Can you over-fast for these blood tests?

Factual Questions
1

It slipped my mind but I have some follow-up blood tests scheduled today. My lab form is specifically dated for today. Since I forgot about it, I didn’t time my fasting right. I think the last time I ate was about 11-12 hours ago, and the lab won’t be open for 3 more hours.

I need a comprehensive metabolic, lipid panel, and glycohemoglobin done. I wasn’t given any instructions in regards to fasting.

Anyway - I can either eat now, and go right before the lab closes, and have been fasting for about 7.5-8 hours, or I can go as soon as they open and have been fasting for 13-15 (can’t remember exactly when I ate). Is one preferably over the other? Will either ruin the results?

2

I have no professional experience, but the nurse who gave me the current lab orders for my A1C and lipids told me to fast for at least 8 hours but not more than 12. I don’t know if that’s just a general guideline or not. Or if it’ll mess up the results if you wait too long, or if they’re just concerned about someone who’s been fasting for more than 12 hours driving to the hospital for the stick.

3

A1c doesn’t require any fasting. Dunno about lipids…

4

triglycerides and fasting glucose levels need to be fasting. I’m okay with fasts ranging from 10 to 15 hours in my patients.