I've never tried a fast before, but I keep hearing that it can help jump-start weight loss. Has anyone tried this? I'm concerned about what it might do to blood sugars.

No, I haven't

What would your fast involve? Would you drink liquids during the day or what?
How long would you have to fast?

If your only drinking liquids and not getting enough carbs you could well have a low blood sugar.

I think the best thing to do is check with your medical professional before attempting a fast.
It's always better to be safe than sorry.

There are a bunch of different types of fasts advertised. Some include drinking fruit juice, so that would give me enough carbohydrate.

Juice will certainly take care of the carbs.
Juice also taste good.

Be careful with the juice.
When I had to give blood for my knee surgery I had some oj or was planning too. My dietician told me to be careful with it because it will shoot your blood sugar up and then drop it.

That's one of the things that concerns me about a juice fast - all that simple carbohydrate. What if I just drink water or tea?

Water and tea are fine to a point.
But you need carb in some form

They say T2s don't go low.
I'm an unusual bird if that's true.
If I don't get enough carbs I go low.
Lows are horrible.

I think if you have lows at least in part depends on the type of medication you take. Even people who don't have diabetes sometimes have low blood sugars, but I believe it's rare.

This whole thing with fasting is too complicated!