More than 8 million people worldwide have diabetes. Researchers are trying to develop ways to replace the function of the pancreas, which releases insulin in order to control the body’s blood sugar level. The current standard practice involves taking measurements from a drop of blood acquired by pricking a fingertip, and then injecting a specific dose of insulin. Errors in dosage can lead to serious complications, including blindness, loss of limbs, coma, and even death. Some scientists have taken the approach of developing wearable sensors that deliver blood sugar measurement data to an insulin pump, which automatically adjusts the amount of insulin administered.

Now a researchers at the University of North Carolina and North Carolina State have created a “smart” insulin patch that may provide a simple solution to the problem. Patches have long been used to deliver medication over time; the nicotine patches used by smokers trying to quit tobacco are a prime example. But the insulin patch is different; it actually detects the blood sugar level and then administers the correct amount of insulin in response. The patch has a matrix of microscopic needles that painlessly pierce the skin of the patient, reaching the blood in the tiny capillaries within the skin. Each needle contains a tiny drop of insulin, but it is blocked from release by a coating of enzymes. These chemicals are sensitive to blood glucose, and release the required amount of insulin automatically. There is no electronic sensor, no batteries, and no data communication required.

The researchers have tested the device successfully on mice, and found that it kept blood glucose levels stable far longer than injected insulin. They believe that the system could be used to create disposable patches that would be worn for days at a time, providing around the clock control of blood sugar levels. This could be far more convenient, reliable, and less expensive than either the current standard treatment or a complex digital system.