Sensors and smart devices: Fingerstick testing obsolete for diabetes patients?

Sensors and smart devices: Fingerstick testing obsolete for diabetes patients?

Last Updated on January 20, 2017 by Joseph Gut – thasso

January 19, 2017 – This announcement by the American Food & Drug Administration (FDA) from December 20, 2016, must sound like heaven in the ears of educated patients, technical geeks, and particularly diabetes patients alike. Just see for yourself (announcement largely unedited):

Apple Watch and diabetes monitoring by way of the Dexcom G5 Mobile Continuous Glucose Monitoring System. Other smart devices are going to work as well.

The U.S. Food and Drug Administration today (December 20, 2016) expanded the approved use of Dexcom’s G5 Mobile Continuous Glucose Monitoring System to allow for replacement of fingerstick blood glucose (sugar) testing for diabetes treatment decisions in people 2 years of age and older with diabetes. This is the first FDA-approved continuous glucose monitoring system that can be used to make diabetes treatment decisions without confirmation with a traditional fingerstick test. The system was previously approved to complement, not replace, fingerstick testing for diabetes treatment decisions.

“The FDA works hard to help ensure that novel technologies, which can reduce the burden of daily disease management, are safe and accurate,” said Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health. “Although this system still requires calibration with two daily fingersticks, it eliminates the need for any additional fingerstick blood glucose testing in order to make treatment decisions. This may allow some patients to manage their disease more comfortably and may encourage them to have routine dialogue with their health care providers about the use of real-time continuous glucose monitoring in diabetes management.”

Because the body’s ability to control blood sugar levels is impaired in people with diabetes, patients must regularly test and monitor their blood sugar. This is traditionally done multiple times per day by taking a blood sample from the fingertip (known as a “fingerstick” sample) and testing it with a blood glucose meter. Results indicate if glucose levels are too high (hyperglycemia) or too low (hypoglycemia), helping patients and their health care providers make appropriate diabetes management decisions.

The G5 Mobile Continuous Glucose Monitoring System uses a small sensor wire inserted just below the skin that continuously measures and monitors glucose levels. Real-time results are sent wirelessly every five minutes to a dedicated receiver and a compatible mobile device (e.g., smart phone or tablet) running a mobile app. Alarms and alerts indicate glucose levels above or below user-set thresholds. The system measures glucose in fluid under the skin and must be calibrated at least two times per day using blood obtained from fingerstick tests. However, additional daily fingerstick blood tests are generally no longer necessary because unlike other continuous glucose monitoring systems, results from this device can now be used directly by patients to make diabetes treatment decisions without confirmation from a traditional fingerstick test.

According to the U.S. Centers for Disease Control and Prevention, more than 29 million people in the U.S. have diabetes. People with diabetes either don’t make enough insulin (type 1 diabetes) or can’t use insulin properly (type 2 diabetes). When the body doesn’t have enough insulin or can’t use it effectively, blood sugar builds up in the blood. High blood sugar levels can lead to heart disease; stroke; blindness; kidney failure; and amputation of toes, feet or legs.

The FDA evaluated data from two clinical studies of the G5 Mobile Continuous Glucose Monitoring System. These studies included 130 adults and children aged 2 years and older with diabetes. All studies included a seven-day period where system readings were compared to blood glucose meter values, as well as to a laboratory test method that measures glucose values. No serious adverse events were reported during the studies.

Risks associated with use of the system may include hypoglycemia or hyperglycemia in cases where information provided by the device is inaccurate and used to make treatment decisions or where hardware or set-up issues disable alarms and alerts, as well as skin irritation or redness around the device’s adhesive patch. Users are warned that the system must be calibrated using a fingerstick blood sample at least once every 12 hours and that taking any medications containing acetaminophen while wearing the system may falsely raise glucose readings.

For patients, one of the more complicated issues in this concept might actually be the insertion part of the sensor by the patient. Having been in pharmacovigilance for quite a while, and having received all these reports from patients, physicians, and health care providers alike of patients handling medical  devices, the author has huge experience on what can go wrong in every day life when patients (or health care providers including physicians for that matter) have to handle the insertion of a device like in the present case the sensor. As a point in case, follow this tutorial video on the insertion process of the Dexcom Sensor.



Ph.D.; Professor in Pharmacology and Toxicology. Senior expert in theragenomic and personalized medicine and individualized drug safety. Senior expert in pharmaco- and toxicogenetics. Senior expert in human safety of drugs, chemicals, environmental pollutants, and dietary ingredients.