Insulin Patch Could Replace Injection in Diabetes Treatment

Diabetic patients have to manage their blood sugar levels by consistently pricking their finger and giving themselves insulin injections. The process is painful and imprecise; injecting the wrong quantity of insulin can result in serious issues, and in certain cases, coma and death.

Image credit: Zhen Gu
Image credit: Zhen Gu

Now, the progression of a “smart insulin patch” could one day make such an ordeal a thing of the past for the millions of people who suffer from this condition. This has been made possible by a team of researchers from the University of North Carolina (UNC) in Chapel Hill.

The smart patch, no bigger than a penny – has over a hundred micro-needles, each about the size of an eye lash that contain tiny reservoirs of insulin and glucose-sensing enzymes.

This patch can be applied anywhere on the body and it automatically discharges the right quantity of insulin into the bloodstream once it has detected high blood sugar levels.

In the proceedings of the National Academy of Sciences, the diabetes physicians and biomedical engineers who developed the pain-free patch explain how they examined it in a mouse model of type 1 diabetes and demonstrated it lowered blood glucose for several hours.

Even though it demonstrates great promise, it is very early to say if and when the patch can be made available to the general public as more comprehensive clinical studies are required.

Patch imitates body’s own system for producing insulin

The smart insulin patch performs by resembling the body’s own system for producing insulin – the beta cells of the pancreas – which generate and keep insulin in tiny sacs or vesicles. They also sense modifications in blood sugar and signal insulin to be produced from the vesicles as required.

The team designed synthetic vesicles that work in a similar way out of two natural materials – hyaluronic acid (HA) used in cosmetics and 2-nitroimidazole (NI), an organic substance used in diagnostics.

Collectively, the two substances form a molecule that is water-loving at one end (the HA part) and water-repellent at the other (the NI part). Groups of the compound self-construct into vesicles – just like oil droplets do in water – with the water resistant ends on the interior and the water-loving ends on the external surface.

The investigators identified they could place a core of solid insulin and enzymes developed to identify glucose into the artificial vesicles, which resulted in formation of millions of bubble-like nanostructures, each 100 times smaller sized than the thickness of human hair.

When they examined the intelligent insulin nanoparticles in the laboratory, the team identified they reacted to increased blood sugar. The unwanted glucose molecules entered the synthetic vesicles, using up oxygen as the enzymes on board transformed them into gluconic acid. This decrease in oxygen or “hypoxia” transforms the water-repellent end from water repellent to water-loving, and the vesicles dissolve and discharge insulin into the blood-stream.

Smart Patch maintained normal blood sugar levels in diabetic mice for hours

The next step for the investigators was to identify a way to provide the artificial vesicles to diabetic patients. This is when they transformed to the concept of tiny micro-needles incorporated into a patch, instead of depending on the huge needles or catheters of the “closed-loop systems” of other methods to glucose-sensitive insulin delivery.

They gradually developed a silicon strip with more than a hundred micro-needles that pierce the skin and tap into the blood circulation in the underlying capillaries. Each micro-needle consists of a reservoir of the synthetic vesicle.

The team examined the novel patch in a mouse model of type 1 diabetes. They provided one group of mice a regular insulin injection – the levels decreased to normal but then rapidly rose to hyperglycemic levels.

But when they applied a different group of diabetic mice with the smart insulin patch, their blood sugar levels stabilized within 30 minutes and remained so for several hours.

The investigators also identified that by varying the dose of the enzyme, they could fine-tune the patch to modify glucose levels within certain ranges.

Mice are less sensitive to insulin than human beings

Mice are less sensitive to insulin than human beings, so the investigators think that the novel patches could last even more time in diabetic patients. The scientists goal is to develop a smart insulin patch that would only require to be changed once every few days.

Such a innovation would be a “game changer” for diabetics, describes co-senior author John Buse:

“The tough part of diabetes care is not the insulin injections, or the blood sugar checks, or the diet plan but the fact that you need to do them all many times a day.”

Co-senior author Zhen Gu, states that:

“We have developed a novel patch for diabetes that works quickly, user friendly, and is made from non-toxic, biocompatible substances. The entire system can be personalized to account for a diabetic’s weight and sensitivity to insulin, so we could make the smart patch even smarter.”