Hi
in the day yr correction factor or isf is 1u will lower yr bg level by 4.5mmol which means that less insulin is used to correct you to yr bg target. During the night yr factor is 1u lowers by 2.5mmol so more insulin is used to correct bg, so the higher the mmol is, the less insulin is needed.
Confooosing isn't it?.... but you will get the hang of itb