Intranasal insulin therapy: the clinical realities

Area of Science:

• Endocrinology
• Metabolic Disorders
• Drug Delivery Systems

Background:

• Diabetes mellitus management relies on effective insulin delivery.
• Subcutaneous insulin injections are the current standard of care.
• Exploring alternative insulin delivery methods is crucial for patient convenience and adherence.

Purpose of the Study:

• To compare the efficacy and safety of intranasal insulin versus subcutaneous insulin in patients with type 1 diabetes.
• To evaluate metabolic control, including haemoglobin A1c levels.
• To assess safety parameters such as hypoglycaemia frequency and nasal mucosa physiology.

Main Methods:

• An open, crossover randomized trial involving 31 insulin-dependent diabetic patients.
• Patients received intranasal insulin at mealtimes for 1 month.
• Patients then received subcutaneous fast-acting insulin at meals for 1 month, with both groups using intermediate-acting insulin at bedtime.

Main Results:

• Intranasal insulin exhibited low bioavailability, requiring doses approximately 20 times higher than subcutaneous insulin.
• Metabolic control, measured by haemoglobin A1c, slightly but significantly worsened with intranasal insulin.
• Six patients were withdrawn due to metabolic dysregulation during intranasal insulin therapy; hypoglycaemia frequency was similar between groups.

Conclusions:

• Intranasal insulin demonstrated significantly lower bioavailability and therapeutic efficacy compared to subcutaneous administration.
• The observed metabolic deterioration and high failure rate render intranasal insulin an unrealistic alternative to current injection methods.
• Nasal mucosa physiology remained unaffected, but safety and efficacy concerns limit its clinical application.