Are Oral Hypoglycemics Enough To Control High Levels Of Sugar?

hi, my father is a 76-year-old male who is a chronic smoker. he was never diagnosed with diabetes mellitus till now. for the past 3-4 months, he started losing weight and started to get up 4-5 times at night to urinate. He finally went and saw a general practitioner 3 days ago, and he suggested to do a fasting as well as PP blood sugar check. his fasting returned as 328 and his PP returned as 628. The doctor put him on oral hypoglycemics for 10 days and advised him to recheck the FBS and PP after 10 days. He has been on the medicine for 2 days, and he is still getting up 4-5 times at night to urinate. he does not have excessive thirst, fatigue, fever, nausea or vomiting tendencies. He did have a dry mouth before starting on the medicines, but he now states that feeling is gone. My question is whether oral hypoglycemics are enough to control such a high level of sugar. The physician also asked him to drink a lot of fluid.