One-step strategy:

Perform a 75-g OGTT, with plasma glucose measurement when patient is fasting and at 1 and 2 h, at 24 - 28 weeks gestation in women not previously diagnosed with diabetes.

The OGTT should be performed in the morning after an overnight fast of at least 8 h. The diagnosis of GDM is made when any of the following plasma glucose values are met or exceeded:

· Fasting: 92 mg/dl (5.1 mmol/L)

· 1 h: 180 mg/dl (10.0 mmol/L)

· 2 h: 153 mg/dl (8.5 mmol/L)

Two-step strategy:

Step 1: Perform a 50-g GLT (nonfasting), with plasma glucose measurement at 1 h, at 24 - 28 weeks of gestation in women not previously diagnosed with diabetes.

If the plasma glucose level measured 1 h after the load is ≥130, 135, or 140 mg/dl (7.2, 7.5, or 7.8 mmol/L, respectively), proceed to 100-g OGTT.

Step 2: The 100-g OGTT should be performed when the patient is fasting.

The diagnosis of GDM is made when at least two* of the following four plasma glucose levels (measured fasting and at 1, 2, and 3 h during OGTT) are met or exceeded (Carpenter-Coustan criteria [193]):

· Fasting: 95 mg/dl (5.3 mmol/L)

· 1 h: 180 mg/dl (10.0 mmol/L)

· 2 h: 155 mg/dl (8.6 mmol/L)

· 3 h: 140 mg/dl (7.8 mmol/L)