Increased proportion of time in hybrid closed-loop "Auto Mode" is associated with improved glycaemic control for adolescent and young patients with adult type 1 diabetes using the MiniMed 670G insulin pump

Abstract

The Medtronic MiniMed 670G system delivers insulin to patients with type 1 diabetes mellitus (T1DM) using either its hybrid closed-loop (HCL) "Auto Mode" feature or an open-loop mode. In this retrospective, cross-sectional analysis, we quantified the association between time in Auto Mode and both haemoglobin A1c (HbA1c) and time in range (TIR, sensor glucose 70-180 mg/dL) among 96 paediatric and young adult patients with T1DM. The median percentage time in Auto Mode was 38.5% (interquartile range 0%-64%). The percentage time in Auto Mode significantly correlated with HbA1c after adjustment for covariables (β = -0.008, P = 0.014). Each daily 3.4-h increase in Auto Mode time was associated with a 0.1% decrease in HbA1c. Auto Mode time was also correlated with TIR after adjustment for covariables (β = 0.14, P = 0.02): for each daily 8.6-h increase in Auto Mode time, TIR increased by 5%. While Auto Mode use was low, increased time in Auto Mode was associated with a significantly lower HbA1c and increased TIR. These findings emphasize the importance of identifying strategies to improve the ease of use of HCL systems.

FIGURE 1

Participant characteristics. Violin plots depict the frequency distribution of the data, with wider sections representing a higher density of participants and narrower sections representing a lower density of participants. Solid vertical line represents zero participants. Additional data depicted in the violin plot include median (thick dotted line) and interquartile range (thin dotted lines), see Table S1 (Supporting Information) for numeric median and interquartile range values. Delta HbA1c depicts change in HbA1c from just before initiation of MiniMed 670G use and time of data collection. Abbreviations: BG, blood glucose; HbA1c, haemoglobin A1c; SG, sensor glucose; TIR, time in range

FIGURE 2

Bivariate and multivariate linear regression analysis. A, Scatterplot depicting bivariate analysis of the effect of Auto Mode time (%) on HbA1c (%). B, Scatterplot depicting bivariate analysis of effect of Auto Mode time (%) on TIR (%). C, Auto Mode time and sensor wear time prediction of HbA1c. Scatterplot depicting predicted HbA1c from a linear model using sensor wear time and Auto Mode time as predictors. Light blue shaded points represent higher predicted HbA1c, dark blue shaded points represent lower predicted HbA1c. D, Correlates with HbA1c and TIR in multilinear regression analysis. Abbreviations: BG, blood glucose; HbA1c, haemoglobin A1c; SG, sensor glucose; TIR, time in range. *Significant P <0.05