Insulin is used to treat diabetes. Find out how to take it safely and possible side effects.

On this page you will find information on:

Types of insulin

There are different brands of insulin available in New Zealand and these are grouped by the time it takes for the insulin to work.

Type of insulin
Rapid-acting insulin
  • Usually works straight away, so it is injected just before or with food.
  • Its effect lasts 1–2 hours.
  • Examples: NovoRapid, Apidra, Apidra Solostar, Humalog
Short-acting insulin
  • Usually works within 15–20 minutes, so inject each dose 15–20 minutes before you eat.
  • Its effect lasts 3–4 hours.
  • Examples: Actrapid, Humulin R
Intermediate and long-acting insulin
  • Usually works after about 1 hour.
  • Its effect lasts all day and may be injected once or twice a day.
  • Examples: Protaphane, Humulin NPH, Lantus, Lantus Solostar
Premixed insulin
  • These insulins are a mixture of short and intermediate-acting insulins.
  • These may be injected 2 or 3 times a day, in the morning, before breakfast and before dinner. Premixed insulin must be injected before dinner, rather than before bedtime. 
  • Examples:
    • NovoMix 30 FlexPen
    • PenMix 30, PenMix 40, PenMix 50 
    • Humulin 30/70 
    • Mixtard 30
    • Humalog Mix 25, Humalog Mix 50

Read more about insulin pens and needles and insulin syringes and needles.

Insulin dose and timing

Your doctor or nurse will work with you to find the best insulin to meet your needs. This can be made up of a rapid-acting insulin and an intermediate or long-acting insulin, or it can be insulin and tablets.  

The timing of your insulin in relation to food and exercise is important. Your doctor or nurse will advise you when it's best to use your insulin. It's best to avoid hot showers or baths within 30 minutes of an insulin dose. Your doctor or nurse will advise what to do if you miss a dose of insulin.

Choosing an injection site

Insulin should be injected into the fatty tissue under your skin. Commonly used sites are the tummy area, thighs and buttocks – the tummy area is the preferred one. You need to move injection sites so that your skin does not become lumpy. Lumpy skin can affect how your body absorbs insulin. Also do not inject insulin on any scar tissue. Read more about insulin injection sites

Drinking alcohol 

Drinking alcohol can affect blood glucose and the dose of insulin may need to be changed. Avoid or limit alcohol intake. Do not drink alcohol on an empty stomach. Eat before or while you are drinking alcohol. Read more about diabetes and alcohol.

If you are unwell and not eating 

If you are unwell, such as throwing up (vomiting) or have runny poos (diarrhoea), and not eating as you usually do, your insulin dose may need to be changed. Contact your doctor or nurse for advice. Read more about diabetes sick day plan

How to store insulin

It is very important that insulin is stored correctly. Incorrectly stored insulin can stop it from working properly.

  • Unopened insulin can be stored in the fridge until it is used. 
  • Do not store insulin in the freezer. 
  • Once opened, insulin vials, cartridges or pre-filled pens can be kept at room temperature but must be discarded after 4 weeks .
  • When keeping insulin in use at room temperature, ensure it is not exposed to sunlight. 

Read more about storing and handling insulin.

What are the side effects of insulin?

  • Lumpiness at the site of injection: You may notice fatty lumps on the surface of your skin at the injection site. Change the injection site and contact your doctor or nurse if you notice pain or redness.
  • Low blood sugar: Sometimes insulin may lower your blood sugar too much – called hypoglycaemia. This may cause you to feel weak, faint, dizzy, drowsy or irritable. You may get a headache, tremor (shakes) or blurred vision. If this occurs, drink something sweet such as a small glass of sweetened soft drink or fruit juice, or lollies. Make sure your family and friends know what to do too. Tell your doctor or nurse if this happens a lot. Your dose of insulin may need to be changed.

Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product

Learn more

New Zealand Formulary Patient Information:

Additional resources for healthcare professionals

Insulin NZ Formulary
Understanding the role of insulin in the management of type 1 diabetes BPAC, NZ, 2019
Insulin in type 2 diabetes – starting and ongoing management Auckland Regional HealthPathways, NZ, 2018
Reducing harm from high-risk medicines - insulin HQSC, NZ
Insulin administration and monitoring HQSC, NZ
Insulin dispensing in community pharmacies HQSC, NZ
Insulin medicine management HQSC, NZ
Insulin prescribing HQSC, NZ

Credits: Sandra Ponen, Pharmacist. Reviewed By: Terrie Spedding, Diabetes Clinical Nurse Specialist, Health Hawke’s Bay – Te Oranga Hawke’s Bay Last reviewed: 30 Jan 2020