The Impact of Hybrid Closed-loop Insulin Delivery in Type 1 Diabetes on Glycemic Control and PROMs

The Medtronic Minimed 670G system is a form of hybrid closed-loop insulin delivery. The Medtronic MiniMed 670G system automatically adjusts basal insulin every five minutes based on CGM readings to reach a glucose target of 120 mg/dL, the SmartGuard Auto Mode. Patients still need to enter their carbohydrate intake and administer meal-time and correction boluses. Before Auto Mode is introduced, the Medtronic MiniMed 670G system has to be worn in Manual Mode. In contrast to Auto Mode, Manual Mode features an insulin stop up to 30 minutes before or when reaching preset low limits (suspend before/on low) and an automatic insulin restart when blood sugar levels recover. During Manual Mode the pump 'becomes familiar with' the daily insulin need of the patient. This information will be used when in Auto Mode.

The Medtronic Minimed 780G system differs in several aspects from the MiniMed 670G system. In Auto Mode, the user can choose from two target levels for even more stricter glucose control (100 mg/dL and 120 mg/dL) and correction boluses are now automated without the need of user interaction. When administering meal boluses, no capillary blood glucose value is required. The safety feature to exit from Auto Mode to Manual Mode was too strict in the Minimed 670G. In the Minimed 780G this is more flexible to overcome this frequently reported patient frustration.

The Tandem t:slim X2 Control-IQ consists of the Tandem t:slim X2 insulin pump with Control-IQ technology, and integrates with the Dexcom G6 CGM-device via Bluetooth. Blood glucose readings for calibration are not required. The Tandem t:slim X2 Control-IQ automatically adjusts basal insulin based on CGM readings to reach a glucose target range between of 112-160 mg/dL. Patients still need to enter their carbohydrate intake and administer meal-time boluses, but the system automatically increases the basal insulin dose or gives automated correction boluses in case of high blood glucose levels. The technology offers optional settings for sleep and exercise, with different glucose targets in order to match the insulin need during these activities. New versions of the pump software can be downloaded and installed remotely via the user's own computer.