From my own battle with T2 diabetes and now heart disease / aneurysm I’m on a keto type diet since I was 62. Key thing is to focus on eating “real food” - eating meats and vegies and avoiding processed foods (usually heavy in sugary carbohydrates and comes in a box, packet or bag) and sugar in all its forms and severely cut down booze and don’t smoke.. also re fruit try and eat them whole, rather than being juiced; otherwise too sugary. My weight shot down from 240lbs to 200lbs in 6 months some 3 years ago and have since kept it off. In this area best to educate yourself and do your own research via books or over the internet. Anywhere along the spectrum of vegan to carnivore is likely ok provided you eat no junk or sugar and if you are vegetarian or vegan that you properly supplement with iron, B12, zinc etc etc. Proper nutrition is very important and if struggling see a specialist.
Note I’m not a doctor nor a health provider whatsoever- nonetheless best of luck to you.