Gestational diabetes mellitus (GDM) is an asymptomatic disease. Diagnosis is based on a oral glucose tolerance test (OGTT) requiring pregnant women to absorb 75g of glucose while fasting since midnight and to stay sober for another two hours. These OGTTs are poorly tolerated by pregnant women. As many OGTT are false positive according to self-monitoring blood glucose (SMBG), the investigators need now to determine the percentage of OGTT results that are false negative.

The comparison of the two tests (OGTT and SMBG) in the same patient with normal results of OGTT will determine the exact percentage of false negative OGTT results.

The opinion of women will also be taken into account. In the everyday clinic, many report that they prefer SMBG to OGTT because they do not have to be fasting, to drink non palatable drink and to attend a 2-hour visit in their schedule. However, no opinion study has yet been performed, the investigators will investigate formally what women think using a questionnaire.

Inclusion Criteria:

• positive GDM screening test (glycemia post-50g of glucose ≥ 7.2 mmol/L),
• between 24 and 28 weeks of gestation from the last menstruation,
• single pregnancy,
• able to read and understand French.

Exclusion Criteria:

• known type 1 or type 2 diabetes,
• disease or treatment interfering with the metabolism of glucose,
• deficiency may hinder the understanding of the study.

Women with abnormal GDM screening test.