Insulin is a small but vital protein molecule whose name might be familiar to anyone who has dealt with diabetes, either in humans or animals. It is usually produced by an organ called the pancreas that nestles close to the stomach within the abdomen. Insulin is released by the pancreas mainly when an animal eats. Eating food makes the levels of sugar in the blood increase. So, in response, insulin is released to help transport the sugar from the bloodstream into organs that need it, such as the brain and muscles.
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Diabetes mellitus in animals and people
Diabetic animals and humans either don’t produce insulin (Type 1 diabetes) or the body can’t use it in the normal way (Type 2 diabetes). The result is lots of glucose in the blood, but none for the organs of the body to use. Animals affected by diabetes generally become very thirsty and urinate more. They may lose weight, often despite an increased appetite, and suffer more frequent infections. Left untreated, more severe complications will develop. Diabetic animals may start to show signs such as lethargy, a reduced appetite, sweet smelling breath and eventually collapse. This is often fatal without urgent treatment.
Before insulin was discovered animals, including humans, who suffered from diabetes generally died from their condition in a relatively short time. In 1889 it was discovered that the pancreas produced a substance that if lacking would lead to Diabetes, this was later termed Insulin. In 1921 a young surgeon named Frederick Banting and his assistant Charles Best discovered that they could extract insulin from a dog’s pancreas and used it to successfully treat another dog with severe diabetes. They went on to win the Nobel prize in Medicine in 1923. Initially all insulin in use was extracted from pigs and cows. It was purified and used to treat diabetes in humans and animals. Later DNA technology was used to synthesise “human” insulin. Both types are used successfully to treat diabetes in cats and dogs.
Using insulin
Insulin is a very delicate molecule and needs to be handled carefully. Vials of insulin usually need to be kept in a fridge. Shaking a bottle of insulin risks breaking up the delicate insulin crystals, rendering them ineffective. It can only be given by injection. Taking it by mouth as a tablet or liquid would result in it being quickly broken down by the acids and enzymes in the stomach, rendering it ineffective. Therefore insulin always needs to be given by injection in order for it to work.
The dose of insulin that a pet will need varies from one individual to another
If your cat or dog is diagnosed with diabetes, your vet will recommend a low starting dose of insulin that is given by injection once or twice a day. Injecting your pet can sound daunting at first but most pet owners find, with a little practice, they soon become confident. Many cat owners comment they would rather give an injection than try and get a tablet into their uncooperative cat! Diabetic pets need close monitoring and their insulin dose will often need to be adjusted. So it’s really important to take them for regular check ups with your vet.
Insulin is a powerful medication and it is vital that it is only used under veterinary supervision
The main risk when using insulin is that if too much is given then blood sugar levels can fall dangerously low; a condition that can be life threatening if it is not detected and treated promptly.
The discovery of insulin changed diabetes in humans and animals from a death sentence to a chronic disease that could be successfully managed
Thankfully, it works just as well in our pets as it does in human patients. Exciting developments continue and include insulins that only need injecting once a week instead of every day; continuous glucose monitors which reduce the need for frequent vet trips; an artificial pancreas that responds directly to changes in blood sugar with insulin doses; and new oral treatments for diabetes in cats – all of which could revolutionise the treatment of diabetes all over again.
Further reading:
- Update on insulin treatment for dogs and cats: insulin dosing pens and more – PMC
- Insulins for the long term management of diabetes mellitus in dogs: a review – Canine Medicine and Genetics
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