A 72-year-old male with type 2 diabetes presents for a refill of his insulin glargine (Lantus) and insulin aspart (Novorapid) pens. He reports that his blood sugars have been consistently high recently despite taking his insulin as prescribed. Upon questioning, he mentions he stores his 'backup' insulin pens in the refrigerator, but leaves the pens he is currently using on his kitchen counter. It is currently summer, and his kitchen can get quite warm. What is the most likely reason for his elevated blood sugars?

Question: A 72-year-old male with type 2 diabetes presents for a refill of his insulin glargine (Lantus) and insulin aspart (Novorapid) pens. He reports that his blood sugars have been consistently high recently despite taking his insulin as prescribed. Upon questioning, he mentions he stores his 'backup' insulin pens in the refrigerator, but leaves the pens he is currently using on his kitchen counter. It is currently summer, and his kitchen can get quite warm. What is the most likely reason for his elevated blood sugars?

Answer options:

• He is likely experiencing an increase in insulin resistance due to age.
• The insulin glargine is interacting with his other medications, reducing its efficacy. ✅ The insulin aspart is losing potency due to improper storage at room temperature.
• The insulin pens are being stored in direct sunlight, causing degradation.

Correct answer: The insulin aspart is losing potency due to improper storage at room temperature.

Explanation: Once opened, insulin pens can be stored at room temperature (below 30°C for most, check product monograph) for a limited duration (typically 28-56 days). However, exposure to high temperatures (like a warm kitchen in summer) can cause insulin to lose potency more rapidly, leading to hyperglycemia. While direct sunlight is harmful, simply being in a warm environment is enough to cause degradation.