Insulin is a hormone that is produced by your body to break down glucose (sugar) from the food you eat so it can be used for energy.
Glucose is found in foods that contain carbohydrates, such as bread, pasta, rice, fruit, legumes, milk, yoghurt and potatoes, as well as in sugary sweets and drinks.
If you have diabetes, your body can’t properly break down the glucose in your body and turn it into energy.
Insulin must be stored correctly to work properly. It can be kept at room temperature (below 25 degrees Celsius) for a maximum of one month. Spare insulin should always be kept in the fridge. Never put insulin in the freezer.
Your doctor or diabetes nurse or educator will have given you advice about taking insulin. It is important that you always follow this advice exactly.
Contact your diabetes nurse or educator if you:
- have forgotten or missed a dose of insulin
- are late taking your insulin
- have not taken enough insulin
If you take too much insulin
Taking too much insulin or other diabetes medicines can cause your blood sugar level to drop too low. This is known as ‘hypoglycaemia’ or a ‘hypo’, and can develop into a serious situation if not addressed. If you think you have taken too much insulin, check your blood glucose level as soon as possible, and repeat this frequently.
If your blood glucose level is low, you will need to address this straight away — see hypoglycaemia for how to do this.
If you take too little insulin
Taking too little insulin can cause your blood glucose level to rise too high. This is called hyperglycaemia.
If you have forgotten or missed a dose of insulin, or not taken enough insulin:
- Do not take the missed dose or extra insulin unless your diabetes nurse or educator or doctor advises you to do so.
- Drink plenty of sugar-free, non-alcoholic fluids such as water to stay well hydrated. Avoid alcohol and drinks containing caffeine, such as cola, tea and coffee because these can dehydrate you.
- Continue to monitor your blood glucose level regularly.
- If you find your blood glucose level remains high, you will need to address this — see hyperglycaemia.
If you run out of insulin
It is a good idea to always keep at least one spare vial of insulin for emergencies, and to take your insulin with you when you go out.
If you run out of insulin:
- Contact your doctor or diabetes nurse or educator for advice.
- Ask your pharmacist if they are able to give you an emergency supply (they may charge for this service).
- You can also search for local services and agencies that can offer confidential advice in the National Health Services Directory.
If your insulin is out of date
All insulin has an expiry date printed on the packet. If this date has been and gone, the insulin is out of date and should not be used. Instead, it should be returned to the pharmacy for safe disposal.
If you have noticed your insulin is out of date and you don’t have any spare insulin to use, see ‘If you run out of insulin’, above.
For more information, read about insulin devices.
Learn more here about the development and quality assurance of healthdirect content.
Last reviewed: July 2020