Insulin requirements for basal and auto-correction insulin delivery in advanced hybrid closed-loop system: 4193 days’ real-world data of children in two different age groups

Abstract

Background: The insulin requirements of people with type 1 diabetes (T1D) can vary throughout the day due to factors such as biorhythm, exercise, and food intake. The MiniMed 780G system delivers micro boluses to adjust basal insulin and delivers auto-correction boluses to meet insulin needs when micro bolus increases are insufficient. Through analysis of MiniMed 780G data, this study investigates the variations in insulin requirements throughout the day. Methods: 4193 days’ pump and continuous glucose monitoring (CGM) data of 34 children using MiniMed 780G were collected from Medtronic CareLink. Micro and auto-correction boluses were analyzed on an hourly basis for two age groups: below nine years old and above nine years old. Glycemic metrics were analyzed based on International CGM consensus. Results: The mean age was 12.3 years and mean duration of diabetes was 6.1 years. The mean time in range (TIR) and glucose management indicator (GMI) were 80.5% and 6.6%, respectively. The micro bolus (basal) ratio between 05.00 and 07.00 was significantly higher than the ratio between 10.00 and 03.00 (P <.01), whereas micro bolus was significantly lower between 19.00 and 21.00 than those between 00.00 and 10.00 (P <.001). The auto-correction ratio between 21.00 and 00.00 was significantly higher than those between 03.00-17.00 (P <.001) and 19.00-21.00 (P =.008), whereas auto-correction was significantly lower between 07.00 and 10.00 than those between 10.00 and 03.00 (P <.001). The micro bolus ratio was significantly higher in children below nine years old than in children above nine years old between 21.00-00.00 (P =.026) and 00.00-03.00 (P =.003). Conclusion: The basal insulin need follows a diurnal pattern with two significantly different periods—high between 00.00 and 10.00 and low between 10.00 and 00.00. The auto-correction rates are low between 05.00 and 10.00 and show an increasing pattern peaking between 21.00 and 00.00. These findings are compatible with the dawn and reverse dawn phenomena.