For blood glucose control, you may also want to explore raw puer tea, tartary buckwheat tea, mulberry leaves tea and bitter melon tea.
Tartary buckwheat tea contains rutin which some research suggest it may be helpful. I prefer to have this in the evening over other tea because it does not contain caffeine. But the glucose lowering effect is not as significant as puer tea.
Came across a number of raw puer tea that works very well for me...over a 5 mmol drop within 2 hrs...dangerous or remarkable. Depends on your perspective. @ <$2/100g I find it to be a cost effective option. Would be good if there were more clinical research into this to understand the mechanism behind it. Unfortunately few researchers seems interested.