New device for diabetes
People with diabetes cannot make enough of the hormone insulin, which controls blood sugar levels. In type 1 diabetes, the body cannot make any insulin at all, and instead the hormone has to be injected through the skin in varying amounts tailored to mealtimes and what someone is eating. Now scientists in the US have developed a sugar-sensitive molecule that works like an insulin “sponge”, dispensing insulin automatically into the bloodstream whenever blood sugar levels climb. Mark Evans, who’s a diabetes specialist at Addenbrooke’s hospital in Cambridge but wasn’t himself involved in the research, spoke to Chris Smith...
Mark - So this is one of a group of approaches which people refer to as smart insulins. They've taken standard insulin that we already use to treat diabetes and they've combined it with a polymer, so a large molecule a bit like a ball of wool which soaks up the insulin and then can release it.
The particular polymer they've chosen is boronic acid which binds and responds to changes in glucose and sugar levels. So by tinkering about with this they've rather neatly been able to come up with a formulation which means that the polymer is glucose responsive. So in other words this ball of wool is able to react to sugar, change its charge, and release more insulin when it is exactly the time it's needed. In other words, when the local glucose levels are higher. And equally importantly, it's able to release less insulin then when glucose levels are lower.
Chris - At the moment, a person who is diabetic would need to tailor how much insulin they have in their body that they inject, in order to match what they anticipate their meal is going to deliver, or their activity. So this would release them from some of that wouldn't it would mean that the molecule’s doing the work of calculating how much insulin to release, rather than them.
Mark - Absolutely it'll certainly help. The life of somebody with diabetes, particularly let's say with type 1 diabetes, is challenging and they spend their whole time chasing their tail doing lots of blood glucose testing and trying to catch up with ups and downs. And the hope is that something like this will at least help to let's say shave off some of the ups and fill in some of the valleys in daily blood glucose levels.
Chris - What's the evidence this technique actually works?
Mark - So they've tested their system in mice and in pigs with type 1 diabetes under conditions of artificial glucose load. So essentially giving a slug of glucose and delivering either this insulin or regular insulin. They've also in mice done a slightly longer term study over a couple of weeks or so of twice daily injections and does seem to work at least better than the control insulin that they gave under that particular experimental conditions they tested this under.
Chris - How is this new smart insulin actually administered? Is it injected in the same way that traditional insulin that a diabetic is familiar with is given?
Mark - Yes. So they delivered this by injection in these studies. At the moment insulin has to be delivered across the skin of the body in some way shape or form, whether that's by injection or increasingly we've got people treated with insulin pumps which are devices which pump insulin continuously under the skin.
So this new approach would probably substitute in for the existing insulins but it would be delivered in the same way so by injection or infusion under the skin.
Chris - You mentioned that it's the glucose going into this polymer which then causes it to release or squirt out the insulin, so you match how much insulin you produce to how much glucose is there. But could any other molecules accidentally do that? So you could unfortunately trigger a big surge of insulin when you don't need it because something has tripped the molecule into releasing it inappropriately?
Mark - Absolutely, that's a great question and that's one of the questions that arises out of this - how specific is that polymer for glucose as opposed to other non glucose sugars things like fructose and things which occur naturally for example in fruit. So this is all part of the work that they're going to have to do to really try to nail this before they're able to move into human studies.
Chris - And say they can pull it off, what are the implications for a person with diabetes? Because we can we can manage diabetes pretty well in this day and age can't we? You can use pumps, you can use injections to keep people well.
Mark - So the way in which I, as a clinician, I would see this being used is as an alternative to the insulin that people are currently using, but actually used in the same way. And I think what it will do is hopefully help smooth out some of the ups and downs in daily blood glucose levels.
Chris - And that will translate into a health benefit?
Chris - Absolutely. If people get less variable and more predictable blood glucose levels, one we think that the variability in glucose itself may be important in terms of risk of complications but two, if people have got less variability they may be more confident to drive blood glucose levels lower which reduces long term risk of complications.