what does it feel like to have low blood sugar?

Hello, I've a cat that has diabetes so I can't really ask him. However before meals he gets very nervous and irritable. He didn't used to be that way. He was much more relaxed around feeding time before he had diabetes. I make sure his blood sugar is between 100-300 as per my doctor. I figure maybe if I understand his feelings then I can make better choices about how to handle him.