At the Center for Nanoparticles Research at IBS, South Korea, a team of researchers have created a patch based on graphene that can sense the level of sugar in the blood by measuring it in the sweat, so without having to prick the skin to get a direct measure on a droplet of blood.
Additionally, the same patch can release artificial insulin to control the amount of sugar in the blood, something that the pancreas is doing when it is working nicely. In many persons the pancreas fail, to greater or lesser extent, hence diabetes steps in.
According to WHO the number of people affected by diabetes is over 400 million (422 million in 2014) and this number is growing (possibly a result of better diagnoses...) leading to blindness, kidney failures, heart attacks, strokes ... hence people misery and growing health care bills.
To control the level of sugar in the blood patients have to follow a diet and monitor the blood glucose and inject insulin one or more times a day. This is clearly unpleasant, to say the least - nobody likes to prick oneself...-, and over long periods is not sufficient since there is no continuous regulation of the blood glucose and the imbalance leads to the aforementioned side-effects/pathologies.
This is why the patch developed in South Korea is so interesting. It provides a continuous monitoring and it can release the right amount of insulin to keep the blood glucose in the correct range. And without pricking...
Actually a bit of pricking occurs but it is done with micro-needles to release the insulin. However they are so tiny that are not perceived by the patient. The glucose monitoring does not require any pricking since it is performed by analysing the sweating of the skin over a 15' period. That period provide a statistically meaningful measurement that researchers have shown is au pair with the usual measurement made on a blood droplet.
The sensing occurs through a hybrid gold graphene layer and a serpentine shape gold mesh that detects temperature, Ph and glucose concentration. A microcomputer on the patch analyses the data over a 15' period and determines if and how much insulin has to be released. Additionally it controls the effect of insulin and adjust the dose accordingly. The powering of the patch is made through an external power supply. I guess one can imagine some sort of "recharging" so that one is no longer constrained by being tethered to the power supply when doing the measurement.