I dont think you have pre-diabetes type-2, first regarding your age but also that you are quite fit. Eating somewhat fastfood and choclate will not affect that. Usually you get DMT2 either due to obesity or aging and since you are none of the above I wouldnt worry about it.
And I diabetes type-2 is not really known to be inherited in any matter. Ok there are some genetic factors but not as prenounced ones as in diabetes type-1.
On the other hand i dont know why you have this symptom. Go and get it checked if you're worried.
My grand ma had diabetes.
My parents dont . Neither do my brothers/ sisters.