Fasting shouldn't be bad for people suffering with hypoglycemia.
Why? Because our body is perfectly able to maintain balanced blood sugar while we're not eating food. It's when we eat something that we mess everything up.
Of course your body can maintain balanced blood sugar until there's glucose in the blood and glycogen in the body. Eventually it will start converting body proteins (like muscles) to glucose. So long fasts are not a good idea.
I suggest you to read a book called "Eat stop Eat"
It explains how to fast by not eating for 24 hours twice a week.
It works like that: you eat your dinner on monday at 7 pm and don't eating anything (but drink a lot of water) until 7 pm of thursday. The you keep eating your normal diet for a couple of day and on friday (for example) you have your dinner and don't eat anything until 7 pm of saturday.
As you can see you're indeed fasting for 24 hours but you're never going a single day without food. 24 hours is long enough to provide the benefits of fasting (which include improved glucose tolerance, so it's a good thing for someone with hypolycemia)
People with reactive hypoglycemia have commented they felt good on the protocol.
It's very important to drink much water during the non eating hours. Sometimes brain fog can be reversed with water alone and people with RH tend to be dehydrated.
Buy the book as it's a very easy fast reading.