ADIPOQ and type 2 diabetes mellitus: The reasons for excluding the remaining 360 articles were: articles that were reviews, editorial, conference abstract and brief report (n = 80), articles that were performed in animal and in vitro models (n = 50), articles evaluating adiponectin gene polymorphisms in patients without T2D (n = 90), articles didn’t assess SNPs of − 11377 and + 276 in T2D patients (n = 80), articles didn’t provide sufficient information on the numbers of genotypes (n = 60).