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Review
. 2019 Jul;13(4):645-663.
doi: 10.1177/1932296819851790. Epub 2019 May 26.

A Review of Continuous Glucose Monitoring Data Interpretation in the Age of Automated Insulin Delivery

Laya Ekhlaspour  1 , Ideen Tabatabai  1 , Bruce Buckingham  1
Affiliations
Review

A Review of Continuous Glucose Monitoring Data Interpretation in the Age of Automated Insulin Delivery

Laya Ekhlaspour et al. J Diabetes Sci Technol. 2019 Jul.

Abstract

Using a continuous glucose monitor (CGM) improves glycemic control in patients with type 1 diabetes. The ambulatory glucose profile (AGP) has been recommended as a standard method for reporting CGM data. However, in recently developed automated insulin delivery (AID) systems, a standard format for reporting data has not yet been developed. Instead, reports are specific to each system being used. Currently, the only FDA approved AID system is a hybrid closed-loop insulin pump. In these systems, the patient is still required to announce a meal, respond to alerts, and keep the system in automated insulin delivery. The integrated pump and sensor information provides insights into how the system is performing, and how to make changes to tunable parameters, such as carbohydrate to insulin ratios. The reports also offer a window into human behavior related to performing diabetes tasks, responding to alarms, reasons for exiting HCL, and how glycemic goals are being met. This article reviews the pump and CGM data provided by several of the current closed-loop systems with a focus on systems that are currently approved in the United States (MiniMed™ 670G, Tandem Basal:IQ) and those used by patients using do-it-yourself systems. A step-wise approach to reviewing the nuances of these systems is provided. The comparison may reinforce the importance of the continued need for streamlining a standard report for providers to be able to interpret the CGM data of these systems.

Keywords: MiniMed 670G; Tandem Basal IQ; closed loop; continuous glucose monitoring system; do-it-yourself; type 1 diabetes.

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Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: LE and IT have none. BB has research support from the NIH (DP3DK104059, DP3DK101055, DK-14-024), Helmsley Foundation, Medtronic Diabetes, Insulet, Dexcom, and Tandem. He is on advisory boards for Convatec, Medtronic, and Tidepool, and has consulted for Tandem. Diabetes.

Figures

Figure 1.
Figure 1.
Assessment and Progress Report.
Figure 2.
Figure 2.
Weekly Review report.
Figure 3.
Figure 3.
Daily detail graphs with Auto Mode versus Manual Mode. A) Existing Daily report. B) Upcoming Daily report
Figure 4.
Figure 4.
Safe Basal.
Figure 5.
Figure 5.
Data Table with more detail on boluses, Auto Mode exits, and calibrations.
Figure 6.
Figure 6.
Assessing total basal insulin when in HCL and comparing it to preset basal total.
Figure 7.
Figure 7.
Be mindful of sensor accuracy when judging success of HCL.
Figure 8.
Figure 8.
Fake Carbs.
Figure 9.
Figure 9.
Sensor backfill.
Figure 10.
Figure 10.
Patients should inspect infusion sets with prolonged SG>300 mg/dl while in HCL.
Figure 11.
Figure 11.
The dashboard on t:connect. (A) The dashboard. (B) The Basal:IQ section.
Figure 12.
Figure 12.
Therapy Timeline Report. (A) Therapy detail. Types of bolus and basal are displayed as colored bars on this report: Food Bolus (light blue bar), Correction Bolus (dark blue bar), Basal (yellow area), Temporary Basal (orange area). (B)  Log Book. Data including date and time, BG, carb amount, and insulin delivery.
Figure 13.
Figure 13.
Blood Glucose Trends Report. (A) Hourly View. (B) Daily View.
Figure 14.
Figure 14.
CGM Hourly Report and Time of Day Boxes.
Figure 15.
Figure 15.
Activity Summary.
Figure 16.
Figure 16.
Tidepool reports with the 670G in Auto Mode. (A) Daily Detail view. (B) Basal rate delivery interface. (C) Auto Mode exit interface.
Figure 17.
Figure 17.
Tidepool reports with the Tandem Basal:IQ. (A) Daily Detail view and time in range. (B) Basal rate delivery interface.
Figure 18.
Figure 18.
Nightscout report for DIY closed-loop pump. (A) Day-to-day report and AID basal (blue) seen in daily report. (B) Daily stats. (C) Percentile chart (modal day). (D) Treatments.
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