Drinking green tea has been described as being beneficial for reducing the risk of diabetes type 2.
A retrospective cohort study performed in Japan, found a 33% risk reduction of developing type 2 diabetes was found in subjects consuming six or more cups of green tea daily compared to those consuming less than 1 cup per week https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3689013/
However, green tea supplementation does not seem to be efficacious in the treatment of diabetes. The results of a systematic review and meta-analysis suggest that the supplementary intake of green tea had no significant effect on FPG, fasting insulin, HbA1c and HOMA-IR in patients with T2DM. https://pubmed.ncbi.nlm.nih.gov/33285391/
Akdogan, M., M. N. Tamer, E. Cure, M. C. Cure, B. K. Koroglu, and N. Delibas. 2007. 'Effect of spearmint (Mentha spicata Labiatae) teas on androgen levels in women with hirsutism', Phytother Res, 21: 444-7.