What are the drawbacks of using inhaled insulin, such as Afrezza (insulin human), in patients with chronic lung disease, like asthma or chronic obstructive pulmonary disease (COPD)?

Drawbacks of Inhaled Insulin

Inhaled insulin is absolutely contraindicated in patients with chronic lung disease including asthma and COPD, causes decline in lung function (reduced FEV1), requires mandatory spirometry monitoring before and during therapy, is contraindicated in smokers or recent quitters, has limited dosing range, and causes cough in 24-33% of patients. 1

Absolute Contraindications in Lung Disease

• Chronic lung disease including asthma and COPD represents an absolute contraindication to inhaled insulin use. 1
• Active smoking or recent smoking cessation is also an absolute contraindication. 1
• These contraindications are consistent across all major diabetes guidelines and are non-negotiable safety requirements. 2

Pulmonary Function Decline

• Use of inhaled insulin may result in decline in lung function, specifically reduced forced expiratory volume in 1 second (FEV1). 1
• This decline in pulmonary function is a direct adverse effect of the medication on lung tissue. 1

Mandatory Safety Monitoring Requirements

• All patients require spirometry (FEV1) testing to identify potential lung disease prior to starting inhaled insulin therapy. 1
• Periodic spirometry monitoring is required after starting therapy to detect any decline in lung function. 1
• This requirement for ongoing pulmonary function monitoring adds significant complexity to diabetes management compared to injectable insulin. 2

Common Adverse Effects

• Cough is the most common adverse effect, occurring in 24-33% of patients using inhaled insulin versus only 2% with injectable insulin aspart. 3
• Coughing typically occurs shortly after inhalation and is usually mild, but this high incidence can significantly impact treatment adherence. 4, 3

Limited Dosing Range

• Inhaled insulin has a limited dosing range compared to injectable insulin options, which restricts its use in certain patients requiring higher or more flexible dosing. 1, 2
• The medication requires approximately twice the dose of rapid-acting insulin analogs due to bioequivalence differences (initial TI dose is about 2 times the RAA dose). 5, 6

Practical Limitations

• The requirement for periodic pulmonary function monitoring creates additional healthcare visits and costs beyond standard diabetes care. 2
• Inhaled insulin is not recommended for treatment of diabetic ketoacidosis. 4, 7
• The medication must be used in combination with long-acting insulin in patients with type 1 diabetes and cannot serve as monotherapy. 4, 7

Clinical Context

While inhaled insulin offers advantages including faster onset of action, lower rates of late postprandial hypoglycemia, and less weight gain compared to injectable rapid-acting insulin analogs 1, 3, the pulmonary safety concerns and contraindications in lung disease make it unsuitable for a significant proportion of patients who might otherwise benefit from these advantages. The American Diabetes Association guidelines clearly state these contraindications apply to all patients with chronic lung disease, making this an absolute rather than relative contraindication. 1, 2