Improvement in Newly Defined Continuous Glucose Monitor Metrics, Extended Hypoglycemia, and Extended Hyperglycemia With Automated Insulin Delivery Initiation in Adults With Type 1 Diabetes.

Objective: Extended hypoglycemia (Ehypo) and extended hyperglycemia (Ehyper) are recently defined continuous glucose monitoring (CGM) metrics by the International Consensus for clinical trials as secondary endpoints for continuous outcomes. This study aims to evaluate the changes in Ehypo and Ehyper before and after automated insulin delivery (AID) initiation in adults with type 1 diabetes (T1D).

Research methods: This is a retrospective single-center study that evaluated Ehypo and Ehyper in addition to other CGM metrics in 154 adults that initiated an AID system. Metrics were compared before and after AID initiation by Wilcoxon signed-rank test.

Results: Median (interquartile range) Ehypo (<70 mg/dL) events/week decreased from 0.1 (0-0.4) to 0 (0-0.1) and Ehyper (>250 mg/dL) events/week decreased from 2.2 (0.9-4.5) to 0.8 (0.3-1.7) (both P < .001) after AID initiation compared with before AID initiation. All other CGM metrics improved after AID initiation. There was a strong positive correlation between Ehyper (>250 mg/dL) and mean glucose (before AID: r = 0.947, after AID: r = 0.894), glucose management indicator (before AID: r = 0.947, after AID: r = 0.887), and time above range (TAR; >180 mg/dL) (before AID: r = 0.957, after AID: r = 0.917) and a strong positive correlation between Ehypo (<70 mg/dL) and time below range (TBR; <70 mg/dL) (before AID: r = 0.823, after AID: r = 0.608) before and after AID initiation, respectively.

Conclusion: Automated insulin delivery initiation significantly improved Ehypo and Ehyper metrics. Ehypo and Ehyper had a strong positive correlation with TBR and TAR, respectively. Ehypo and Ehyper events can be used in addition to TBR and TAR metrics in clinical studies as secondary outcomes.