Cheap, effective system for constant blood glucose monitoring on cards

In a breakthrough that could greatly help diabetes treatment, scientists have developed a continuous glucose-monitoring system that changes colour when glucose levels rise.

Before glucose is added, the hydrogel glucose meter is blue.  Photo courtesy of Chunjie Zhang

The material, which is developed by Paul Braun and graduate student Chunjie Zhang of the University of Illinois, has a precise wavelength shift and doctors and patients may be able to use it for automatic insulin dosing.

The sensor is made of hydrogel, a soft elastic jelly-like material, laced with boronic acid compounds. Boronic acid binds to glucose, causing the gel to swell and expand as the glucose concentration rises.

Embedded within the hydrogel is a photonic crystal made of tiny, carefully arranged beads. A photonic crystal is like a mirror that only reflects one wavelength of light while the rest of the spectrum passes through. As the hydrogel expands, the reflected colour shifts from blue to green to red.

Lead researcher Braun said that there are significant limitations to current continuous glucose monitoring technologies and the systems available today all have some combination of limited sensitivity, limited precision and frequent recalibration.

''Using today's systems, you can determine trends in glucose levels, but without frequent recalibration, you don't have the accuracy or reliability to use that to make insulin dosing decisions or to drive autonomous dosing.'' He said.

The colour-changing material is simple and low-cost to manufacture, and a square inch of hydrogel could be enough for up to 25 patients.

The researchers envision the hydrogel as part of a subcutaneous system or a sophisticated device that taps into the bloodstream - an insulin pump, for example. However, the application they are most excited about is in short-term continuous monitoring of patients hospitalized or in intensive care units, when patients are most critically in need of continuous monitoring - diabetic or not.

(Read more: A glucose meter that changes colour when sugar levels rise provides continuous monitoring)