The pooled standard mean difference of FSH was −0,237 (CI95%:–0,582 to 0,108; P = 0.17; I2: 95,83%; Ndiabetic = 2167, Ncontrol = 2041; Egger's test: 0.06; Begg's test: 0.15), with diabetic men having lower levels of FSH than those without diabetes (Fig. 2). This evidence concerns the gene BRD2 and diabetes mellitus.