Insulin therapy replaces the insulin the body would normally make. People with type 1 diabetes must take insulin every day.
People with type 2 diabetes need to take insulin when other treatments and medicines fail to control blood sugar levels.
Insulin doses are given in two main ways:
- Basal dose – provides a steady amount of insulin delivered all day and night. This helps maintain blood glucose levels by controlling how much glucose the liver releases.
- Bolus dose – provides a dose of insulin at meals to help move absorbed sugar from the blood into muscle and fat. Bolus doses can also help correct blood sugar when it gets too high. Bolus doses are also called nutritional or meal-time doses.
There are several types of insulin available. Insulin types are based on the following factors:
- Onset – how quickly it starts working after injection
- Peak – time when the dose is the strongest and most effective
- Duration – total time the insulin dose stays in the bloodstream and lowers blood sugar
Below are the different types of insulin:
- Rapid-acting or fast-acting insulin starts working within 15 minutes, peaks in 1 hour, and lasts for 4 hours. It is taken right before or just after meals and snacks. It is often used with longer-acting insulin.
- Regular or short-acting insulin reaches the bloodstream 30 minutes after use, peaks within 2 to 3 hours, and lasts 3 to 6 hours. This is taken a half-hour before meals and snacks. It is often used with longer-acting insulin.
- Intermediate-acting or basal insulin starts working within 2 to 4 hours, peaks in 4 to 12 hours, and lasts 12 to 18 hours. This is taken mostly either twice a day or at bedtime.
- Long-acting insulin starts to work a few hours after injection and works for about 24 hours, sometimes longer. It helps control glucose throughout the day. It is often combined with rapid- or short-acting insulin as needed.
- Premixed or mixed insulin is a combination of 2 different types of insulin. It has both a basal and bolus dose to control glucose after meals and throughout the day.
- Inhaled insulin is a rapid-acting breathable insulin powder which starts working within 15 minutes of use. It is used just before meals.
One or more types of insulin may be used together to help control your blood sugar. You also may use insulin along with other diabetes medicines. Your health care provider will work with you to find the right combination of medications for you.
Your provider will tell when and how often you need to take insulin. Your dosing schedule may depend on:
- Your weight
- Type of insulin you take
- How much and what you eat
- Level of physical activity
- Your blood sugar level
- Other health conditions
Your provider can calculate the insulin dose for you. Your provider will also tell you how and when to check your blood sugar and time your doses during the day and night.