I don't think you messed your system up because I feel our bodies are built to be stronger than that. Here is something from the Mayo Clinic's website:
http://www.mayoclinic.com/health/reactive-hypoglycemia/AN00934Before my doctor caught my elevating blood sugar, I used to love eating oatmeal with maple syrup in the winter for lunch and an hour or so later, I had to lie down and take a nap. Now I realize that my blood sugar took a dive but since this was before I had a meter or even suspected I was on the verge of diabetes, it was really confusing to me.
I don't know why your blood sugar seems to have dipped like that - I'm presuming it's the blood sugar but if you didn't test, it's hard to know. Although oatmeal has a lot of fiber, it also is full of carbs and if it was sweetened, it may have indeed caused you to have a blood sugar crash. This can happen to non-diabetics also.
I would mention it to your doctor. And I guess I would suggest next time eating a smaller bowl of oatmeal with some protein for breakfast, eggs maybe. That might stop a big blood sugar drop.
That's only my guess. Maybe someone else knows more about this than me.