If I go too long without eating I get grouchy, nauseous, shakey.

If I eat too much sugar (not a lot for SAD) but a lot for ME! (One small tub of haagen daaz for example) I become immidiately tired. (So tired I could sleep.) It passes fairly quickly.

I don't eat a lot, but I've noticed this reaction recently.

I've been low sugar / grain / 'carb' for a year, and otherwise feeling great, with plenty of energy. I used to be able to go all day without eating when I was younger, not so anymore! Are these signs of pre diabetes?