ULP Wireless Update

Non-invasive monitoring next step for diabetes sufferers

Non-invasive monitoring next step for diabetes sufferers

The next generation of wearables will use powerful Bluetooth Low Energy SoCs to monitor a wide range of health metrics including blood glucose

Wireless technology will play a key role in a new generation of blood-glucose monitoring which aims to consign uncomfortable finger pricking to history

Glucose is a type of sugar used to power muscles and organs. But continuously high blood-glucose levels can lead to cardio-vascular disease, kidney damage, and sight deterioration.


In healthy people, hormones from the pancreas maintain an optimum level of glucose in the blood. Diabetics aren’t so lucky. The disease robs them of the body’s natural blood-glucose management and requires them to constantly monitor blood glucose levels and administer control using medication, diet, and exercise.


Diabetes is on the rise and, according to the International Diabetes Federation (IDF), cost healthcare authorities a staggering $673 billion in 2015. It’s a major pandemic that wireless technology can help manage.


Testing, testing

Diabetics typically measure blood-glucose levels using meters with test strips containing an enzyme that reacts to glucose in a blood sample. Results are accurate, but the downside is the constant finger-pricking which is both uncomfortable and carries the risk of infection.


Other technology has further eased diabetic management. For example, wirelessly-connected continuous glucose monitors (CGMs) are becoming more common. The CGM sends data to a paired smartphone and triggers alarms when blood glucose exceeds set thresholds. The disadvantage of CGMs is that the technology is still invasive.


Non-invasive blood glucose measurement promises to eliminate the drawbacks of finger-pricking and GCMs. The problem is that it’s proving very difficult to commercialize with some companies working on the technology for four decades without payback. And there are several possible techniques with no clear leader. A 2012 study listed ten non-invasive blood glucose measurements including several forms of spectroscopy, transdermal, and ultrasound, but noted that none had yet resulted in a commercial product.


Wearables makers are spending millions on non-invasive blood-glucose measurement and tend to favor spectroscopy because it uses similar optical sensors to those already proven for heart-rate measurement. By shining a light through the skin the wearables makers hope to detect signs of glucose using the optical sensors. The major challenge is that the glucose signal is tiny and tends to be swamped by ambient light. To achieve sufficient sensitivity, prototypes use large, heavy sensors weighing several hundred grams that only work well in dim ambient light.


Other companies have chosen not to crack the non-invasive glucose measurement problem directly, rather to introduce an app that correlates the conventional wirelessly-transmitted data from a wearable against independent blood readings so users can track the effect of exercise on their blood glucose. However, while this will help to improve management and reduce the frequency of finger pricking as confidence in the effects of an exercise routine increases, it doesn’t eliminate the problem entirely.


Today’s wearables, such as the bong 3 HR from Chinese smart wearables company, bong, rely on technology such as Nordic’s nRF52832 SoC because it offers a single-chip solution for Bluetooth Low Energy (Bluetooth LE) wireless connectivity to smartphones, tablets, and PCs. And the chip’s embedded 64MHz, 32-bit ARM Cortex M4F microprocessor handles the complex algorithms required to compute real-time metrics such as calories burned, heart rate, baseline heart rate measurement, and heart rate alerts.


However, adding blood glucose functionality to a wearable that already supports exercise metrics demands even more from the Bluetooth LE SoC. Nordic’s recently-released nRF52840 SoC builds on the success of the nRF52832 but offers greater performance, including 1MB Flash and 256kB RAM to support demanding application software, and Bluetooth 5’s range, throughput, power saving, and security enhancements. The SoC has been specifically designed for the most demanding Bluetooth LE applications such as next-generation wearables.


Manufacturing (and getting approval for) a medical-grade, non-invasive blood-glucose monitoring wearable is likely to challenge even the world’s largest electronics company and could therefore still be some years from market. But in the next few years expect to see “lifestyle-advice only” wearables—powered by SoCs like Nordic’s nRF52840—providing a guide to blood glucose levels with around +/- 20 percent accuracy - at least enabling diabetics to identify trends, troughs, and peaks. While finger-pricking will be around for a while, next generation wearables promise to significantly reduce its frequency.