Continuous Glucose Monitoring Systems Transform Diabetes Management
Continuous glucose monitoring systems (CGMs) are revolutionizing diabetes management from a “one size fits all” to a personalized medicine approach to care. The small wearable devices provide continuous, dynamic blood glucose information throughout the day and evening, enabling people to proactively manage their diabetes according to their unique needs.
“Unlike traditional fingerstick blood glucose tests, CGMs provide continuous feedback at regular intervals, 24/7, so that people can see the real-time effects of food, exercise, and daily routines on their blood glucose levels and modify their behavior accordingly.
“CGMs empower people with diabetes to be in control of their own healthcare by providing actionable insights that help keep their glucose levels in their target range,” says Tiffany Yeh, MD, Division of Endocrinology, Diabetes, and Metabolism at NewYork-Presbyterian Weill Cornell Medicine. “Unlike traditional fingerstick blood glucose tests, CGMs provide continuous feedback at regular intervals, 24/7, so that people can see the real-time effects of food, exercise, and daily routines on their blood glucose levels and modify their behavior accordingly. In this age of telemedicine, these devices enable clinicians to remotely review the information to optimize their care.”
The FDA approved the first CGMs in 1999, but the devices still required daily fingerstick monitoring and calibration. Then, in 2016, the FDA approved CGMs to replace daily fingerstick testing for the management of Type 1 and Type 2 diabetes, which significantly enhanced the quality of life of people living with diabetes.
The patch device, about the size of a quarter, is applied to the skin of the abdomen or back of the arm, and contains a small subcutaneous (or under the skin) sensor that continuously measures the amount of glucose in body fluid. The device transmit real-time glucose readings every 5 minutes to a compatible display device, such as a mobile medical app on a cell phone, and it will trigger an alarm when a patient’s blood sugar enters a danger zone, rising too high (hyperglycemia) or dropping too low (hypoglycemia). The devices must be calibrated with a finger stick test at regular intervals to ensure accuracy.
“Studies show that CGMs reduce hemoglobin A1c, which is the average blood glucose over 2 to 3 months,” explains Dr. Yeh. “While A1c has long been the gold standard test of blood glucose management, endocrinologists are now moving toward ‘time in range,’ the concept of spending more than 70% of the time in a blood glucose range of 70-180 mg/dL, to maintain healthy blood glucose levels. However, time in range has been hard to achieve without CGM data and day-to-day treatment decision making.”
“These devices give parents peace of mind that their child’s diabetes is under control, which is particularly important if the child is playing sports or has night time fluctuations"
Four CGM devices are currently available on the market for people young as age two. “These devices give parents peace of mind that their child’s diabetes is under control, which is particularly important if the child is playing sports or has night time fluctuations, says Dr. Yeh. “While approved for use in pregnant women in Europe, CGMs are not approved for pregnant women in the US, although studies show that CGMs improve neonatal outcomes.”
“Another population that could potentially benefit from CGMs are people with pre-diabetes because the devices help them see how their blood sugar responds to diet and exercise, which allows them to proactively change their behavior,” she adds.
you can wear these devices 10-14 days without needing to calibrate with a finger stick test
CGMs have come a long way since they entered they first market four years ago. “The biggest development is you can wear these devices 10-14 days without needing to calibrate with a finger stick test,” says Dr. Yeh. “Also, the size of the patch used to be a lot thicker and larger and was bulky to wear, now they’re thin, small and discreet.”
However, the devices still pose some challenges, such as when hardware or set-up issues disable alarms and alerts and issues concerning connectivity. “Users must still calibrate the using a fingerstick blood sample, and certain medications, such as acetaminophen, may falsely raise glucose readings,” adds Dr. Yeh.
CGM devices can only be obtained with a doctor’s prescription. Most major insurers (including Medicare and Medicaid) require a Prior Authorization before extending coverage for CGM.
As with most medical devices, patient education and counseling helps ensure successful use. “Here at Weill Cornell Medicine, our certified diabetes educators meet with patients to teach them how to use the device and what activities to avoid,” explains Dr. Yeh. “If a patient’s blood sugar is well-controlled, we recommend either a televisit or an in-person visit every three months. If a patient has just started using a CGM and is experiencing lots of fluctuations, we will ask him or her to come back as frequently as necessary to meet treatment goals.”
CGM technology is continuously evolving to meet the health and lifestyle needs of diabetes patients. “CGMs will soon have longer wear time and will have improved accuracy and connectivity,” says Dr. Yeh. “Eventually these devices will enable clinicians to exclusively use time in range instead of relying on A1c, which is a big mindset change in the endocrinology world. These improvements will help people proactively manage their diabetes, so they can enjoy living their life.”