Abstract
Dear Editor,
Recently published review article regarding the impact of technology on impaired awareness of hypoglycemia in type 1 diabetes by Berry et al. 1 was of great interest to us. As the authors argued, remarkable progress has been made regarding the sensor accuracy, convenience, and ease of use of glucose monitoring devices, and they are now essential tools for daily blood glucose management for people with diabetes. The use of continuous glucose monitoring (CGM) may be selected for optimal glycemic management, and can influence lifestyle and the level of motivation for treatment. 2 In addition, for patients who are well educated in the use of CGM devices, low-glucose alerts are an effective means of avoiding hypoglycemia. 3 However, this usefulness is based on the assumption that the monitoring equipment is functioning and coordinating with linked devices correctly. 4 Here, we report an instructive case of hypoglycemic coma that we concluded to be the result of sensor device dysfunction after an automatic smartphone operating system (OS) update.
A woman in her late 40s with type 1 diabetes had been treated using continuous subcutaneous insulin infusion therapy for several years. She principally used an intermittently scanned CGM (isCGM) system as a blood glucose monitoring device and the appropriate smartphone application for sensing. She was not taking any medications that could have affected the accuracy of isCGM and had never experienced any problems related to isCGM before. An automatic update of her smartphone OS was performed between the evening of day X-1 and the early morning of day X. At approximately 04:00 h, she woke up, realizing that she had hypoglycemia, and treated herself with oral glucose. The isCGM hypoglycemia alert did not sound, and the patient went back to sleep. A few hours later, she was found by her husband in a state of hypoglycemic coma. Although emergency medical care was required, the patient regained consciousness without any aftereffects. When the application was checked, it was found that the sensor glucose values had not been recorded, owing to a sensor error from 06:00 h, and therefore the hypoglycemia alert was not activated (Figure 1). The patient attached a new sensor, but this also stopped working owing to a similar sensing error, such that it did not detect another episode of hypoglycemia that occurred during the evening of the same day. Therefore, the OS was switched to the other version, after which there were no similar incidents.
Daily sensor glucose data evaluated by isCGM and the time course for the reported case. After an automatic update of the operating system, the patient experienced persistent hypoglycemia early the next morning. Although the patient self-treated her hypoglycemia, the smartphone application subsequently failed to detect the isCGM device, and she entered hypoglycemic coma and required emergency treatment. Even after changing to a new sensor, this sensor error continued to occur.
The OS of the device that a patient is using can be automatically updated unexpectedly, and the latest version of the OS may not necessarily be compatible with the appropriate isCGM. The FDA recommends turning off automatic updates, 5 but this may not be widely known. Therefore, close collaboration between healthcare professionals, patients, and CGM device manufacturers regarding device management is important for patient safety.
