Researchers have developed a new type of glucose-sensing patch, which is worn on the skin and delivers insulin in response to sensing high levels of glucose.
The study showed that the patch was capable of reducing blood glucose levels to normal in mice with chemically induced diabetes over about four hours.
This research is at an early stage, so we therefore don't know if it will be both safe and effective in humans. Before any human testing can occur, researchers will need to study the longer-term effects on animals. Researchers will also need to work out whether they can deliver enough insulin to regulate blood glucose levels in humans, and how often the patches need to be changed.
All in all, we wouldn’t expect to see these patches at your local chemist in the near future.
Where did the story come from?
The study was carried out by researchers from the University of North Carolina and North Carolina State University. It was funded by the American Diabetes Association, and the North Carolina Translational and Clinical Sciences Institute, which is supported by the National Institutes of Health.
The study was published in the peer-reviewed scientific journal Proceedings of the National Academy of Sciences (PNAS).
The UK media’s reporting of the study was patchy. The Mirror fails to mention that the study involved mice, rather than humans. This fact was acknowledged by The Daily Telegraph, though its headline “End in sight for diabetes injections as scientists develop smart patch” is premature, considering the early stage of the research.
What kind of research was this?
This was laboratory and animal research testing a new “smart insulin patch”. It is placed on the skin, and aims to sense blood glucose levels and release insulin accordingly. It could eventually be used to control blood sugar levels in people with diabetes who normally inject insulin, and potentially give better glucose control than the injections. It could enable glucose levels to be monitored constantly, avoiding the need for people to inject themselves, and reduce the chance of errors in the amount of insulin delivered.
Currently, there are mechanical devices that can sense blood glucose and inject insulin into the bloodstream in response. The new system relies on different (chemical) methods to detect glucose levels and deliver insulin, and is smaller than the mechanical devices.
Animal research is an important part of early testing, to make sure things are safe and effective enough to undergo human testing.
What did the research involve?
The researchers first developed and tested their “smart insulin patch” technology in the lab. They then used the patch on mice with a chemically induced form of diabetes. They looked at how well the patch was able to control blood glucose levels in these mice.
The patches were in silicone molds, and had many tiny “micro-needles” on one surface, to project into the skin. The needles contain even smaller packets, called “glucose responsive vesicles” (GRVs). These GRVs contain insulin, and burst and release this insulin into the skin when a high concentration of glucose is detected.
The GRVs contain a protein that binds to glucose and attaches it to oxygen molecules. This causes levels of oxygen in the area around the vesicle to reduce. The molecules that make up the outer surface of the vesicles are sensitive to low oxygen levels, and break down, causing release of the insulin. This all happens rapidly, allowing the insulin to act swiftly to increase the uptake of glucose from the blood by cells.
The researchers developed these GRVs and tested them in the lab first to make sure they did not just release insulin spontaneously. They also tested what happened when they were exposed to solutions with different concentrations of glucose in the lab. They then made micro-needle patches containing the GRVs. The patch itself was made out of a material called hyaluronic acid, which is naturally found in the human body, and the GRVs were chemically attached to it. They researchers tested the response of the patch to solutions with different concentrations of glucose in the lab.
Finally, they tested the patches on mice with chemically induced diabetes. They tested patches with and without GRVs. They also tested GRVs with and without the glucose-sensing protein. The patches were designed to deliver 10 milligrams of insulin per kilogram in body weight.
What were the basic results?
The researchers were able to make GRVs successfully. These GRVs released insulin in response to high glucose concentrations in the lab, even once they were placed in the micro-needles.
The micro-needles on the patches successfully entered the skin of mice with diabetes. The tiny holes left in the skin by the micro-needles closed up within six hours of the patch being removed. The blood glucose levels in mice with the GRV-loaded patches reduced to normal levels after about 30 minutes. They stayed this way for four hours, and then gradually increased again. If the GRVs were missing the glucose-sensing protein, blood glucose levels did not change noticeably.
If the mice were injected with glucose, the mice with the patches showed better “glucose tolerance” than those without the patches. This meant that their blood glucose levels rose more slowly and returned to normal within 30 minutes.
The mice did not show any adverse reactions to the patches or the GRVs.
How did the researchers interpret the results?
The researchers concluded that this was the first demonstration of a man-made glucose-responsive device using low levels of oxygen as a trigger for regulating insulin release. They say that if this technology is developed for human use, its fast responsiveness could help to avoid blood glucose levels getting too high (hyperglycaemia) or too low (hypoglycaemia).
Conclusion
This laboratory and animal study has developed a new type of glucose-sensing patch. This patch is worn on the skin and delivers insulin in response to sensing high levels of glucose. The study showed that the patch was capable of reducing blood glucose levels in mice with chemically induced diabetes.
This research is at an early stage and as yet, we don’t know how well it works in humans. For example, humans are much bigger than mice, and researchers will need to work out whether they can deliver enough insulin to regulate blood glucose levels in humans. They will also need to see how long such patches could regulate blood glucose levels for. Although people might prefer patches to injections, they might not want to change them frequently. Researchers will need to look at the long-term effects of wearing these patches in animals, to make sure they are safe and effective enough before testing them on humans.
There is a lot of work going on in the field of diabetes research, looking at developing alternatives to insulin injections. This study has developed another possible approach, and research will likely continue on these patches and other alternatives.