GhOsTID said "If you already have diabetes/prediabetes there's no evidence to show green tea has any benefit just as an FYI. If you like unsweetened green tea and it will help you replace a sugary alternative then it could have some effect but that's just as a lifestyle change.
Consult a doctor or at the very least get a referral(might not be needed but may as well) to Public Health to see a dietitian and I can't remember the name of the Chronic Disease Prevention(I can't remember their title right now sorry) person and you can ask t hem. They are great at what they do and most importantly they can equip you with the knowledge to make informed decisions regarding your health because for instance wanting to drink green tea might not be harmful on it's on but if you're trying to save money it may end up purely being an increased cost or even worse if you're expecting it to improve your health so you can avoid doing something that actually would have a positive effect and it doesn't can leave you where you no longer have that initial option available and in a worse situation overall.
Take care, I hope you have good results. "
Chronic Disease Education Program
1 204 509 7852