Drinking green tea supplements for up to a year can slightly lower your fasting blood sugar by about 1.4 points — and it seems to help your body manage sugar better, not just by coincidence.

Drinking green tea for less than 12 weeks might lower your blood sugar more than drinking it for longer, which suggests the benefit might fade if you keep taking it.

Drinking green tea supplements might lower your blood sugar a bit, but it doesn’t help your body use insulin better in the short term — so your insulin levels stay about the same.

Some people think taking green tea in pill form might lower your blood sugar better than drinking green tea, because the pills give you a stronger, more steady dose of the good stuff—but we’re not totally sure yet because studies don’t all agree.

If you drink less than about three cups of coffee a day, green tea extract might help you burn fat better—but if you’re already a big caffeine drinker, it might not help as much.

Drinking green tea supplements won’t noticeably lower your long-term blood sugar levels, even if you take them for up to a year — so it’s not a reliable way to manage diabetes or blood sugar over time.