Background: Automated Insulin Delivery (AID) devices in type 1 diabetes (T1D) are becoming standard of care, and the need for adaptive AID systems is now well recognized. However, very little is known about how self-treatment behaviors should be adapted to the action of an AID system, especially with hybrid closed-loop (HCL) solutions that still require people with T1D to make several treatment decisions each day.

Methods: A safety and feasibility 8-week study with a randomized two-arm parallel group design was conducted. Both control and experimental groups used a web-based simulation tool, and a commercial AID system (Control-IQ®) enhanced with an auto-titration module (ATM) that adjusted insulin therapy parameters weekly. The experimental group had access to a behavioral adaptation module (BAM) that provided up-to-date risk assessment from CGM data. Primary outcome: Safety assessment of ATM and BAM. Secondary glycemic outcomes: CGM-based metrics computed from the 2-week baseline period and last 2 weeks of treatment data.

Results: Thirty Control-IQ® users completed all study procedures, 17 women and 13 men, age: 40±14 years, diabetes duration: 23±14 years, HbA1c: 6.6%±0.5%. No severe hypoglycemia, DKA, or other serious adverse events were reported. No significant changes were observed in time in 70-180 mg/dL. Changes in time in 70-140 mg/dL and mild hyperglycemia 180-250 mg/dL were significantly different between control (-3.1% and +3.1%) and experimental (+3.6% and -0.7%) groups (P=0.and 0.04) . Overnight time in 70-140 mg/dL increased significantly in the experimental group (6.8%, 95% CI [0.6%,12.9%], P=0.03) . Time < 70 mg/dL decreased in both groups, but significantly only in the control group (-0.9%, 95% CI [-1.6%,-0.3%], P=0.vs. -0.1%, 95% CI [-0.7%,0.5%], P=0.71) .

Conclusions: Results from this pilot study suggest that combining HCL AP with behavioral adaptation feedback to the user is safe and effective.


P.Colmegna: None. R.Mcfadden: None. C.Fabris: None. B.Lobo: Other Relationship; Dexcom, Inc., Research Support; Dexcom, Inc. M.C.Oliveri: None. R.Nass: None. S.A.Brown: Research Support; Dexcom, Inc., Insulet Corporation, Roche Diagnostics USA, Tandem Diabetes Care, Inc., Tolerion, Inc. B.Kovatchev: Other Relationship; Dexcom, Inc., Johnson & Johnson, Novo Nordisk, Sanofi, Research Support; Dexcom, Inc., Novo Nordisk, Tandem Diabetes Care, Inc., Speaker's Bureau; Dexcom, Inc., Tandem Diabetes Care, Inc.


National Institutes of Health (2R01DK085623-10)

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at