A Practical Approach to
Prescribing CGM Technologies
for Type 2 Diabetes

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A1C and CGM use

Real-time continuous glucose monitoring (CGM) devices have been found to reduce hemoglobin A1C levels and the frequency of hypoglycemia in patients with insulin-treated diabetes. These benefits are most significant when the CGM device is used consistently over time.¹

Detailed information
on glucose levels

CGM can reduce or eliminate the need for fingerstick blood glucose testing and can provide more detailed information about average glucose levels as well as glucose trends during fasting, exercise, and after meals, both of which can identify the reason for and alert the patient to episodes of impending or actual hypoglycemia.²

PCPs and CGM ²⁻⁴

Gudeline recomendations

The American Diabetes Association (ADA) recommends that CGM should be offered to adults with diabetes who are using basal insulin or multiple daily insulin injections for diabetes management.1,5

Insurance coverage ⁶

Device Selection

Selection of the type of CGM device should be individualized based on the needs, preferences, and skill level of the person with diabetes, and/or their caregiver.¹
Online tools to help with decision-making, such as DiabetesWisePro or the ADA, offer information and resources for healthcare providers when choosing CGM devices.7,8

Insurance coverage ⁷⁻⁹

Abbott Freestyle Libre 14-Day
Dexcom G6
Dexcom G7
Abbot Freestyle Libre
Frequency of GlucoseReadings
Measures glucose every minute; records glucose level every 15 mins
Glucose readings sent to receiver/smart device every 5 mins
Glucose readings sent to receiver/smart device every 5 mins
Measures glucose every minute; records glucose level every 15 mins
Data Type
Unblinded
Unblinded
Unblinded
Unblinded
Approved Ages
≥ 2 yrs
≥ 2 yrs
≥ 2 yrs
≥ 2 yrs
Location for Placement
Back of Upper Arm
Abdomen (ages 2+), upper buttocks (ages 2-17)
Upper arm (ages 7+), upper buttocks (ages 2-6)
Upper arm (ages 7+), upper buttocks (ages 2-6)
Sensor Life
14 days
10 days
10 days
10 days
Finger Stick Calibration
No
No
No
No
Warm-up Time
1 hr
2 hr
30 minutes
30 minutes
Potential InterferingSubstances
Hydroxyurea; high dose acetaminophen (> 4 g/day any dose)
Hydroxyurea
Hydroxyurea
Hydroxyurea
Alerts/Alarms
No; trend arrows
Measures glucose every minute; records glucose level Yesevery 15 mins
Yes
Unblinded
Mean Absolute RelativeDifference (MARD)
9%
9%
8.20%
9%

Patient education

When a CGM is prescribed, the person with diabetes (and/or their caregiver, as appropriate) should receive education and training in use of the device, including the importance of consistently wearing the CGM and sharing access to their blood glucose data. ¹

Sharing data

Sharing of CGM data and reports with diabetes care providers can help determine whether any change in the diabetes care regimen is needed. Some people also choose to share the CGM information with family members or friends, so that those individuals might be alerted to any blood glucose problems that arise. ¹

Periodic evaluation of use

The person’s use of the CGM device should be reevaluated over time, including assessment of the percentage of time the device is worn, the completeness and quality of data collected, and discussion of and support for any mechanical or other technical problems that may arise. ¹

Pregnancy and CGM

When used in addition to fingerstick blood glucose testing before and after meals, CGM devices can help women with diabetes and pregnancy meet their hemoglobin A1C targets.¹

Interfering substances

Some substances, such as high-dose (>4 g/day) acetaminophen, >500 mg/day ascorbic acid (vitamin C), and hydroxyurea may interfere with the CGM and result in sensor readings that are higher than the actual glucose level.

Patients being considered for CGM use, and those with CGM readings that are inconsistent with fingerstick blood glucose or hemoglobin A1C levels, should be assessed for the use of these interfering substances and their use discontinued if possible. ¹

Make sure you don’t miss this!

  • Although 90% of individuals with diabetes are managed in the primary care setting, a recent survey showed that just over one-third of primary care providers (PCPs) had prescribed CGMs.
  • CGM devices have been found to reduce hemoglobin A1C levels and the frequency of hypoglycemia.
  • The Centers for Medicare and Medicaid Services’ (CMS) local coverage determination (LCD) expanded coverage of CGM to people with diabetes using basal insulin only and to people with problematic hypoglycemia.
  • Selection of the type of CGM device should be individualized, and online tools exist to help compare and choose appropriate devices.
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References

  1. American Diabetes Association Professional Practice Committee. 7. Diabetes Technology: Standards of Care in Diabetes–2024. Diabetes Care. 2024;47(Suppl 1):S126-S144. doi:10.2337/dc24-S007
  2. Continuous glucose monitoring (CGM). AAFP website. Accessed February 12, 2024. https://www.aafp.org/family-physician/patient-care/care-resources/continuous-glucose-monitoring.html.
  3. Unger J, Kushner P, Anderson JE. Practical guidance for using the FreeStyle Libre flash continuous glucose monitoring in primary care. Postgrad Med. 2020;132(4):305-313.doi:10.1080/00325481.2020.1744393

  4. Oser TK, Hall TL, Dickinson LM, et al. Continuous glucose monitoring in primary care: understanding and supporting clinicians’ use to enhance diabetes care. Ann Fam Med. 2022;20(6):541-547.
  5. Hughes MS, Addala A, Buckingham B. Digital technology for diabetes. N Engl J Med. 2023;389(22):2076-2084. doi: 10.1056/NEJMra2215899
  6. Local coverage determination (LCD): glucose monitors. Centers for Medicare & Medicaid Services website. Accessed February 12, 2024. https://www.cms.gov/medicare-coverage-database/view/lcd.aspx?LCDId=33822.
  7. Consumer guide: CGMs. American Diabetes Association website. Accessed February 12, 2024. https://consumerguide.diabetes.org collections/cgm.
  8. Device library. DiabetesWisePro website. Updated January 9, 2024. Accessed February 12, 2024. https://pro.diabeteswise.org/en/devices/device-library.
  9. Consult QD. What to know in an expanding continuous glucose monitoring landscape. Cleveland Clinic website. Accessed February 12, 2024. https://consultqd.clevelandclinic.org/what-to-know-in-an-expanding-continuous-glucose-monitoring-landscape/. May 16, 2023.