Continuous glucose monitoring (CGM)  technology is utilized by patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) who require insulin injections or pumps. CGM devices constantly sense and relay glucose concentration data from the interstitial fluid to a mobile phone, smart watch, or receiver. Depending on the device, glucose concentrations are measured every 5 to 15 minutes. CGM provides a comprehensive picture of glucose fluctuations across time, and fluctuations can be linked to life events such as meals, exercise, sleep, or medication administration.

Studies have shown that the use of these devices, compared with self-monitoring blood glucose meters, improved patient glycemic control. In addition, research has shown that with improved glycemic control and subsequent decreases in hypoglycemic events, patients have improved clinical outcomes and overall health-related quality of life.

The integration of CGM technology into clinical practice has expanded rapidly and is associated with numerous clinical benefits, including accuracy, affordability, and accessibility. Blood glucose meters require frequent and often painful finger sticks throughout the day to obtain a single reading at a moment in time. In contrast, CGMs provide continuous real-time glucose readings 24/7 to a compatible smart device or receiver and also have proven accuracy without the need for frequent, painful, and inconvenient finger sticks.

The American Diabetes Association (ADA) notes that CGM devices are particularly valuable for alerting patients to previously unrecognized hypoglycemic episodes. The glucose management indicator (GMI) and data on time in range (TIR), hypoglycemia, and hyperglycemia are available to providers and patients via the Ambulatory Glucose Profile (AGP) report, which offers visual cues and recommendations to assist in data interpretation and treatment decision-making.

The 2022 ADA guidelines recommend that patients who take rapid-acting insulin should use a CGM. The ADA also expanded this recommendation to include patients who take only long-acting insulin (often referred to as basal insulin). Research on CGM use in patients with T2DM indicates that the devices can help those on basal-only insulin enhance their day-to-day glucose management. The 2022 guidelines also recommend CGM for all children with T1DM or T2DM who use rapid-acting insulin. CGM devices are categorized as real-time CGM (rtCGM), intermittently scanned CGM (isCGM), and professional CGM.

ADA CGM Recommendations

• rtCGM orisCGM should be offered for diabetes management in adults with diabetes on multiple daily injections (MDI) or continuous SC insulin infusion (CSII) who are capable of using devices safely (either by themselves or with a caregiver). The selection of device should be made based on patient circumstances, desires, and needs.
• rtCGM or isCGM can be used for diabetes management in adults with diabetes on basal insulin who are capable of using devices safely (either by themselves or with a caregiver). The choice of device should be made based on patient circumstances, desires, and needs.
• In patients on MDI and CSII, rtCGM devices should be used as close to daily as possible for maximal benefit. CGM devices should be scanned frequently, at a minimum of once every 8 hours.
• When utilized as an adjunct to pre- and postprandial BGM, CGM can help reach A1C targets in diabetes and pregnancy.
• Periodic use of rtCGM or isCGM or use of professional CGM can be helpful for diabetes management in circumstances when continuous use of CGM is not appropriate, desired, or available.
• Skin reactions due to either irritation or allergy should be evaluated and addressed to aid in successful use of devices.
• Standardized, single-page glucose reports from CGM devices with visual cues, such as the ambulatory AGP report, should be considered as a standard summary for all CGM devices.
• TIR is associated with the risk of microvascular complications and can be used for assessment of glycemic control. Additionally, time below target and time above target are helpful parameters for evaluation of the treatment regimen.

Currently, there are four CGM devices FDA approved for use in patients with diabetes: Dexcom G6 (Dexcom), Medtronic Guardian Connect, FreeStyle Libre (Abbott), and the implantable Eversense (Ascensia Diabetes Care/Senseonics).

Dexcom was one of the first developers of CGM technology, introducing the first-ever real-time CGM, and its current product, Dexcom G6, uses a sensor that last for 10 days, requires no calibration, and is approved for patients as young as age 2 years. The Medtronic Guardian Connect is approved for those aged 14 years to 75 years and includes a sensor that needs to be changed every 7 days. Freestyle Libre 3 includes a 14-day sensor, and no finger-stick calibrations are required. Eversense E3 is the only implantable sensor device and requires a visit to the primary healthcare provider every 6 months to change the sensor. It also provides silicone-based, fresh-daily adhesive for comfort. Eversense requires twice-daily finger-stick calibration and is the only CGM that has a distinct on-body vibe alert when a patient is hypoglycemic or hyperglycemic.

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

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