mg/dL equivalent to 3.9–10 mmol/L), hypoglycemic (<70 mg/dL equivalent to <3.9 mmol/L), and hyperglycemic (>180 mg/dL equivalent to >10 mmol/L) ranges, coefficient of variation (CV) of sensor-measured glucose concentrations, mean glucose level, percentage of sensor use, glucose management indicator (GMI), and the percentage of time the system was in auto mode. Hemoglobin A1c (HbA1c) levels were also collected prior to the commencement of the AHCL system and at the 3- to 9-month interval after that.

Outcome Measures

The primary outcomes were changes in the percentage of time spent within the target range of 70 to 180 mg/dL (time in range [TIR]), time below 70 mg/dL (time below range [TBR]), and time above 180 mg/dL (time above range [TAR]). Secondary outcomes were the changes in mean glucose concentration, CV, GMI, and HbA1C before starting the AHCL system and 6 months after that.

Statistical Analysis

All continuous variables were tested for normality using the one-sample Kolmogorov–Smirnov test. All variables proved to be normally distributed except TBR-prior and senso-use-prior; however, given the number of observations (n = 41), according to the central limit theorem, we were still able to employ means and standard deviation for reporting and the parametric paired t-test for means comparisons. All p-values presented are two-sided. Statistical analysis was undertaken using SPSS 29.0.

Results

After applying the previously mentioned exclusion criteria, 41 patients initiated on the AHCL system between October 2020 and November 2022 were identified. The mean age of all patients was 47.1 ± 13.7 years, and 73.2% were female. The average duration of T1D diagnoses was 23.6 ± 13 years. Twelve patients were on MDI, whereas 29 patients were on other insulin pumps before they transitioned to the AHCL system. Twenty-nine patients were using flash intermittent glucose monitoring, while the remaining 12 were utilizing CGM before commencing the AHCL system.

Before initiating the AHCL system, the frequency of glucose sensor utilization was 74.2 ± 29.3%, and after 6 months on the AHCL system, it was 90.1 ± 11.1%. The duration spent in auto mode at the end point was 92% ± 14.3%.

The time spent within the euglycemic range (TIR) increased from 56.6 ± 17.9 to 73.1 ± 10.6%. The average change was 16.5 ± 13.8% (p < 0.001). Conversely, the time spent within both hypoglycemic (TBR) and hyperglycemic (TAR) ranges decreased by an average of 2.9 ± 4.8% (p = 0.004) and 13.6 ± 16.4% (p < 0.001), respectively. Please refer to [Fig. 1] and [Table 1].

Table 1 Changes in glucose outcomes from baseline to 6 months on AHCL system

Metrics	Baseline	6 mo on AHCL	Treatment difference	p-Value
Time in range %	56.6 ± 17.9	73.1 ± 10.6	16.5 ± 13.8	<0.001
Time below range %	4.4 ± 5.1	1.5 ± 1.3	2.9 ± 4.8	0.004
Time above range %	39 ± 20.3	25.3 ± 10.7	13.6 ± 16.4	<0.001
Mean sensor glucose (mmol/L)	9.5 ± 2	8.4 ± 0.9	1.1 ± 1.7	0.002
CV of sensor glucose concentrations (%)	36 ± 6.7	32.9 ± 4.9	3.2 ± 6.4	0.02
Glucose management indicator (mmol/mol)	56.3 ± 9.7	51.7 ± 5.9	4.6 ± 7.8	0.01

Abbreviations: AHCL, advanced hybrid closed-loop; CV, coefficient of variation; SD, standard deviation.

Note: Data are expressed as mean ± SD. p-Values < 0.025 are significant. Outcomes based on continuous glucose monitoring data are derived from the last 30 days preceding baseline and 6 months on the AHCL system.

Fig. 1 Changes in % time in defined glucose range from baseline to 6 months on the AHCL system.

Changes were more pronounced in the subgroup of patients who were on MDI before transitioning to the AHCL system. The average changes were as follows: 20.5% increase in TIR, 4% decrease in TBR, and 16.5% decrease in TAR. Conversely, in the other subgroups who were using other types of insulin pumps, the changes were as follows: 14.9% increase in TIR, 2.4% decrease in TBR, and 12.4% decrease in TAR.

Mean glucose concentration, CV, and GMI were all significantly reduced, as presented in [Table 1]. Among the 27 patients with available HbA1c data before and within the 3- to 9-month interval on the AHCL system, a reduction of 9.9 ± 8.9 mmol/mol in HbA1c was observed. Of the 41 patients, 25 (59.5%) achieved 70% or more of their time in the euglycemic range.

Discussion

The AHCL system effectively increased time within the glucose target range while reducing time spent in both hyperglycemic and hypoglycemic ranges. These findings are consistent with previous studies and meta-analyses.[7] [8] [9] [10] Notably, patients transitioning from MDI experienced more pronounced improvements in glucose control.

Variability decreased by 3.2 ± 6.4%, and mean glucose concentration and GMI were significantly reduced. Adherence to the AHCL system was strong, with 87.8% of patients spending >80% of their time in auto mode, meeting the recommended benchmark.[11]

In a real-world assessment of the MiniMed 780G System's performance involving 4,120 users from various countries, the average TIR on the AHCL system was 76.2 ± 9.1%, and the average GMI was 6.8 ± 0.3% (equivalent to 51 nmol/L).[12] Our study showed similar results: an average TIR on the AHCL system of 73.1 ± 10.6% and an average GMI of 51.7 ± 5.9 nmol/L.

Furthermore, 61% (n = 25 of 41) of patients successfully achieved the target TIR recommended by the international consensus of more than 70%, correlating with an A1C level of approximately 53 mmol/mol (7%).[13] In England, only about one-third of patients with T1D successfully achieve the National Diabetes Audit HbA1c target of 58 mmol/mol.[14] In contrast, our study showed that 67% of the patients on the AHCL system achieved this target.

One potential bias in our study is the inclusion criterion requiring patients to be on intermittent glucose monitoring or CGM before transitioning to the AHCL system. It is possible that these patients had a higher level of engagement with their diabetes management and a stronger motivation to improve glucose control, aside from their attraction to newer technology. Additionally, patients may have had more frequent contact with clinical staff during the transition to the AHCL system. Therefore, we chose a 6-month evaluation period for post-AHCL system data to allow for potential stabilization and to avoid the initial weeks when patients might pay more attention to glucose control while adapting to the new therapy.

Furthermore, some patients were excluded due to a lack of data before or at 6 months of using the AHCL system. This encourages patients to upload their data for routine future reference and research. Another noteworthy limitation of our study is that the percentages of time spent within different glycemic ranges were not adjusted for variations in CGM usage.

Conclusion

Our data show that in adults with T1D, transitioning to the AHCL system leads to a significant improvement in glucose control, represented by increased TIR, decreased TBR and TAR, and decreased variability, GMI, and HbA1c. Moreover, most cases reached the recommended target for time spent in the euglycemic range in a real-world condition. These results support the increased use of this technology.

Conflict of Interest

None declared.

Author's Contributions

All the named authors participated in data collection and analysis and drafting and revising the manuscript.

Compliance with Ethical Principles

County Durham and Darlington Foundation NHS Trust approved the study.

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Publikationsverlauf

Artikel online veröffentlicht:
11. Juli 2024