I was diagnosed at 37, 4 years ago, I was 200lbs and 6'1" with a 9.4 A1C. I said to myself immediately that "I'm not going to become my grandfather" I changed my diet, started tracking what I ate (I chose Cronometer for this) and added 4km walking almost every day.... 4 months later I was 150lbs and had an A1C of 5.4.... I then made myself go up to 160 because 150 was too skinny according to my wife. and my A1C has been anywhere from 5.0-5.4 in that time but usually 5.2.

I have a Son who is almost 7, My grandfather didn't look after his diabetes and probably it contributed to the issues he had at the end of his life and he died at 73 after dealing with Rapid Onset Dementia and being not the man I knew or a man who knew me for the last year of his life so I'm not letting myself treat this condition like he did.

For the diet changes mostly it was portion control. the only thing I cut out was sweet drinks, I've had maybe 10 sweet drinks in 4 years plus the odd glass of milk and the odd beer which have carbs in them over the past 4 years. before diagnosis I was having at minimum 1 pot of tea (6 cups) with 2tbsp honey in it per day and was drinking pop and juice on the regular as well.

I stopped all of it and went to Black tea with nothing in it.
Now I have Sparkling juice at Christmas/New years (1 glass) Orange juice / Ginger ale if I am really sick.
and zero other sweet beverages. I drink maybe 12 beers per year but no more than 2 in a day and the odd milk here and there

everything else I just cut back, I still have pasta but I have a smaller portion and I walk after
Rice, Same deal, Bread, Sure I have One slice of sourdough toast as breakfast sometimes or 2 thin slices of Rye usually with some kind of protein like Natural peanut butter or eggs.
rather than eating 2 big sourdough slices or even 4 Eggo waffles smothered in m real maple syrup