The first thing to do is do NOT panic. I am one of the many thousands who have changed my routines and gone from really bad to normal.
Change of diet and exercise are key. Just make the right food choices and make substitutes where possible.
Myself I cut out:
Potatoes, cakes, fancies, bananas, high wheat products, rice, paste and fish and chips.
In came:
Rye, Raspberries, Strawberries, very dark (90%) chocolate, vegetables, tomatoes, bacon, sausages, eggs, cheese and low carb bread. I avoid all carbs after 6pm.
I also take exercise after every meal (only 10 mins) to get rid of any quick acting glucose.
I was on high power drugs (glycho something or other) with a HBAIC reading of 124 and now off drugs for 3 years and a reading of 44.
You will find thousands of people on here to advise so you are not alone.
Oh - and treats are OK from time to time.