A needle in a little bottle of insulin against a pink and blue background.
Unlike injectable insulin, inhalable insulin is distributed via an inhaler, passing through the lining of the lungs.

What to Know About Inhalable Insulin

It has been estimated that insulin use will increase by 20% worldwide by the year 2030. Currently, there are approximately 8.3 million people who use insulin to control their blood sugar levels in the U.S. Insulin is a required medication for those with type 1 diabetes. For those with type 2 diabetes, there are a variety of treatment modalities, but insulin is used in approximately 25% of those with diabetes. Did you know there are different types of insulin? For this article, we will be focusing on inhalable insulin.

What is Inhalable Insulin?

Inhalable insulin has been on the market since 2006, when Pfizer’s Exubera was approved by the U.S. Food and Drug Administration (FDA). Unfortunately, it was pulled from the market one year later due to critiques of the bulky device as well as safety concerns. However, Mannkind released Afrezza in 2014. It has been on the market ever since.

Afrezza is a pulmonary delivery form of insulin, meaning that it is inhaled into the lungs with an inhaler device. It is available in several dosage cartridges, allowing for different dose options.

How Does Inhalable Insulin Differ From Injectable Insulin?

The biggest difference between inhalable insulin and injectable insulin is, of course, its method of administration. Afrezza uses an inhaler device, whereas injectable insulin requires the use of an insulin pen and needle or an insulin vial and a syringe.

Aside from the obvious, there are other ways that inhalable insulin differs from injectable insulin. For example, Afrezza works within one minute and peaks about 12 minutes after administration. This is much shorter than rapid-acting insulin, which begins working in about 5 to 15 minutes and peaks about 30 minutes after administration.

During the STAT trial, researchers found that those who used Afrezza were able to stay in range (70mg/dl to 180mg/dl) for longer durations of time – 63% for those using Afrezza, whereas Novolog users were in range 54% of the time. Users also spent less time with critically low blood sugar (defined as less than 50mg/dl for the STAT trial): just three minutes with Afrezza and up to 12 minutes with Novolog.

How Does Inhalable Insulin Work?

Afrezza is inhaled into the lungs using an inhaler. Once it reaches the lungs, the insulin passes through the lining of the lungs, where it passes directly into the bloodstream.

Al Mann, the creator of Afrezza, says, “We’re actually delivering insulin monomers (molecules). Nobody ever did that before. It behaves much like normal pancreatic insulin does. Normal people don’t get hypoglycemia, and people (with type 2 diabetes) taking Afrezza don’t either, even if they dose and don’t eat.”

The Afrezza inhaler, which is replaced every two weeks, is filled with color-coded cartridges:

  • 4 units (blue).
  • 8 units (green).
  • 12 units (yellow).

Dosing can be confusing. Inhaled insulin does not behave like injected insulin; therefore, it is not dosed unit to unit like your usual mealtime or correction insulin.

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When Should Inhalable Insulin Be Used?

Since Afrezza is an ultra-rapid acting insulin, it should be used in instances when a subcutaneous injection of rapid-acting insulin would be indicated. It cannot replace basal insulin dosing.

Afrezza can be used in people with type 1 diabetes and people with type 2 diabetes who require insulin. It is indicated for use as mealtime insulin – when eating carbohydrates – and as correction insulin. However, there are some caveats. Those who require small insulin doses or have low carbohydrate intake may do better with insulin injections or with an insulin pump because the smallest dosing available for Afrezza is 4 units.

Because Afrezza typically is gone from the body in about two hours, users can feel more comfortable correcting their blood sugar more frequently. Those using another rapid-acting insulin typically should not correct their blood sugars more than every three to four hours because it causes insulin stacking, which increases the likelihood of developing hypoglycemia.

It can also be tricky to dose Afrezza for high-fat meals, such as pizza. This is because high-fat meals can cause a delayed spike in blood sugar. You may need to treat this with an injection, or you may need to correct your blood sugar more frequently after these meals.

What Are the Side Effects?

The biggest side effect of Afrezza is coughing. For those with a bothersome cough, Afrezza may make it worse. However, this side effect can typically be mitigated by taking a drink of water just prior to administration.

A word of caution: Afrezza should not be used to treat diabetic ketoacidosis (DKA). You should also refrain from using Afrezza if you have a lung condition, such as COPD or asthma, or are a smoker. You should also discuss using Afrezza with your provider if you have the following health conditions:

  • Lung cancer or have a history of lung cancer.
  • Are pregnant or trying to become pregnant.
  • Have kidney or liver problems.
  • Using any other inhaled medications.