People with type 1 diabetes – the insulin-dependent version – must take insulin in order to keep their blood sugar down. Currently the most dependable way to do that is with insulin injections. However, recent research indicates that a more convenient way to take insulin may not be far off.
What is insulin?
Insulin is a protein hormone produced by the pancreas. It’s released in response to an increase in blood sugar after a person eats carbohydrates – foods like starches and sugars.
People who have type 1 diabetes produce either too little insulin or, in some cases, no insulin at all. Therefore, they have to get it from an outside source. Insulin’s been available since the 1920s, and scientific research has been able to develop a form that is relatively pure, which makes it stronger and more reliable. Still, the best way to take insulin is via injection.
The problems with insulin injections
Insulin is injected subcutaneously – under the skin. This isn’t a very deep injection; the needles used are short and thin. But it’s still an injection. There can be pain in that area, and some people develop itching or other allergic reactions there.
Also, because there’s no cure for diabetes, the diabetic must take insulin every day – sometimes more than once a day. It would be really harmful to inject insulin, or any drug, into the same place this frequently, so the injection sites must be “rotated.” But over a lifetime of injections, obviously the same sites will be used many times. These sites can develop lipodystrophy, a condition which causes a kind of puckering of the skin and other tissue in that area. It may not be very noticeable, but it does affect how insulin is absorbed from that site. So the site either needs higher doses of insulin – which can be dangerous – or it can no longer be used for injections.
Injections also require the use of sterile technique. This can be taught and is fairly easily learned by some people, but others can’t do it, so their injections must be given by someone else – a family member or caregiver, perhaps.
Add to these problems the inconvenience of the process and its expense – the cost of syringes, for example – and there’s a lot of motivation for researchers to come up with a different way to administer insulin. The most obvious method, of course, is the oral one – tablets, capsules, or possibly liquids.
The problems with oral insulin
You may be wondering why insulin isn’t just taken by mouth. That’s probably what was first tried after insulin was discovered. But physicians soon realized that, at least in this case, it wasn’t as easy as it seemed.
Insulin is a protein. Proteins are foods which are digested by the intestinal tract. The enzymes which break down the proteins in foods (like meats and cheeses) do the same to insulin. As a result, by the time the insulin has passed through the intestinal tract, there’s not much left to be absorbed into the bloodstream. The little that does get absorbed may be further filtered out by the liver.
In order to get a useful amount of insulin into the blood this way, a very high dose must be taken – and that’s dangerous. There’s no good way to predict how much insulin will be absorbed. There might not be enough to bring the blood sugar down at all. Or there might be so much that the blood sugar will go too low.
The promise of research
Scientists have been trying different techniques to get past the absorption problems in the intestinal tract. These techniques include methods to “protect” insulin from being broken down before it can be absorbed and ways to increase its absorption. But scientists have to be careful that whatever system they develop doesn’t affect the way the intestines absorb other substances – like normal foods – and doesn’t damage the intestines in the process.
Research is being conducted worldwide. A hospital in Jerusalem has been working on testing an insulin “pill” developed by a company in the United States. And more recently, a version of insulin that’s been bonded to chitosan – a substance produced from the shells of shellfish like crabs and lobsters – has been successful in lowering the blood sugars of rats in a study conducted in Taiwan.
This research, like all others, needs to be applied to humans before an oral version of insulin will be approved. But it does reflect the hope – and perhaps the probability – that one day diabetics will be able to throw out their syringes and simply take a tablet or capsule in order to control their blood sugar and keep themselves healthy.