I was diagnosed ten years ago. I was morbidly obese.
I wasn't that active then, I used to be, but with work and home life I slipped into the comfortable zone, overeating and under exercising.
I initially looked at all the available information on diets, low carb, high fat, high protein, low GI, vegetable, and pinched bits from all of them. I tried a few while I researched.
I found a lot of "information" on some of the diets wasn't backed by any real facts, or any real studies, and indeed went in the opposite direction to established studies. Some didn't actually achieve the claimed results for me, so eventually I went down a more classical low GI, low fat, low calorie diet initially, working with the NHS who provided me with a dietician, a physio, and a meter.
I got my BG under control, and lost a very substantial number of stones.
Sometime around then the Newcastle diet was just in the news after it's first success on a handful of people.
I decided I still wasn't "reversed" so figured eight weeks of very low calorie diet couldn't hurt.
It seems to be a possible route back to a "normal" diet, as I still wanted to eat out, and quite often needed to grab food when and where I could, so I didn't want the hassle of committing to a limiting diet for life.
My doctor hadn't heard of it, but thought it was my choice, so supported me.
I did the Newcastle diet with Tesco shakes.
At the end, my BG was back to normal, and I was getting a good insulin response.
For me, it was ideal as it completely reset my eating habit as well.
I was conscious that eating had made me diabetic, no one to blame but me for what I ate and my weight.
So after the Newcastle diet, and my previous trawl of what made a healthy diet, it was fairly easy to transit over to a healthy Mediterranean diet. Probably more towards the low GI, low fat end, as it's a healthier option for me,
The other benefit is if I do put on a few pounds, and I have with lockdown, it's easy to simply eat less for a few weeks again,
It's been ten years since diagnosis, seven diabetes free, on a normal diet, with no diabetic complications.
I still think "calories" when I look at food, and can work it out in my head, which is a good thing to me.
I was morbidly obese when I was diagnosed, I had lost a lot of weight when I started the Newcastle diet.
I was working on BMI, so I was still overweight, but I certainly lost more on the diet, down to the point of looking ill.
Whether it was the final push that cleared internal fat, or the speed of loss I don't know, but as you said you were slim, it's a consideration, as your personal circumstances will obviously determine your actions and the outcome.
Have a look at the links below
The very low calorie diet was approved by the NHS as a recognised treatment, but it's not rolled out everywhere.
Health and high quality care for all, now and for future generations
www.england.nhs.uk
The information on the diet is online, the basic plan is
https://www.ncl.ac.uk/media/wwwnclacuk/newcastlemagneticresonancecentre/files/201809 Sample Recipes & meal plans.pdf