Skin patches could revolutionise glucose monitoring
Posted on 26 October 2017
Electrochemical analysis of sweat using soft bioelectronics on human skin provides a new route for non-invasive glucose monitoring without painful blood collection. However, sweat-based glucose sensing still faces many uncertainties.
‘Self-monitoring of blood glucose remains an important part of a diabetic patient’s management of their disease. Finger prick (capillary) glucose is the most widely used method, but can become quite a burden as it is painful. Other methods of testing glucose have therefore recently been explored,’ says Dr Marli Conradie Endocrinologist at Mediclinic Durbanville.
‘Examples of these are devices that extract capillary blood much less painfully by using a “vacuum” technique. Other devices are worn for a longer period of time (some even up to 3 months) and measure interstitial (the solution surrounding the tissue cells) glucose with some having the added advantage of not requiring calibration with finger pricks at all.’
Interstitial fluid and sweat-based collection
The only minimally-invasive technology for glucose monitoring to have received approval by the US Food and Drug Administration is the GlucoWatch Biographer according to University of Bath Professor of Pharmaceutical Sciences, Dr Richard Guy. ‘This device combines an on-board glucose sensor with the use of an electric current to extract interstitial fluid sample through intact skin,’ he says. He adds that after the first flurry of marketing about seven years ago, it was commercially unsuccessful for various reasons.
The GlucoWatch has been revisited recently. The detection of glucose in sweat has revealed an alternative route to determine the appropriate quantity of diabetes medication needed. The most promising version of this device connects electrically to a portable electrochemical that wirelessly transmits data to a remote mobile device (such as a smartphone). According to Dr Guy, the device integrates components that capture sweat from the skin, and sensors for glucose, pH, humidity, temperature and mechanical strain, with a micro-needle drug delivery system that responds to heat. He cautions there is a lot more research required before the system is practically feasible and commercially viable.
Ink – a permanent solution?
People living with diabetes who like body art may soon be able to add a colour-changing tattoo to their collection. The ink, which contains biosensors, changes colour from blue to brown when blood sugar levels increase. Instead of relying on finger-prick tests or disposable patches, the ink provides a long-term solution to measuring glucose levels. The researchers from MIT and Harvard Medical School are still developing the system so this too remains a futuristic concept.
‘The challenges of using these technologies in South Africa would be to make sure they are cost-effective compared to other methods available. Accuracy is also of paramount importance as any diabetic needs to be able to trust the result given to him or her by any self-monitoring device,’ adds Dr Conradie.
As Dr Guy concludes: ‘The holy grail of diabetes management — a non-invasive feedback system combining glucose monitoring and responsive drug delivery — is not yet at hand. However, researchers have moved the field closer to this coveted prize.’
Richard Guy is at the University of Bath, Department of Pharmacy & Pharmacology, Bath BA2 7AY, UK. e-mail: firstname.lastname@example.org
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