Diabetes affects some 300 million people worldwide and the numbers keep on increasing. Many of these people undergo a daily regimen of tests that measure the amount of glucose in the blood stream, usually taken from finger prick samples.

Needless to say, this is a time-consuming, expensive and painful process. So a cheap way of measuring blood glucose that does not require finger pricking would clearly be advantageous.

Today, Mitchell Lerner at the University of Pennsylvania in Philadelphia, and a few pals, say they have developed just such a device. Their glucose sensor is essentially a carbon nanotube-based transistor in which the never tubes are coated with pyrene-1-boronic acid molecules that bind to glucose.