I was diagnosed with an HbA1c of 50. As others have said, many people are diagnosed with much higher levels so I don't think the word "severely" is justified. Diabteic, yes, severely, perhaps not.
I was back in normal range in four months, with no medication but by using a low-carb "keto" approach - around 20g carbs/day. I was "offered" medication at diagnosis, but chose not to take it and am glad I didn't.
That approach worked for me - I find it easier to cut all carby food rather than try to count and monitor a higher intake. Other people have got to the same result using different techniques, and you have to find what works for you.
One thing I would suggest is getting hold of a blood glucose monitor and using it to test the effect that various foods have on the glucose in your system. Whatever you do, getting the feedback from the testing is really a key piece of information about how you are managing things day to day.
Best of luck!