Medtronic MiniMed 670G Auto Mode: Implications for Clinical Practice

Abstract

Background: The Medtronic MiniMed 670G System was the first FDA approved hybrid closed loop system for users seven years of age and older. The system monitors glucose and can automatically adjust the delivery of long acting or basal insulin based on the user’s glucose reading while in Auto Mode. Previous research has demonstrated that 670G Auto Mode use has improved glycemic control in patients (PTs) with Type 1 diabetes as young as 2 years of age and as old as 75 years of age compared to open loop Manual Mode. Objective: This retrospective study seeks to determine if the results of improved glycemic control, as evidenced by decreased HbA1c levels, can be replicated in real life/uncontrolled environments, when PTs are wearing the 670G system in Auto Mode. Methods: The medical records of PTs prescribed the 670G System at a pediatric endocrinology center were reviewed. PTs who did not use the system in Auto Mode were excluded. PTs who did not have HbA1c values before and at least 3 months after using the 670G system in Auto Mode were also excluded. HbA1c values were collected either as a serum sample at a local laboratory or a capillary sample at the center using Siemens DCA Vantage HbA1c Analyzer. 52 PTs aged 6-25 yrs met these criteria for analysis. Results: When analyzing the PTs as a whole, there was a significant decrease in HbA1c from 8.64% ± 1.51% to 7.81% ± 1.35% (p= 0.024). 63.5% of all PTs showed a decrease in HbA1c. 3.9% of PTs showed no change to their HbA1c. 32.7% of PTs showed an increase in HbA1c. Of those 63.5% of PTs who showed improved glycemic control, 51.5% had data in their charts to reflect their percentage of time in auto mode, which was an average of 54.32% ± 27.28%. There was no significant difference in HbA1c between males and females both prior (p=0.2) and post (p=0.1) treatment, nor was there a significant difference in the mean change of HbA1c between males and females (p=0.50). The PTs who were in auto mode greater than 25% of the time (n=15) showed significantly improved glycemic control with HbA1c levels decreasing from 8.13% ± 1.16% to 7.37% ± 0.58% (P= 0.04). The PTs who were in auto mode greater than 50% of the time (n=10), showed improved glycemic control with HbA1c levels decreasing from 7.87% ± 0.68% to 7.27% ± 0.46% (P= 0.046). There was a significant difference in the mean change of HbA1c between PTs whose adherence was known to be less than 25% (n=9) compared to those whose adherence was known to be greater than 25% (n=15). The difference in mean HbA1c prior treatment was not significant between these groups, yet the difference in mean HbA1c was significant post treatment. Conclusion: Our data demonstrates that the 670G system can significantly improve glycemic control in an uncontrolled environment. Adherence is an important factor in the outcome in this treatment modality. Bluetooth monitoring of patient blood sugar levels may significantly improve adherence and glycemic control.