The polyphenol antioxidants found in tea are thought to help reduce blood sugar and insulin levels. They're also thought to increase insulin sensitivity. Accordingly, several studies report links between regular tea consumption, improved blood sugar control and a lower risk of developing type 2 diabetes. A recent review observed that those drinking 24 oz (720 ml) of oolong tea per day had a 16% lower risk of developing type 2 diabetes. Another study reported that diabetics who consumed 50 oz (1.5 liters) per day had up to 30% lower blood sugar levels at the end of a 30-day study. However, the specific effects of oolong tea are generally not as well researched as those of green or black tea.