Photon
Member
I’ve never had any issues with the insulin ,I’ve gotten multiple humalog pens and they all functioned how they should have and this was during the summer months.
I think the storage constraints for temperature is more critical once the medication has been opened and you start using it.
I also have a few diabetic friends who leave their pens out in ambient room temperature without issue even after they start using the medication.
i use 10ml vials and def can't finish those in a month, this is a random study i found via google where they tried simulating insulin use in kenya, (hot temp, inability to keep it cool etc)
it does degrade under high heat and it's usually visible

Stable even at 3m without refrigerating..

tldr, good at room temp, don't leave in your car or direct heat?
Heat-stability study of various insulin types in tropical temperature conditions: New insights towards improving diabetes care
Strict storage recommendations for insulin are difficult to follow in hot tropical regions and even more challenging in conflict and humanitarian emergency settings, adding an extra burden to the management of people with diabetes. According to pharmacopeia unopened insulin vials must be stored...
