(1) This study may be the first study to evaluate the effects of oolong tea with different storage time in db/db T2DM mice.(2) All three aged oolong tea extracts (2001, 2011, 2020) can effectively alleviate type 2 diabetes mellitus (T2DM), and 2011 aged oolong tea extract exhibited relatively optimal ability to alleviate T2DM.(3) With storage time of oolong tea increasing, oolong tea’s ability to inhibit fat ectopic deposition in liver increases and the ability to activate INSR/IRS/PI3K/AKT/GSK‐3β/GYS‐mediated hepatic glycogen synthesis sig...