Forgot to mark med on diabetic chart- thoughts?

Hi everyone,

I am a new student nurse in my first term. I recently gave a pt with diabetes an oral hypoglycaemic and while I marked it on his MAR as completed I didn't mark it on his diabetes flow chart as stated on the MAR. I completely forgot and didn't realize it until much later. We are not allowed to be on the floor without our instructor so I couldn't go back and late entry it and won't be back for another week. How serious is this? Should I be calling my clinical instructor? Thanks for your thoughts.
When in doubt, call your instructor.