The diagnosis of gestational diabetes mellitus (GDM) using a 75 g oral glucose tolerance test: A prospective...

Screening for Gestational Diabetes Mellitus (GDM) is controversial. This prospectivestudy compared different sets of diagnostic cut-off points for plasma glucose measurements following a 75 g Oral Glucose Tolerance Test (OGTT).

Women who had maternal risk factors for GDM were recruited at their convenience attheir first prenatal visit and consented to a one-step OGTT at 26-28 weeks gestation.All women fulfilling the World Health Organization (WHO) 2013 diagnostic criteriareceived standard care for GDM.

Of the 202 women, 139 (69%) had one risk factor for GDM and 63 (31%) had > 1.Using the WHO criteria, 53% (n = 108) had GDM compared with 35% (n = 71) usingCanadian criteria and 18% (n=36) using National Institute for Health Care Excellencecriteria (NICE) criteria (both p<0.001). Of the 108 women, 50% (n = 54) requiredpharmacological treatment to control hyperglycaemia. If the Canadian criteria wereapplied, 11/54 (20.4%) women would not have received hypoglycaemics. If the NICEcriteria were applied, 36/54 (66.7%) women would not have received hypoglycaemics.Maternal insulin, HOMA-IR and C-peptide measured at the time of the OGTT showed evidence of increased insulin resistance in women who had GDM based on the WHOcriteria but who had a normal OGTT based on the Canadian or NICE criteria.

Under stringent research conditions, our study suggeststhat the Canadian and, in particular, the NICE criteria are not identifying women who may benefit fromimproved glycaemic control. These findings support the need for the planned review of the NICE guidelines on GDM in 2020.