Daily green tea consumption, particularly in seasonal variations, plays a pivotal role in maintaining fasting blood glucose and insulin levels, with P. vulgatus identified as a potential mediator in the negative association between green tea intake and fasting blood glucose levels. Green tea may improve glucose metabolism by suppressing the abundance of P. vulgatus, which is linked to elevated blood glucose levels in individuals without T2DM. The gene discussed is INS; the disease is type 2 diabetes mellitus.