metformin dosage

my son is 19, he was put on metformin 1000mg twice a day when he was 15 as he was overweight and had significant insulin resistance after a glucose tolerance test, pre diabetes i think they said, he has recently gained a lot of weight without his lifestyle changing, doctor says eat healthy diet and take more exercise, ruled out checking blood sugar levels, repeating glucose tolerance test or revisiting endriconlogy clinic he used to attend until 16 yrs old
does anyone know how often he should be tested, should his dosage be monitored, how long will he need to take metformin
my son has  autistic spectrum disorder and finds it difficult to visit doctors or deal with this and i am treated like a fussy mother

[WaveRider]

Your son is at max daily dose for Metformin. Considering that doctor's suggestion and common sense for the a past 3 years have been ignored, I shudder to think what his blood sugar levels are. Continuing on this path will only make the diabetes side effects happen sooner. Not a good thing to look forward too.

"should his dosage be monitored"
He needs another oral med and/or injectable insulin but in order to get either one he must see a doctor.

"how often he should be tested"
You can do that with a home test meter found at your local drug stores.