Results from the Diabetes Care and Complications Trial show that tight blood glucose control significantly reduces the long-term complications of diabetes mellitus. In that study, frequent self-testing of glucose and insulin administration resulted in a significant reduction in long-term complications. This protocol, however, also resulted in a threefold increase in the frequency of hypoglycaemic incidents. Currently, self-testing requires a drop of blood for each measurement. The pain and inconvenience of self-testing, along with the fear and danger of hypoglycaemia has led to poor patient acceptance of a tight control regimen, despite the clear long-term advantages. A continuously worn, noninvasive method to periodically measure glucose would provide a convenient and comfortable means of frequent self-testing. A continuously worn device could also alert the user of low glucose levels, thereby reducing the incidence of hypoglycaemia. Guy et al. demonstrated a noninvasive method to transport glucose through the skin using low-level electrical current. To provide a quantitative measurement, the flux of glucose extracted across the skin must correlate with serum glucose in a predictive manner. The results presented here show a quantitative relationship between serum and transdermally extracted glucose in diabetics.