Figure 1.

Fasting plasma glucose levels in normal pregnancy and GDM. In preconception, women who later go on to have normal pregnancies exhibit a mean FPG of 81 mg/dL (12). Mean FPG levels for women with normal pregnancies slightly decrease to 80 mg/dL, 77 mg/dL, and 76 mg/dL in the first, second, and third trimesters, respectively (12). A study by Sesmilo et al showed that first trimester FPG may vary, as their cohort of 6845 women had a mean FPG of 83 with a standard deviation of ± 7.3 mg/dL (132). Of these women, 10.2% developed GDM, which showed that women with a FPG ≥ 88 mg/dL in the first trimester were 1.82 times more likely to be diagnosed with GDM in the second trimester (132). Gestational diabetes mellitus is diagnosed in the first or second trimester if the patient measures a FPG ≥ 92 mg/dL by the 1-step OGTT (99). In a study by Seabra et al, they showed that GDM patients had a significantly higher FPG (90 mg/dL) compared to women without pregnancy complications (FPG 77.8 mg/dL, P = 0.016) in the third trimester (133).