Eversense sensor and transmitter – interesting radiological images seen on plain X-rays of upper arms
A 43-year-old woman presents to discuss continuous glucose monitor (CGM) technologies. She has type 1 diabetes mellitus diagnosed at age 14 and has been on insulin pump since 2001 which was upgraded to MedtronicTM 630G in July 2017. She has adequate glycemic control (A1c 7.3%), but finger-stick blood glucose levels fluctuate widely with occasional hypoglycemia. Past surgical history was noncontributory. She exercises regularly, walking 30 minutes several times per day with a goal of 7000 steps per day. She tried to use a CGM in 2018 (Medtronic) but she discontinued the CGM due to frequent alarms. Patient reports the alarms were not due to highs or lows, but due to difficulty with obtaining accurate readings. Patient consulted an endocrine clinic to improve blood glucose monitor with new CGM technology. Patient subsequently developed bilateral arm pain intermittently for which primary care provider ordered X-ray of both arms which shows the EversenseTM sensor and transmitter on the right arm and the sensor alone on the left arm CGM devices measure the glucose level of interstitial fluid which correlate well with plasma glucose. Glucose levels are measured every 5-15 minutes, depending on the device. The EversenseTM sensor is placed in the upper arm by a physician. Once inserted, it continuously measures glucose levels for up to 3 months. The EversenseTM smart transmitter sits over the sensor on the upper arm. The transmitter is waterresistant, rechargeable, and can be easily removed. Not only can the transmitter can send data to the EversenseTM Mobile App but it can also provide on-body vibration alerts when glucose level fluctuates high or low. The EversenseTM Mobile App receives and displays the data easy-to-read charts and graphs, making it easy for patients to monitor their blood glucose. The difference between EversenseTM CGM system compared to other CGM devices are that (a) there is no weekly sensor self-insertion since EversenseTM CGM lasts up to 3 months, (b) sensor is placed under the skin; thus, no concern about it falling off, (c) no separate receiver is required; data, trends and alerts can be viewed on mobile device; (d) highs and lows can be detected quickly. Many CGM devices allow patients to share their blood glucose data in real time with friends, relatives, and caregivers using a smartphone app, which may be particularly important when patients have hypoglycemia. The case demonstrates an interesting radiological finding of an implantable CGM sensor, and also the importance of awareness of various CGM systems with different safety advantages to improve diabetic care.