Is he a known case of
diabetes? if so, since how long?
320 is pretty high, he needs to go on medications. however, he would require additional investigations to decide what treatment is appropriate for him.
Duration of treatment is variable. Unlike antibiotics course, duration for usage of anti-diabetic medications can not be decided before hand. it depends on how patients respond and how they maintain their diet/exercise
Next Steps
Blood workup and followup consultation