Department of Pharmaceutical Care, University of Iowa Hospitals & Clinics, Iowa City (Dr. Schleich); Department of Family Medicine, Carver College of Medicine, University of Iowa, Iowa City (Drs. Schleich and Ray) kevin-schleich@uiowa.edu
The authors reported no potential conflict of interest relevant to this article.
The MOBILE trial demonstrated that use of an rtCGM reduced baseline A1C from 9.1% to 8.0% in the CGM group, compared to 9.0% to 8.4% in the non-CGM group.27
Practical utilization of CGMs
Patient education
Detailed patient education resources—for initial setup, sensor application, methods to ensure appropriate sensor adhesion, and app and platform assistance—are available on each manufacturer’s website.
Clinical targets
In 2019, theAdvanced Technologies & Treatments for Diabetes Congress determined that what is known as the time in range metric yields the most practical data to help clinicians manage glycemic control.28 The time in range metric comprises:
time in the target glucose range (TIR)
time below the target glucose range (TBR)
time above the target glucose range (TAR).
A sensor that becomes dislodged can malfunction or lose accuracy. Patients should not try to reapply the sensor; they should remove and discard it and apply a new one.
TIR glucose ranges are modifiable and based on the A1C goal. For example, if the A1C goal is < 7.0%, the TIR glucose range is 70-180 mg/dL. If a patient maintains TIR > 70% for 3 months, the measured A1C will correlate well with the goal. Each 10% fluctuation in TIR from the goal of 70% corresponds to a difference of approximately 0.5% in A1C. Therefore, TIR of approximately 50% predicts an A1C of 8.0%.28
A retrospective review of 1440 patients with CGM data demonstrated that progression of retinopathy and development of microalbuminuria increased 64% and 40%, respectively, over 10 years for each 10% reduction in TIR—highlighting the importance of TIR and consistent glycemic control.29 Importantly, the CGM sensor must be active ≥ 70% of the wearable time to provide adequate TIR data.30