Insulin is a hormone made by the pancreas. It helps the body control the rise in blood sugars that happens when you digest carbohydrates.

Carbohydrates like starch (from rice, pasta, bread and potatoes) or sugars from sweeter tasting foods get broken down into a simple sugar called glucose. Insulin lowers blood glucose levels by helping to move glucose out of the blood and into different organs in the body.

In people with type 2 diabetes, the pancreas does not make as much insulin as it needs to get the blood glucose levels down to healthy levels or the insulin it makes does not work on organs because they are resistant to it.

Who needs to take insulin?

When people are first diagnosed with type 2 diabetes, it may be possible to use medication to help the pancreas make more insulin, or reduce insulin resistance and make the hormone more effective. However, the amount of insulin produced by the pancreas does tend to reduce over time, and eventually the pancreas may not be able to make enough effective insulin to keep blood glucose levels under control, even with extra help from medication.

At this point, using insulin injections will help your body get control of your blood glucose levels and keep them at safe levels.

What are the benefits of insulin?

Insulin is the most effective way of lowering blood glucose levels. There are many different types of insulin that can be used and they will work even if 2 or three other types of glucose lowering medicines won’t.

What are the risks of insulin?

Insulin is a very effective and very important tool in blood glucose control. However it does require regular injections between 1 to 3 times a day. And because it is so effective at lowering blood glucose levels, it can cause very low blood glucose levels (hypoglycaemia) if there is an imbalance between insulin levels and carbohydrate intake.

The DVLA must be informed if you are taking insulin and there are special guidelines for driving safely if you take insulin.

What types of insulin are there?

There are 3 main types of insulin medication that work in different ways - short-acting, intermediate and long-acting insulin.

Short or rapid acting insulins start working very quickly - usually within 15 minutes. They don’t last very long (3-4 hours) and need to be taken with meals.

Intermediate insulins are slower to kick in - they take over an hour to start working and keep working for 12 hours or more. They are usually taken twice a day, often in combination with a rapid-acting insulin that will get to work straight away.

Long acting insulins only need to be taken once a day. After a few days of regular use, they provide a constant level of insulin action. This is very convenient, but they cannot respond precisely to the sudden changes in blood glucose levels that happen after eating.

How is insulin given?

Insulin has to be injected into the body as it gets broken down and digested in the stomach. Injections can be administered through insulin pens, syringes or an insulin pump (mainly used in type 1 diabetes).

Where does injectable insulin come from?

The insulin used to treat diabetes is made by bacteria that have the human gene for insulin. This means that the insulin does not have to come from animals or animal products. It also means that the insulin can be modified to work in different ways and we can make slow or fast acting insulins.

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Reviewed by Dr. Kingshuk Pal