Diet can manage this, but it takes alot of effort. What kind of cereal did you have? What is the gylcemic load of the carbs? You know you can't just watch sugar content as in "sugar" wording but all sorts of things that create the same reaction in the body.

I can't eat carrots or bananas because the "sugar" goes straight into the bloodstream and affects the insulin levels. I'm not diabetic, I'm functionally hypoglycemic and trying to keep from becoming diabetic.

Losing weight is the overall best thing to do to manage or eliminate this problem.

I'm sorry you're having to treat for this. Not only is it expensive, but it's a real hassle not to mention the highs and lows you'll get if your body doesn't respond the way you expect.