Maybe HE is only interested in the fasting numbers, but you should be concerned with a lot of testing. It's the only way you know the effects of food,medication and exercise.
"...WHY IS MY DOCTOR ONLY CONCERNED WITH MY FASTING SUGAR LEVELS?"
Dunno, we can't read his/her mind. Why don't you ask the doctor? You should ask for an A1c test. An A1c is used to verify diabetes, prediabetes, or normal. BTW, what is your fasting level?