Abstract                The condition known as gestational diabetes mellitus (GDM) describes as an intolerance to glucoseThat first occur or progresses during pregnancy is the most common metabolic illness, and impacts up to25% of pregnant women.  It has been demonstrated that omentin-1, which originates from both human placental and adipose tissue can serve as an insulin resistance mediator. It was initially identified as a secretory factor specific to visceral fat and showed that recombinant omentin-1 administration increased insulin-stimulated glucose transport in vitro which may increase insulin sensitivity, both glucose and insulin can down regulate omentin-1 which reduces levels in overweight women with polycystic ovarian syndrome. Moreover, those with diabetes and obesity had lower omentin-1 levels. Adipokines influence a variety of metabolic processes, including insulin sensitivity and secretion, inflammation, appetite control and adipogenesis regulation. This study was carried out with the aim of determining the serum omentin-1 level in pregnant women with and without gestational diabetes and determining any potential correlation between the adipokine omentin-1 and gestational diabetes. Multicenter case – control study, the cases collecting (pregnant women in the third trimester of pregnancy) will be divided into: Group A: 45 apparent healthy pregnant women without GDM as control. Group B: 45 pregnant women with GDM (patient). venous blood sample (5ml) in gel tube, of all subjects were drown after an overnight fast, and serum samples were stored at -20C° until omentin-1 assay by enzyme linked immune sorbent assay ELISA. Forty-five patients with gestational diabetes and 45 without were studied. Serum levels of omentin-1 were significantly lower in patients with gestational diabetes mellitus compared with those of the control group, p = 0.0001, hence this biomarker can serve as prognostic indicator for gestational diabetes.