The aim of the present systematic review and meta-analysis was to examine the changes in serum levels of CRP, adiponectin, resistin, IL-6, and TNF-α, along with changes in glucose profile and body composition in adult T2DM patients following resistance exercise training (RET), compared to age- and sex-matched adults with similar characteristics, but not engaged in any form of exercise. This evidence concerns the gene RETN and type 2 diabetes mellitus.