Over 30 million people in the United States (over 9%) have been diagnosed with diabetes. About 25% of people with diabetes will experience a foot ulcer (DFU) in their lifetime. Unresolved DFUs may lead to sepsis and are the leading case of lower limb amputations. DFU rates can be reduced by screening patients with diabetes to enable risk-based interventions. Skin temperature assessment has been shown to reduce the risk of foot ulceration. While several tools have been developed to measure plantar temperatures, they measure temperature once a day or are designed for clinic use only. In this report, wireless sensor-embedded socks designed for daily wear are introduced, which perform continuous temperature monitoring of the feet of persons with diabetes in the home environment. Combined with a mobile app, this wearable device informs the wearer about temperature increases in one foot relative to the other, to facilitate early detection of ulcers and timely intervention.
A pilot study was conducted to assess the accuracy of sensors used in daily wear socks, obtain user feedback on how comfortable sensor-embedded socks were for home use, and examine whether observed temperatures correlated with clinical observations.
Temperature accuracy of sensors was assessed both prior to incorporation in the socks, as well as in the completed design. The measured temperatures were compared to the reference standard, a high precision thermostatic water bath in the range 20℃ to 40℃. Thirty-five (35) patients with diabetic peripheral neuropathy, 18 years and older, were enrolled in a single-site study conducted under an IRB-approved protocol to evaluate the usability of the sensor embedded socks and to correlate the observed temperatures with clinical findings.
The temperatures measured by the standalone sensors were within 0.2℃ of the reference standard. In the sensor-embedded socks, across multiple measurements for each of the six sensors, a high agreement (R2 = 1) between temperatures measured and the reference standard was observed. Patients reported that the socks were easy to use and comfortable, ranking them at a median score of 9 or 10 for comfort and ease of use on a 10-point scale. Cases are presented showing that the temperature differences observed between the feet was consistent with clinical observations.
We report the first use of wireless continuous temperature monitoring for daily wear and home use in patients with diabetes and neuropathy. The wearers found the socks to be no different from standard socks. The temperature studies conducted show that the sensors used in the socks are reliable and accurate at detecting temperature, and the findings matched clinical observations. Continuous temperature monitoring is a promising approach as an early warning system for foot ulcers, Charcot foot, and re-ulceration.