New "smart insulin" could allow diabetics to swap out painful injections for an innocuous patch.
The "smart insulin patch" detects increases in blood sugar levels, and secretes insulin directly into the bloodstream whenever it is needed, the University of North Carolina at Chapel Hill reported. The patch is no larger than a penny, and covered in microneedles equipped with microscopic storage units for insulin and glucose-sensing enzymes.
"We have designed a patch for diabetes that works fast, is easy to use, and is made from nontoxic, biocompatible materials," said co-senior author Zhen Gu, a professor in the Joint UNC/NC State Department of Biomedical Engineering. "The whole system can be personalized to account for a diabetic's weight and sensitivity to insulin, so we could make the smart patch even smarter."
Patients with type 1 and advanced type 2 diabetes must keep their blood sugar in check with painful insulin injections, and making mistakes can come with serious consequences.
"Injecting the wrong amount of medication can lead to significant complications like blindness and limb amputations, or even more disastrous consequences such as diabetic comas and death," said John Buse, co-senior author of the PNAS paper and the director of the UNC Diabetes Care Center.
The new device imitates the body's natural insulin generators known as beta cells, which release insulin and behave as "alarm call centers" that sense when blood sugar is too low. It is made from hyaluronic acid (HA), a natural ingredient used in many cosmetics, and the organic compound 2-nitroimidazole (NI). The two substances were combined to create a new molecule that has one "water-loving" end and one "water-fearing" end. These molecules proved to self-assemble into a vesicle with the hydrophobic ends pointing inward and the hydrophilic ends pointing outward. The team inserted a core of solid insulin and glucose-sensing enzymes into each individual vesicle.
In lab experiments, the researchers observed when blood sugar levels increased, the excess glucose moved into the artificial vesicles. The enzymes converted the glucose into gluconic acid, consuming all of the present oxygen. Once the oxygen was depleted the hydrophobic NI molecules turned hydrophilic, causing the vesicle to fall apart and release insulin into the blood stream.
The method was tested in a mouse model of type 1 diabetes, and found blood glucose levels were brought under control in 30 minutes and stayed that way for several hours.
"The hard part of diabetes care is not the insulin shots, or the blood sugar checks, or the diet but the fact that you have to do them all several times a day every day for the rest of your life," Buse said. "If we can get these patches to work in people, it will be a game changer."
