Multinational Home Use of Closed-Loop Control Is Safe and Effective

Abstract

Objective: To evaluate the efficacy of a portable, wearable, wireless artificial pancreas system (the Diabetes Assistant [DiAs] running the Unified Safety System) on glucose control at home in overnight-only and 24/7 closed-loop control (CLC) modes in patients with type 1 diabetes.

Research design and methods: At six clinical centers in four countries, 30 participants 18-66 years old with type 1 diabetes (43% female, 96% non-Hispanic white, median type 1 diabetes duration 19 years, median A1C 7.3%) completed the study. The protocol included a 2-week baseline sensor-augmented pump (SAP) period followed by 2 weeks of overnight-only CLC and 2 weeks of 24/7 CLC at home. Glucose control during CLC was compared with the baseline SAP.

Results: Glycemic control parameters for overnight-only CLC were improved during the nighttime period compared with baseline for hypoglycemia (time <70 mg/dL, primary end point median 1.1% vs. 3.0%; P < 0.001), time in target (70-180 mg/dL: 75% vs. 61%; P < 0.001), and glucose variability (coefficient of variation: 30% vs. 36%; P < 0.001). Similar improvements for day/night combined were observed with 24/7 CLC compared with baseline: 1.7% vs. 4.1%, P < 0.001; 73% vs. 65%, P < 0.001; and 34% vs. 38%, P < 0.001, respectively.

Conclusions: CLC running on a smartphone (DiAs) in the home environment was safe and effective. Overnight-only CLC reduced hypoglycemia and increased time in range overnight and increased time in range during the day; 24/7 CLC reduced hypoglycemia and increased time in range both overnight and during the day. Compared with overnight-only CLC, 24/7 CLC provided additional hypoglycemia protection during the day.

Trial registration: ClinicalTrials.gov NCT02137512.

Figure 1

Time <70 mg/dL (A), between 70 and 180 mg/dL (B), and >180 mg/dL (D) and mean glucose (C) by study phase. Bottom and top of each box denote the 25th and 75th percentile, respectively; the horizontal line inside each box denotes the median, and the dot denotes the mean. N = 29 participants; 1 participant was excluded owing to missing baseline CGM data. Night CLC, overnight-only CLC.

Figure 2

Twenty-four-hour CGM sensor glucose comparing baseline with overnight-only CLC (A) and 24/7 CLC (B). N = 29 participants; 1 participant was excluded owing to missing baseline CGM data. Bottom and top curves denote the 25th and 75th percentile, respectively, and the curves with dots or triangles denote the median. As seen in the two dashed-line rectangles, 24/7 CLC (B) consistently improved daytime hypoglycemia from baseline compared with overnight-only CLC (B compared with A).

Figure 3

Participant-level overall (day and night) time <70 mg/dL and time in range (70–180 mg/dL) by baseline and study phase. N = 29 participants; 1 participant was excluded owing to missing baseline CGM data. A: Time <70 mg/dL during overnight-only CLC by baseline. B: Time <70 mg/dL during 24/7 CLC by baseline. C: Time in range during overnight-only CLC by baseline. D: Time in range during 24/7 CLC by baseline.