When Adele did the video for her hit song "Hello," she riled up the Internet by pouring hot water into a teacup and then (outrage) adding the tea bag. The hashtag #boycottAdele spread around the globe.

But that's not why she's given up her 10-cup-a-day habit. She realized that all the sugar she put in each cup was fueling problems with her weight.

It’s too bad she couldn't adjust to drinking it unsweetened. Studies show that green tea can help lower blood pressure, total and LDL cholesterol levels, and triglyceride levels, and is known to help battle cancer. Oolong lowers inflammation and is a brain booster. Black tea fights inflammation and supports your immune system.

And now it turns out that drinking at least four cups a day of black, green, or oolong (no sugar) is associated with a 17% lower risk of developing Type 2 diabetes over about 10 years. One to three cups cut the risk by 4%.

The findings, presented at the European Association for the Study of Diabetes annual meeting, came from evaluating data on 1 million adults from eight countries.

For all the people in the U.S. who have prediabetes and other risk factors for Type 2 diabetes, this is great news.

But iced tea (almost always sweetened) accounts for 75% to 80% of the tea that Americans consume. It's time to trade that in for a nice cuppa unsweetened hot tea.

Just remember: tea first, then boiling water.

And black coffee is even more effective at decreasing diabetes risk.