Hybrid Closed-Loop Insulin Delivery in Type 1 Diabetes During Supervised Outpatient Conditions.

Area of Science:

• Endocrinology
• Biomedical Engineering
• Diabetes Technology

Background:

• Type 1 diabetes management requires continuous glucose monitoring and insulin delivery.
• Hybrid Closed-Loop (HCL) systems represent an advancement in automated insulin delivery.
• Evaluating the efficacy and safety of novel HCL systems is crucial for clinical adoption.

Purpose of the Study:

• To assess the efficacy and safety of the Medtronic Hybrid Closed-Loop (HCL) system in individuals with type 1 diabetes.
• To compare the performance of HCL system using default versus personalized parameters.
• To investigate the impact of meal carbohydrate estimation accuracy on glycemic control.

Main Methods:

• A supervised outpatient study involving nine subjects with type 1 diabetes.
• Utilized a prototype HCL system with a sensor-augmented insulin pump and an Android-based control algorithm.
• Compared closed-loop control using default and personalized parameters, with meal carbohydrate intake estimated via metabolic kitchen, dietician, or subject estimates.

Main Results:

• The HCL system achieved an overall 80% time in range (70-180 mg/dL) with minimal hypoglycemia (0.79% time <70 mg/dL).
• Personalized HCL parameters resulted in significantly improved glucose control (137 ± 37 mg/dL mean glucose) compared to default parameters (158 ± 49 mg/dL mean glucose).
• Meal carbohydrate estimation method did not significantly impact postprandial glycemia, with most subjects underestimating intake.

Conclusions:

• The Medtronic HCL system is both efficacious and safe for managing type 1 diabetes.
• Personalized HCL parameters enhance glycemic control, leading to increased time in range and reduced time below range.
• Accurate estimation of meal carbohydrates did not appear to be a critical factor for improving postprandial glycemic control in this study.