Background: The Medtronic predictive low-glucose management (PLGM) algorithm automatically stops insulin delivery when sensor glucose (SG) is predicted to reach or fall below a preset low-glucose value within the next 30 min, and resumes delivery after hypoglycemia recovery. The present study evaluated the PLGM algorithm performance of the MiniMed™ 670G system SmartGuard™ "suspend before low" feature in children aged 7-13 years with type 1 diabetes (T1D).
Method: Participants (N = 105, mean ± standard deviation of 10.8 ± 1.8 years) underwent an overnight in-clinic evaluation of the "suspend before low" feature with a preset low limit of 65 mg/dL. After exercise, frequent sample testing (FST) was conducted every 5 min if values were <70 mg/dL; every 15 min if 70-80 mg/dL; and every 30 min if >80 mg/dL. First-day performance of the Guardian™ Sensor 3 glucose sensor and continuous glucose monitoring system was also evaluated.
Results: Activation of the "suspend before low" feature occurred in 79 of the 105 participants, 79.7% (63/79) did not result in SG falling below 65 mg/dL. Mean glucose at activation was 102 ± 19 mg/dL and the initial insulin suspension duration was 87.5 ± 32.7 min. Four hours after insulin resumption, mean reference glucose was 130 ± 42 mg/dL. Mean absolute relative difference between the FST reference glucose and SG values on the first day of sensor wear was 11.4%. For the 26 participants in whom the "suspend before low" feature did not activate, none involved a reference glucose value ≤65 mg/dL, suggesting that the PLGM algorithm performed as intended.
Conclusion: In children aged 7-13 years with T1D, the "suspend before low" feature of the MiniMed 670G system demonstrated a hypoglycemia prevention rate of nearly 80% after exercise and did not involve rebound hyperglycemia. There were no events of severe hypoglycemia during the evaluation.
Keywords: Automated insulin delivery.; Hybrid closed loop; Hypoglycemia; Insulin pump suspension; Pediatrics; Predictive low glucose management; Type 1 diabetes.