Insulin lowers blood glucose by stimulating the uptake of glucose into your muscles and fat and stops the liver from producing and releasing more glucose into the bloodstream.

Insulin is the first-line treatment for people diagnosed with Type 1 diabetes as pancreatic destruction means they don’t produce their own insulin. 

People with Type 2 diabetes or gestational diabetes who don’t achieve good glucose control on oral agents will also need to be initiated on insulin. Often people starting insulin feel that they’ve failed in their efforts to manage their diabetes with exercise and diet. Starting insulin isn’t a reflection on discipline or perseverance. Often insulin is the only therapy that can control blood glucose and improve management. It shouldn’t be seen as a last resort or as a punishment.

Types of insulin:

  • Basal or long-acting insulin is usually taken once a day and provides insulin coverage over 18 to 24 hours.
  • Bolus or rapid-acting insulin is taken before meals to prevent a spike in blood glucose from food. An additional amount (correction dose) may be added to lower an already high blood glucose. This usually reduces high blood glucose quickly and will remain in your body for three to five hours.
  • Mixed insulin is a mix of long-acting and rapid-acting insulin. It’s usually taken twice a day before breakfast and dinner and has eight to 12 hours of coverage in your body. The initial amount of insulin will be faster-acting with smaller amounts in your body after five hours. 

Your doctor will discuss which option would be preferable depending on the features of your diabetes. It’s ideal to also see a diabetes educator and dietitian when you start insulin. The diabetes educator will provide education about how to use insulin and help to make any necessary adjustments. The dietitian will discuss the best strategies for eating.

Side effects

The most common side effect is hypoglycaemia (blood glucose level < 4mmol/L). People using insulin should always carry a fast-acting carbohydrate with them, such as sweets or juice, as well as a blood glucose kit. Patients requiring high doses of insulin can also experience weight gain. Adjusting carbohydrate intake can assist with this.

Tips for effective use

  1. The insulin pen in current use can be kept at room temperature while all spare insulin is stored in the fridge. Using a cooler box or gel pack is useful if insulin has to be kept in the car.
  2. Speak to your doctor about using insulin cartridges instead of disposable pens as these are often cheaper and fully reimbursed by medical aids.
  3. Looking after injections sites is vital which involves changing the needle after every third injection and using different sites each time.
  4. When initiating insulin, your dose may need several changes so keep in close touch with your doctor or diabetes nurse. One dosage change every few months isn’t adequate.

Optimal control with insulin is dependent on your individual requirements which is assessed by checking your blood glucose regularly. 

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