Insulin Get In Action Delay

A whole variety of things can effect how quickly or slowly your insulin appears to act. Heat, exercise, injection site, other medications, alcohol, hormones (bloody hormone - hate them), time of day etc. I personally find a great deal of variability in how quickly my insulin acts. Although my morning that my insulin action is constistently very delayed and still is acting and dropping my BG 5 hours after. So I tend to take my morning bolus insulin about 35 mins before breakfast to try and give it a head start and avoid spikes.

Morning,

The Libre does have a delay behind true BG levels due to the way it works. It doesn't measure your actual BG and as such can be between 10 to 20 minutes behind what a finger prick test will show.

As @Flakey Bake has explained, there are many factors that can affect insulin's peak action and effectiveness.

Are you noticing a delay in BG dropping with every meal? It's possible that you see a delay with high GI meals which is normal. The usual profile for these meals is a large spike followed by a sharp drop.

Another possibility is that your in use bolus insulin is losing potency. There are a few reasons for this including age and exposure to heat or cold. However, if you're dropping low post meal within the typical 5 hour action time then this would suggest that your insulin is working fine - and you've taken too much.

All that said, it may also be worth your while checking your basal dose is correct.

Good luck
Grant