How do people treat low blood sugar?

Depends on cause: The body naturally adjusts the blood levels of sugar, mainly glucose. If you have low blood glucose, you should be investigated to determine the cause and treat the cause. Otherwise, in a healthy person, usual balanced diet is sufficient to maintain normal blood sugar levels.

Diet: Of course, much depends on the underlying cause, but in general, avoiding simple carbohydrate (sugars) and replacing them with complex (think fiber, whole grains), and protein ;and considering more frequent, smaller meals.