Green tea has high anti-oxidating properties and is great for overall health. Substituting green tea with your latte, frappuccinos or milk shakes is a good mean to reduce calories and sugar intake while loading up on polyphenols at the same time. However, contrary to the claims of some studies, Green tea does not have any direct impact on your blood sugar levels. Studies which suggest that green tea helps in insulin sensitivity has yet to provide substantial evidence.
In fact, according to the author of The American Diabetes Association Guide to Herbs and Nutritional Supplements: What You Need to Know from Aloe to Zinc (2009), green tea extracts is linked to liver toxicity. Fortunately, the beverage is not of concern. However, it is recommended that diabetics use green tea extracts with extreme care.