I haven't heard the dehydration theory but it is interesting. During my last lab work I told the tech that I'd been drinking water all morning and she said water would have no impact on the reading.

I agree. I don't think it has any bearing. If you feel comfortable do your poke as soon as you get up, as long as you do it before you eat anything or drink juce, milk, etc.

I can't stand the thought of jabbing myself upon getting outta bed in the morning. I usually wait 10 minutes, but have waiting as long as an hour before testing. However, I test before I drink coffee becuz I add a little cream and sugar (I confess....I use the real thing and not the fake stuff).
I would think wouldn't change anything as it has no carbs....no calories....nothing...nada in it :)

If you are having an A1C taken drinking water before having your blood taken can increase the volume in your veins and make it easier for the tech to get blood. The A1C measures the sugar remains on your Hemoglobin. Extra water would not effect that.

But for a sugar stick it would not make that much difference. If you are having trouble getting blood...

Adjust the depth of your lancet,
Rub your finger first,
Run warm water over your fingers.

I get up at 6am have coffee, take my other Meds and I always have breakfast at 8am that is when I test.

I Drink water with my Meds and my readings are always the same 98-110. The important thing is to test at the same time. That of course is my opinion and what my Doc suggests.

I'm up at 5:30am, let out the dogs, test my bg, let the doggies back in, feed them and the cat, do exercises and then get ready for work, then eat breakfast and water is good for you, helps to flush out the kidneys etc