. . . catechins make the difference

Green tea (and its even healthier cousin, white tea) is already known for multiple health benefits, most of them having to do with antioxidant and anti-inflammatory polyphenols called catechins. Numerous studies have shown that green tea is protective against heart disease, cancer, osteoporosis, and a host of other health problems, and that it promotes detoxification and weight loss.

Recently researchers in China reviewed all the randomized controlled trials that have been published to date on green tea/green tea extracts and glucose control and insulin sensitivity in humans. They concluded that green tea significantly reduced fasting glucose in those whose blood sugar was too high; reduced hemoglobin A1c (a long-term measure of blood glucose control), especially in subjects at risk for metabolic syndrome; and lowered fasting insulin concentrations.  The higher the catechin content the better the results were.