For many people with diabetes, taking insulin without injections sounds highly attractive. Inhaled insulin provides a rapid-acting, needle-free option for managing the rise in blood glucose after meals.
However, inhaled insulin is not a complete replacement for all insulin injections. It acts faster, remains active for a shorter period and requires proper lung-function screening before use.
So, how effective is inhaled insulin, and who can use it safely?
What Is Inhaled Insulin?
Inhaled insulin is a dry-powder form of human insulin that is breathed into the lungs using a small inhaler. It is absorbed through the lungs and enters the bloodstream rapidly.
The best-known inhaled insulin product is Afrezza, which is supplied in single-use cartridges of different strengths. It is intended mainly for controlling glucose levels around mealtimes.
In India, Afrezza has been launched by Cipla for adults with diabetes. Approved age groups and prescribing instructions may vary between countries, so patients should always follow local medical guidance.
How Quickly Does It Work?
Inhaled insulin works faster than many injected rapid-acting insulins.
Its glucose-lowering effect may begin in approximately 12 minutes, peak within about 35 to 55 minutes, and reduce significantly within a few hours, depending on the dose.
It is usually taken at the beginning of a meal. Because it acts quickly, it may help control the sharp rise in glucose that occurs immediately after eating.
Its shorter duration may also reduce the amount of insulin remaining active several hours after a meal. However, the correct dose must be determined by a diabetologist or endocrinologist.
How Effective Is Inhaled Insulin?
Type 1 Diabetes
People with type 1 diabetes require two forms of insulin:
- Basal insulin for background insulin needs.
- Mealtime insulin to manage food-related glucose increases.
Inhaled insulin may replace some mealtime injections, but it cannot replace basal insulin. People with type 1 diabetes must continue using basal insulin through injections, a pump or another approved method.
Clinical studies have shown that inhaled insulin, when combined with basal insulin, can provide effective overall glucose control. However, in some studies, injectable rapid-acting insulin produced a slightly greater reduction in HbA1c.
One adult trial reported an HbA1c reduction of approximately:
- 0.21% with inhaled insulin
- 0.40% with injected insulin aspart
More recent research suggests that inhaled insulin can achieve comparable overall glucose control in carefully selected and well-monitored patients. It may be particularly useful for controlling rapid after-meal glucose spikes.
The results depend heavily on correct dosing, meal composition, glucose monitoring and proper adjustment of basal insulin.
Type 2 Diabetes
Inhaled insulin may also be considered for adults with type 2 diabetes whose glucose remains uncontrolled despite lifestyle changes, oral medicines or other injectable treatments.
In one 24-week study:
- HbA1c fell by approximately 0.82% with inhaled insulin
- HbA1c fell by approximately 0.42% with inhaled placebo
This indicates that inhaled insulin can provide meaningful additional glucose control for selected patients. However, it may not always be the first treatment recommended because several other diabetes medicines may provide glucose control with fewer lung-monitoring requirements.
Potential Benefits
Fewer Mealtime Injections
Inhaled insulin may reduce the number of daily injections. This can be helpful for people with needle anxiety or difficulty taking injections at work, while travelling or in public.
Rapid After-Meal Control
Its fast absorption may match the early glucose rise after meals more closely than some injected insulins.
Shorter Duration
Inhaled insulin generally leaves the bloodstream sooner. This may reduce prolonged insulin activity and delayed low blood glucose in some patients.
Portable and Convenient
The inhaler is small and does not require needles. However, patients must carry the correct cartridges and learn the proper inhalation technique.
Is Inhaled Insulin Safe?
Inhaled insulin can be safe when prescribed to properly selected and monitored patients. It is not suitable for everyone.
Low Blood Glucose
Inhaled insulin is still insulin and can cause hypoglycaemia.
The risk increases when:
- The dose is too high.
- A meal is delayed or skipped.
- Fewer carbohydrates are eaten than expected.
- Physical activity increases.
- Kidney or liver function is reduced.
- Other diabetes medicines are being used.
Patients should know how to identify and treat hypoglycaemia. Regular glucose monitoring, including continuous glucose monitoring where appropriate, can improve safety.
Cough and Throat Irritation
Cough is the most common respiratory side effect. Clinical trials reported cough in approximately 27% of adults using inhaled insulin.
For many people, the cough is mild and may improve with time. However, some patients stop treatment because of persistent coughing or throat irritation.
Reduction in Lung Function
Studies have found a small reduction in lung function among some inhaled insulin users. Lung function is commonly measured using a test called spirometry.
Spirometry should generally be performed:
- Before starting treatment.
- Around six months after starting.
- Every year thereafter.
- Whenever persistent cough, wheezing or breathing difficulty develops.
Treatment may need to be stopped if lung function decreases significantly.
Asthma and COPD
Inhaled insulin should not be used by people with asthma or chronic obstructive pulmonary disease, known as COPD.
It may cause acute narrowing of the airways, known as bronchospasm. A medical history, physical examination and lung-function test are required before treatment.
Smoking
Inhaled insulin is generally not recommended for current smokers or people who have recently stopped smoking.
Smoking may alter how insulin is absorbed through the lungs and make its effect less predictable.
Lung Cancer Concerns
A small number of lung cancer cases were reported during and after clinical trials. The number of cases was too low to prove that inhaled insulin caused the cancers.
People with active lung cancer, a previous history of lung cancer or a high risk of lung cancer require careful medical evaluation before inhaled insulin is considered.
Diabetic Ketoacidosis
In type 1 diabetes studies, diabetic ketoacidosis, or DKA, occurred slightly more frequently with inhaled insulin than with comparator treatments.
People with type 1 diabetes must continue basal insulin and follow proper sick-day rules. During illness, infection, vomiting or rapidly increasing glucose levels, injectable rapid-acting insulin may be required.
Inhaled insulin is not used to treat diabetic ketoacidosis.
Who May Be a Suitable Candidate?
Inhaled insulin may be considered for someone who:
- Requires mealtime insulin.
- Has normal lung function.
- Does not have asthma or COPD.
- Does not smoke.
- Is willing to monitor glucose regularly.
- Can use the inhaler correctly.
- Has significant fear or difficulty with mealtime injections.
- Is under the supervision of an experienced diabetes specialist.
It may not be appropriate for people with chronic lung disease, persistent breathing symptoms, frequent severe hypoglycaemia, poor glucose monitoring or a high risk of diabetic ketoacidosis.
Does It Eliminate Needles Completely?
Not necessarily.
People with type 1 diabetes will normally still require basal insulin through injections, a pump or another approved delivery system. Glucose monitoring is also still essential.
Inhaled insulin should therefore be described as a way to reduce mealtime injections, rather than as a completely needle-free diabetes treatment.
Final Verdict
Inhaled insulin is a clinically useful treatment option for selected people with diabetes. It acts quickly, helps control mealtime glucose and may reduce the burden of multiple daily injections.
However, it is not automatically safer or more effective than injectable insulin. Some patients may achieve slightly better HbA1c reduction with injected rapid-acting insulin.
Its biggest limitation is the need for lung-function screening and monitoring. Cough is common, and it should not be used by people with asthma, COPD or current smoking exposure.
For the right patient, inhaled insulin may improve convenience and quality of life. For someone with lung disease, poor glucose-monitoring habits or a high risk of DKA, it may create unnecessary risks.
The decision should always be made together with a qualified diabetologist or endocrinologist.
Medical Disclaimer
This article is intended for general educational purposes only. It should not be considered medical advice, diagnosis or a personal treatment recommendation.
Insulin is a prescription medicine that can cause severe hypoglycaemia and other serious side effects. Patients should not start, stop or change insulin treatment without consulting a qualified diabetologist or endocrinologist. Product approvals and prescribing requirements may differ between countries.