Long-Term Performance of Two Systems for Automated Insulin Delivery in Adults With Type 1 Diabetes: An Observational Study

Abstract

Aims: To compare glycaemic outcomes for two automated insulin delivery (AID) systems, the Tandem Control IQ (CIQ) and the MiniMed 780G (MM780G).

Material and methods: In this observational study, we evaluated 60 days of glycaemic data from 139 persons with type 1 diabetes (CIQ: 79 persons, MM780G: 60 persons), who had an active glucose sensor time ≥ 85%.

Results: The time with AID was median 620 (IQR, 439-755) days for CIQ users and 509 (429-744) days for MM780G users (p = 0.26). The last HbA1c before initiation of AID was 59.7 mmol/mol in CIQ and 60.1 mmol/mol in MM780G (p = 0.88). The time with an active glucose sensor was higher for CIQ than MM780G (median 98.5 (97.4-98.0)% vs. 96.5 (94.9-97.0)%, p < 0.001). Time in range (TIR, glucose 3.9-10.0 mmol/L) was lower in CIQ than MM780G (mean 68.9% ± 11.4% vs. 73.7% ± 12.0%, p = 0.02) as was time in tight range (TITR) (glucose 3.9-7.8 mmol/L) (43.0% ± 12.2% vs. 48.4% ± 12.7%, p = 0.01). The difference in TIR (4.2 (95% CI 1.0-7.5)%, p = 0.01) and TITR (5.0 (1.4-8.6)%, p < 0.01) remained statistically significant in a multiple regression model controlling for various baseline variables. Time with an absolute rate of glucose change > 1.5 mmol/L/15 min was higher in CIQ than MM780G (9.4 (IQR, 7.2-13.3)% vs. 7.4 (5.2-10.4)%, p < 0.001).

Conclusions: The CIQ system had a higher active glucose sensor time but a lower TIR, TITR, and a higher time with a rapid glucose rate of change than the MM780G system.

Keywords: automated insulin delivery; continuous glucose monitoring; glucose rate of change; glucose time in range; type 1 diabetes.

FIGURE 1

Twenty‐four hour variation of glucose time in range (3.9–10.0 mmol/L) (A) and glucose presented as median (IQR). Red colour for the CIQ system and blue for the MM780G system.

FIGURE 2

Histogram of the distribution of glucose rate of changes (RoC) with indication of SD for the t location scale distribution. For the CIQ system, the curve (red) was characterised by a location parameter −0.05 (mmol/L/15 min), SD 1.05 (mmol/L/15 min), shape parameter 0.63 and degrees of freedom 3.12. For the MM780G system (blue), the mean location parameter was −0.03 (mmol/L/15 min), SD 0.98 (mmol/L/15 min), shape parameter 0.54 and degrees of freedom 2.89. The vertical dotted lines represent RoC of ± 1.5 mmol/L/15 min.