2008 Clinical Practice Guidelines - Canadian Diabetes Association

2008 CLINICAL PRACTICE GUIDELINES
S172
Continuing to use the cutoff of 10.3 mmol/L postscreen is
reasonable to presume the presence of GDM. Retrospective
studies published since the 2003 guidelines indicate a threshold
of 11.1 mmol/L would give a false positive rate of 7%
for GDM diagnosis (105) and be 79% predictive of GDM
(106). There were increased cesarean delivery or shoulder
dystocia rates once the screening result was ≥11.1 mmol/L,
even if GDM was not diagnosed (106). A1C testing remains
too insensitive (107), and the GDS is a better screening test
than the FPG test (108). A large retrospective cohort study
confirmed that the 7.8 mmol/L cutoff is valid for white people,
but there are minor racial differences (109). These
guidelines for diagnosing GDM are robust in terms of predicting
macrosomia or the need for cesarian delivery (110).
In the presence of a screening value of 7.8 to 10.2 mmol/L,
a 75-g OGTT is indicated, with samples at 0, 1 and 2 h.
Normal PG levels are fasting plasma glucose (FPG)