A recently reported systematic review and meta-analysis of the randomized controlled trials on the effect of the supplementary intake of green tea on fasting plasma glucose, fasting insulin, hemoglobin A1c, and the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) in patients with T2DM selected only 14 articles out of 780, after excluding animal studies, unrelated studies, or those with insufficient data. This evidence concerns the gene INS and type 2 diabetes mellitus.