Optimizing a Hybrid Closed Loop System in Type 1 Diabetes: A Case Report

We present the optimization of a hybrid closed-loop (HCL) insulin pump system in a type 1 diabetes (T1D) patient in the first 3 months of using the Minimed 670G. An 11-year-old female with 7 years of T1D history started using the Minimed 670G HCL system at our center. The patient had been using the Medtronic Veo insulin pump without a sensor for almost 4 years with HbA1c levels between 7.8% and 10.2%. We introduced the Minimed 670G to improve overall glucose control, improve quality of life and lessen the diabetes burden. Insulin pump characteristics of the Minimed Veo pump were used as the initial setting in the HCL system. The optimization of the Minimed 670G in the next 3 months led to the following changes: an insulin-to-carbohydrate ratio (ICHR) from 1 to 10 g in the morning period (6 a.m. to 12 a.m.) and 15–12 g for the rest of the day (12 p.m. to 6 a.m.); an active insulin time from 4 to 3 h and insulin sensitivity factor (ISF) from 120 to 90 mg/dl with no change in target range. The HbA1c level decreased by − 1.3%, and the time in range significantly increased to 77% with SG values of 139 ± 60 mg/dl, sensor wear of 82% and an auto mode period of 84% per week. Health providers should consider immediate adjustment of the bolus wizard settings such as the ICHR, ISF and active insulin time. The HCL system can improve overall glucose control with increased time in the range of sensor glucose values and reduction of HbA1c levels.