One could expect some of the beneficial effects of coffee to be similar for tea, since some of the compounds are similar. A study in China has found that drinking large quantities of Oolongtea—a liter a day—is beneficial for glycemic control in people with diabetes. But research on tea in the U.S. has not shown the type of beneficial effect we see for coffee, probably because people in the U.S.tend to drink tea that is weaker in strength and tend to drink less of it.