Insulin overview

Easy-to-read medicine information about insulin – what it is, how to use 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: Protophane, 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

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. When injecting in your tummy area, it should be about 1 cm away from your belly button. When using your thighs, use the top and outer areas only. Do not use the inside or back of your thigh or close to the joints.

Change injection sites regularly

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.

Different injection sites have different absorption rates.

  • It is therefore not advisable to rotate daily from one part of your body to another. Instead rotate within the area being used, eg, you can move from one side of your abdomen to the other side each time.
  • If you are having 2 or more injections a day, choose a morning and afternoon site, eg, morning site, left thigh and afternoon site, right thigh. 
  • When injecting 2 different insulins, inject them in different sites.

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

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

  • Unopened insulin can be stored in the fridge until it is used. Check expiry dates.
  • 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 28 days.
  • When keeping insulin in use at room temperature, ensure it is not exposed to sunlight. 
  • Insulin is destroyed by heat, so don't leave it in a car or anywhere the temperature goes above 40°C. 

Side effects when using 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.

Learn more

New Zealand Formulary Patient Information:

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