TIME FOR NEEDLE-FREE DIABETES MANAGEMENT

Diabetics are one step closer to blood-free glucose testing, with new developments to a wrist device that can 'suck' fluid through the skin presented to a British conference this week.

Professor Richard Guy and colleagues, from the University of Geneva in Switzerland, announced a new calibration method for the device, called 'GlucoWatch'.

They presented their findings at an Institute of Physics conference on Electromagnetic Methods in Pharmacy and Medicine at the University of Kent in Canterbury, UK.

The new calibration method eliminates the need for users to take constant blood tests to ensure the machine is accurate.

"One of the limitations with GlucoWatch is you have to keep calibrating it, which means you have to do a fingerprick test at the same time," explained Dr Jonathan Shaw, director of clinical research at the International Diabetes Institute in Melbourne.

But the Switzerland researchers think they have a solution to this problem. They are working on a technique that uses iontophoresis to extract sodium ions at the same time as glucose through the skin.

Iontophoresis is the movement of charged substances in and out of the body without the need to make holes in the skin. The technique works because human skin is slightly permeable, and some fluids will pass through the skin if a small electric current is passed over it.

The device then uses a known relationship between the concentration of sodium ions and glucose for calibration, without having to get a blood sample.

The flow of ions into and out of the body through the skin can be controlled by carefully adjusting the current.

Patients are aware of the process happening, according to Dr Shaw, with some reporting discomfort with the use of the watch, and others coming up with skin rashes at the site.

The machines need to be calibrated against blood samples because they are testing interstitial fluid — fluid that sits between cells, not blood itself.

People with type 1 (juvenile-onset) diabetes generally test their blood sugar levels two to four times a day. But their blood sugar levels can vary considerably throughout the day, without them or their doctor being aware of it.

"It's a daily tightrope that they walk," said Dr Shaw.

Wrist devices pull glucose through the skin and into a gel disk where sensors monitor its concentration up to three times an hour.

"One of the things about these devices is we might find out that a patient is going too low overnight, when we are not testing," said Dr Shaw.

"Because these things are testing all the time, we can find out about it."

Ultimately, the idea would be for the patient to self-monitor using one of these devices, with an alarm that would go off if the blood sugar level went too low or too high.

Currently the devices are only licensed for use by doctors. A patient is fitted for one over a couple of days. The machine then stores the results until the doctor can download and analyse them.

Wrist devices are not yet available in Australia.

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