Insulin is a hormone made by beta cells in the pancreas. When we eat, insulin is released into the blood stream where it helps to move glucose from the food we have eaten into cells to be used as energy. In people with type 1 diabetes, the body produces little or no insulin as the cells that produce insulin have been destroyed by an autoimmune reaction in the body. Insulin replacement is required by daily injections.

At this stage, insulin can only be injected. Insulin cannot be given in tablet form as it would be destroyed in the stomach, meaning it would not be available to convert glucose into energy.

Administering Insulin

Insulin is injected through the skin into the fatty tissue known as the subcutaneous layer. You do not inject it into muscle or directly into the blood. Absorption of insulin varies depending on the part of the body into which you inject. The tummy (abdomen) absorbs insulin the fastest and is the site used by most people. The buttocks and thighs are also used by some people.

While it is essential to give each injection in a slightly different spot within the one site, it is not advisable to change sites without first discussing it with your doctor or Credentialled Diabetes Educator.

The range of injection devices and tiny needles available today make injecting insulin much easier than most people imagine. When starting insulin, your doctor and Credentialled Diabetes Educator will help you adjust to the new routine and task of giving insulin and find the right dose to reduce your blood glucose levels to acceptable levels.

Insulin can be injected by an insulin syringe, an insulin pen with a fine needle, or via an insulin pump. Each method is chosen for a particular purpose and based on an individual’s needs.

Insulin syringes and insulin pens (pen needles) are currently the most common way of administering insulin. Injection devices are made in different sizes, and the size used depends on the quantity of insulin being injected. To avoid under or over dosing, it is important that you know how to measure the insulin dose in your device. Your Credentialled Diabetes Educator can help you with this.

Many people find pen devices easier and more convenient to use than syringes. If you have difficulties with your sight or have problems with arthritis you may find a pen device easier to use.

The insulin pump is a small programmable device that holds a reservoir of insulin. The pump is programmed to deliver insulin into the body through thin plastic tubing known as the infusion set or giving set. The pump is worn outside the body, in a pouch or on your belt. The infusion set has a fine needle or flexible cannula that is inserted just below the skin where it stays in place for two to three days.

Only fast acting insulin is used in the pump. Whenever food is eaten the pump is programmed to deliver a surge of insulin into the body similar to the way the pancreas does in people without diabetes. Between meals a small and steady rate of insulin is delivered.

The insulin pump is not suitable for everyone. If you’re considering using one, you must discuss it first with your doctor or Credentialled Diabetes Educator.

Types of Insulin

When you take insulin it acts to reduce the level of glucose in your blood. When glucose is at its lowest level, the effect of the insulin is said to have reached its 'peak'. After this, the effect gradually wears off and blood glucose levels rise.

Your doctor or Credentialled Diabetes Educator will work out with you what type of insulin is right for you.

  • Fast-acting insulin is clear in appearance, and starts to work from 1 to 20 minutes. It peaks approximately 1 hour later, and lasts from 3 to 5 hours. You must eat immediately after injecting fast-acting insulin.
  • Short-acting insulin is clear in appearance. It begins to work within half an hour, so you need to inject half an hour before eating, and it peaks at 2 to 4 hours and last for 6 to 8 hours.
  • Intermediate-acting insulin is cloudy in appearance, and has either protamine or zinc added to delay its action. It begins to work about 1 and a half hours after injecting, peaks at 4 to 12 hours and lasts for 16 to 24 hours. Before injecting, check the leaflet included in the pack for instructions on preparing the insulin.
  • Mixed insulin is cloudy in appearance and contains pre-mixed combinations of either a fast-acting or a short-acting insulin and an intermediate-acting insulin. This makes injecting easier by giving two types of insulin on one injection. This insulin can be taken before a meal to provide a stable level of insulin for some time after the meal. Before injecting, check the leaflet included in the pack for instructions on preparing the insulin.
  • Long-acting insulin is clear in appearance. It typically has no pronounced peak and lasts for up to 24 hours.
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