Continuous glucose monitoring (CGM) allows patients with diabetes to monitor their blood sugar more closely by obtaining readings all through the day and night without having to get a blood sample from their fingertips. This type of system is especially useful for patients who test frequently, are at high risk of hypoglycemia, and who take insulin.
CGM systems allow the user to wear a sensor device that is applied to the skin and uses a small wire that is inserted under the skin to measure glucose in interstitial fluid. Sensors are worn from 7-14 days. If blood sugar levels are rapidly changing, then fingertip blood should be tested to get more accurate readings. Interstitial fluid glucose levels are about 5-10 minutes behind blood glucose levels. This can be important if readings are being used to determine when or how much medication to take.
Some products have an alarm feature that can alert a patient when glucose levels are too low or too high, allowing for rapid treatment to be given to restore normal glucose levels. CGM systems can also communicate with a smart phone app to display data and allow the patient to see trends. Data can also be shared with family, friends, or clinicians. Alerts can be sent to contacts of the patient’s choice warning of dangerous low blood sugars. This is an important safety feature for elderly patients, those who live alone, or children.