The number of pregnant women affected by gestational diabetes mellitus (GDM) is increasing among Caucasians, and East Asians. GDM also increases the risk for later advent of type 2 diabetes mellitus (T2DM), obesity, and cardiovascular disease in both women and their offspring. The underlying mechanism of GDM is not fully elucidated. Incretins such as glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), have been suggested to have a role in maternal metabolism and weight as well as fetal growth. These hormones might be implicated in mechanisms that compensate for the increment in glycemia and insulin resistance seen during pregnancy, while other factors, such as heredity, environment and lifestyle, but also different race/ethnic background might also lead to the comorbid health problems. Some studies indicate that pregnancy is associated with a diminished GLP-1 response which is more prominently evident in women with GDM and normalizes after delivery. Postprandial GIP level seems to be unaffected by pregnancy, despite its increased level in GDM. On the other hand, the reduced incretin effect observed in GDM may represent a risk factor for obesity, T2DM and metabolic disorders even in the offspring of these women. Further investigations are needed to establish the exact role of incretins in pregnancy and gestational glucose intolerance.