i understand your concern
in morning and few other times.
few tests need to be done- BP of the child, vision testing, fundus examination, hemogram, these are few baseline tests . possible causes- anaemia
, poor vision, hypertension
these need to be ruled out.
DM presenting like this is unlikely. frequent urination
check how thirsty he is ? how much water he drinks? if he is dehydrated? this could lead to dizziness
get all these tests done let me know the results