How Insulin Works: Types of Insulin & Dosage | Cornerstones4Care®

Your Insulin Options

With type 1 diabetes, the beta cells in the pancreas, which make insulin, are destroyed by the immune system. People with type 1 diabetes need to take insulin to control their blood sugar. The amount of insulin taken must be balanced with how much food they eat and how active they are. 

In type 2 diabetes, your body does not produce enough insulin or the cells do not respond to insulin the way that they should, also called insulin resistance. After several years, as your diabetes changes, you may need to take medication to help you manage your blood sugar.

Today, there are many insulin medicines and devices available to treat type 2 diabetes. You and your health care provider can work together to find the insulin medicines that are right for you.


How insulin works

When you inject insulin into your body, your blood sugar level goes down. It goes down because of the way insulin works:

  • Insulin works like a key, unlocking the doors of the cells in your body
  • Once the cell doors open, sugar is able to move from the blood into the cells, where it belongs
  • Once inside the cells, sugar provides energy to the body

Insulin timing

Different insulin medicines work in different ways to replace the insulin you’re missing. They are grouped together based on:

  • When they start to work (onset of action)
  • When they have the greatest effect on blood sugar (time of peak action)
  • How long they work (duration of action)

Ways to describe insulin medicine

Human insulin

Human insulin does not come directly from people. It is made in laboratories. This type of insulin is called "human" because the hormone made in the lab is identical to the insulin your body makes.

Human insulin is available in 3 types:

  1. Short-acting. This insulin, also called regular insulin, is usually taken 30 minutes before a meal and lasts 5 to 8 hours
  2. Intermediate-acting. This type of human insulin, also called NPH insulin, is taken 30 minutes before breakfast, before the evening meal, or at bedtime, and is effective for anywhere from 12-18 hours
  3. Premixed. This type of human insulin includes both a regular insulin and an intermediate-acting insulin. It is taken 30 minutes before breakfast and/or the evening meal and works for anywhere from 12-18 hours   

Insulin analogs

Insulin analogs are human insulin with small changes made to the hormone so that it is absorbed faster or lasts longer in the body.

The 3 main types of analog insulin are:

  1. Long-Acting. Also called basal insulin, this type is not taken with food. It works slowly and lasts longer to control blood sugar between meals and when you sleep
  2. Fast-Acting. Also called bolus insulin. Depending on the medication, this type of insulin may be dosed just before a meal, at mealtime, or shortly after starting a meal.
  3. Premixed. This type is a mixture of fast-acting and intermediate-acting insulins. It works to control blood sugar at mealtime and works for anywhere from 16 to 24 hours

Each type of insulin helps manage blood sugar. But no one type is right for everyone. Each person’s insulin need is different. And each person’s insulin need may change over time. Your health care provider will prescribe the insulin that is best for you.


Although insulin is a hormone that the body makes naturally, injecting it may cause some side effects. Here are a few to be aware of:

Redness, swelling, or itching at the place where you inject. If this reaction happens, let your diabetes care team know. Changing to a different kind of insulin may solve the problem.

Low blood sugar. You may get low blood sugar if you take too much insulin, don’t eat enough, or are more active than usual. When your blood sugar gets too low, you may feel:

  • Weak or tired
  • Hungry
  • Dizzy or shaky
  • Nervous or upset
  • Sweaty
  • Confused
  • Like your mood is changing
  • Like your head hurts

Some people may not have any signs of low blood sugar before they have a problem. This is another reason why regular blood sugar checks are important.

Have you signed up for the Diabetes Health Coach?