A novel microneedle patch to reliably monitor blood-sugar levels may soon offer diabetics a pain-free alternative to pricking their fingers several times a day to take a blood test, scientists say.

The prototype, designed by researchers at KTH Royal Institute of Technology in Sweden, was successfully tested on a human subject, and completion of the system for clinical tests is now underway.

Continuous monitoring is a way to safely and reliably lower blood glucose -- giving the user a full picture of their glucose levels throughout the day and helping them avoid severe hypoglycemia.

However, the continuous glucose monitoring systems (known as CGMS) in use  are uncomfortable, since they require a minimum 7mm needle inserted into the skin.

Due to their size, they take measurements in the fat tissue -- not the most ideal location.

The newly developed microneedle patch that is 50 times smaller than the needles used in today's CGM systems, researchers said.

The combination of the patch and an extremely miniaturised three-electrode enzymatic sensor was shown in a recent study to be capable of correctly and dynamically tracking blood glucose levels over time, with a delay of about 10 minutes, when applied to a human subject's forearm.

One of the researchers, doctoral student Federico Ribet, said the next steps are to develop a transferable adhesive patch, along with algorithms and embedded electronics for a fully-realised system to take to clinical trial.

"Our solution is painless to the user. We measure directly in the skin, and there are no nerve receptors that detect pain -- just a fine mesh of very tiny blood vessels," said Ribet.

Within the dermis, the hollow microneedles rely on natural capillary action to fill up with interstitial fluid, the liquid surrounding the cells in the skin. Nutrients like sugar, diffuse out of the blood capillaries in this fluid to reach the cells.

"An important distinction is that unlike commercially available CGMS which measure the subcutaneous fat tissue, ours measures within the skin less than 1mm deep, where the interstitial fluid follows closer and more homogeneously the blood-glucose oscillations," he said.

This would offer an alternative to pricking one's fingers several times a day to take a blood test, although a user would still occasionally have to do so in order to recalibrate the sensor and get the most accurate and immediate readings.