The use of assays of glycated serum proteins (glycohemoglobin and fructosamine) as markers of glucose homeostasis is becoming a common modality in the evaluation of the pregnant diabetic patient. The purpose of this review is to provide basic information on the interactions between glucose and the protein molecules that lead to the formations of this complex, and to evaluate these tests for their efficacy in the screening and diagnosis of gestational diabetes mellitus, the identification of fetal congenital anomalies and in their relation to early fetal wastage, fetal macrosomia and neonatal complications.