Insulin is a hormone made in your pancreas, which is a gland behind the stomach. It helps your body use glucose (sugar) for energy.
When your pancreas is working properly it makes small amounts of insulin all the time and releases more insulin when your blood glucose levels increase after eating. When you have diabetes, your body does not make enough insulin or the insulin it makes does not work properly.
Everyone with type 1 diabetes, and some people with type 2 diabetes or gestational diabetes, needs to take insulin to help manage their blood glucose levels. This reduces the chances of getting the symptoms of high blood glucose (hyperglycaemia) and serious long-term problems that can damage the heart, kidneys, eyes, nerves and feet.
Biphasic insulin is a mixture of short-acting or rapid-acting insulin and intermediate-acting insulin. You usually take it twice a day, about half an hour before breakfast and your evening meal.
The short-acting or rapid-acting insulin helps stop your blood glucose from going too high when you eat carbohydrates, and the intermediate-acting insulin provides low levels of insulin in your body all the time. This is why it's called biphasic insulin.
Some people take biphasic insulin along with other diabetes medicines to manage their blood glucose levels.
Biphasic insulin is available on prescription only. Depending on which brand you use it comes as a pre-filled pen, cartridges that you use in a reusable insulin pen, or a small bottle (a vial) to use with a syringe.
Biphasic insulin types, brands and pens
There are 3 different types of biphasic insulin:
- biphasic insulin aspart (NovoMix 30)
- biphasic insulin lispro (Humalog Mix 25 and Humalog Mix 50)
- biphasic isophane insulin (Humulin M3)
They come in different brands and are used with different types of insulin pen, but they all work in a similar way.
Key facts
- Biphasic insulin starts to work within 30 minutes and lasts for up to 24 hours. You'll usually take it twice a day, before breakfast and your evening meal.
- Your doctor or diabetes nurse will tell you how much biphasic insulin to take.
- Insulin treats the symptoms of diabetes by lowering your blood glucose. But it can sometimes cause your blood glucose to go too low. This is known as hypoglycaemia, or hypos. Make sure you know the symptoms of a hypo, and always carry a source of glucose with you, such as sugary sweets, in case you need to treat a hypo.
- It's a good idea to carry medical identification such as an insulin safety card or insulin passport – a small card with up-to-date details of the type of insulin you use, and what to do in an emergency.
- If you have diabetes, you're entitled to free prescriptions for all your medicines, not just your insulin.