Gestational diabetes mellitus (GDM) is one of the most prevalent pregnancy complications that is characterized as abnormal glucose metabolism newly manifested during pregnancy (۱). Studies have shown that women with GDM are at a higher risk of developing cardiovascular disorders later in life (۲). Several studies have suggested a possible link between endothelial dysfunction and insulin resistance and hyperglycemia (۳). Nitric oxide is a vasoactive mediator produced from L-arginine in endothelium that plays a key part in regulating endothelial functions. Asymmetric dimethylarginine (ADMA), a L-arginine analog, is an endogenous inhibitor of Nitric oxide synthase and it can decrease nitric oxide production (۴). There is emerging data suggesting that elevated ADMA levels in circulation can promote endothelial dysfunction and interfere with vasodilatation (۳). Furthermore, previous studies have also reported higher ADMA levels after delivery in women with previous GDM. This suggests elevated ADMA levels may play a role in pathogenesis of insulin resistance and hyperglycemia during pregnancy (۱). In this systematic review and meta-analysis, we aim to summarize the available evidence concerning the association of ADMA concentrations in maternal serum and GDM during pregnancy.