The most common form of hypoglycemia in people who are not on medications causing hypoglycemia is reactive hypoglycemia.
In the average person's postprandial blood sugar curve, the blood sugar rises during and after the meal, then falls to slightly below the starting blood sugar, and then rises back to the starting blood sugar.
In many people whose pancreata are struggling to make enough insulin, or whose initial insulin response to meals is blunted (ie not making enough incretins or not responding to incretins), after the initial blood sugar rise, there is a drop in blood sugar that is much more dramatic than the normal drop that results in hypoglycemia. It is called reactive hypoglycemia because the hypoglycemia is caused by an over reaction to food.
It should be treated by a diet with no big meals, and snacks through the day. An extreme low carbohydrate diet is usually fairly good at preventing lows, but it isn't necessary; a diet in which a person eats a roughly consistent number of carbs every couple of hours during the day works as well (meals should get smaller in the evening). For milder cases, simply avoiding big meals- and especially avoiding big meals that are followed by exercise (a classical bad move would be a wedding banquet followed by energetic dancing)- is sufficient.