Hi
@jingyd36 a veggie/vegan diet isn't any better or worse than a traditional meat and two veg diet, its all about balance, variety and ensuring you get all the nutrients your body needs. e.g. veggie who lives on pizza is just as unhealthy as a meat eater who lives on bacon butties
In my own experience I found my old veggie diet was very very bad for my HbA1c, I ate porridge, lots of fruit and pasta etc. I didn't realise it at the time but even though I didn't eat refined carbs and sugars (everything was wholegrain, high fibre etc and cakes and biscuits were very very occasional treats) my diet was still high carb and had lot of sugar from fruit (average apple has about 4 teaspoons of sugar in it).
I wasn't obese (never have been) but diabetes is in family. After diagnosis I bought a meter and tested my own bodies reaction to foods, I had a shockingly high blood glucose spike after porridge, So I now follow a lower carb with healthy fat veggie diet, I also had carb flu but once I upped my healthy fats (avocado, nuts etc) I felt so much better.
If you are concerned about not becoming diabetic I would suggest lowering (not cutting out) your carb intake, making swaps such as mashed cauliflower instead of/or bulking out mashed potatoes, reducing amount of fruit and increasing low carb vegetables etc. Courgette noodles instead of pasta etc
There is a veggie low carb forum that has recipes on it f you want to have a look for some inspiration.