Review

Using continuous glucose monitoring data in daily clinical practice

Thomas W. Martens, MD, Gregg D. Simonson, PhD and Richard M. Bergenstal, MD
Cleveland Clinic Journal of Medicine October 2024, 91 (10) 611-620; DOI: https://doi.org/10.3949/ccjm.91a.23090

Article Figures & Data

Figures

  • Figure 1
    Figure 1

    Example of an Ambulatory Glucose Profile Report. (A) The time-in-ranges graph quickly shows whether glycemic goals are being met and whether action is needed. Average glucose and glucose management indicator metrics provide additional information about the need to take action. Glucose variability reports variations over the course of the report period. Increased variability is a risk factor for hypoglycemia. (B) The ambulatory glucose profile curve presents a 24-hour picture of all glucose readings collected during the report period. (C) Ambulatory daily glucose profiles are thumbnails of daily values.

    ©2024 International Diabetes Center, Minneapolis, MN. Used with permission. Visit AGPreport.org for more information.

  • Figure 2
    Figure 2

    Patient’s Ambulatory Glucose Profile Report.

    ©2024 International Diabetes Center, Minneapolis, MN. Used with permission. Visit AGPreport.org for more information.

Tables

  • TABLE 1

    Currently available continuous glucose monitoring systems

    Type of systemDescriptionExamples
    Real-timePatient-owned
    Measures and displays data continuously (real-time)
    Stores data for retrospective analysis    		Freestyle Libre 3
    Dexcom G6 and G7, Stelo (over the counter)
    Guardian 3 and 4 and Simplera
    Eversense E3
    Intermittently scannedPatient-owned
    Measures glucose continuously but only displays data when swiped by a reader or smartphone
    Also known as “flash” glucose monitoring    		Freestyle Libre 2, Rio (over the counter)
    ProfessionalClinic-owned system placed on patient in office
    Typically worn for 7–14 days
    Glucose data may be blinded (both systems) or unblinded (Dexcom G6 Pro) to the patient
    Provides data to support medication and lifestyle changes, guide shared decision-making, and identify hypoglycemia    		Freestyle Libre Pro
    Dexcom G6 Pro
  • TABLE 2

    Glucose targets in healthy and at-risk adults

    Glucose valuesTarget levels
    Healthy nonpregnant adultsOlder and high-risk adults
    Time above range
    > 250 mg/dL< 5%< 10%
    > 180 mg/dL< 25%< 50%a
    Time in range
    70–180 mg/dL> 70%> 50%
    Time below range
    < 70 mg/dL< 4%b< 1%
    < 54 mg/dL< 1%NA

    • ↵a Includes values > 250 mg/dL.

    • ↵b Includes values < 54 mg/dL.

    • Based on information from reference 15.

  • TABLE 3

    Case presentation: clinical data

    Demographics
    Male, age 65
    Body mass index: 42.7
    Blood pressure: 127/75 mm Hg
    Social history: single, no children, retired
    Medical history
    22-year history of type 2 diabetes
    Hypertension
    Hypercholesterolemia
    Diabetic neuropathy
    Diabetic retinopathy
    Peripheral vascular disease
    Health habits
    Nonsmoker, occasional alcohol
    No regular physical activity
    Eats 3 meals per day, often with evening snacks
    Current diabetes medications
    Metformin extended release 1,000 mg 2 times per day
    Dulaglutide 4.5 mg (maximum dose) once weekly
    Insulin glargine 60 units/day at bedtime
    Insulin lispro 10 units with meals
    Laboratory results
    Hemoglobin A1c 8.5% (reference range 4–5.6)
    Fasting blood glucose 165 mg/dL (70–99)
    Estimated glomerular filtration rate > 60 mL/minute/1.73 m2
  • TABLE 4

    Coding for continuous glucose monitoring

    CPT codeDescriptionComments
    95249Personal (patient-owned) CGM: sensor placement, hook-up, calibration, patient training, and printoutOne-time code for initial start-up and education
    95250Professional CGM (office-owned CGM), sensor placement, hook-up, calibration, patient training, removal of sensor, and printoutBilling code covers the cost of sensors and placement by clinician/staff
    95251CGM data analysis and interpretation with report by clinicianCan be billed no more frequently than every 30 days
    Coding guidelines
    72 hours of data are required for billing any of these codes.
    -25 modifier for CGM codes can be used if billing for CGM interpretation on the same day as a Problem Visit code (99212-99215).
    If a significant and separately identifiable service took place:

    • 99212-99215: Pre-CGM evaluation (+) -25 95249: CGM start-up and instruction

    • 99212-99215: E and M code for problem visit (+) -25 95251: CGM analysis, interpretation, and report.

    • CGM = continuous glucose monitoring; CPT = current procedural terminology

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