Hi
@chrissyrobbo, do you inject your insulin or do you use a pump?
If you inject I think it might depend on your basal insulin, I can't pretend I know much about it, but I believe different ones take different amounts of time for changes to take affect, so it would also depend on how long you are ill for, whether the changes to your dose would make any difference whilst you are still ill. I must admit I was never told to increase my basal whilst ill when I still used to inject, corrections were made with boluses.
My pump has a pre-set temporary basal for illness and that's 120% of my usual basal.