Preanalytic Laboratory Standards (Letters to the Editor)

We thank our Canadian colleagues for their interest in our recent article and, in particular, their observations on the need for the 2-h sample with a 75-g OGTT. We note that 25% of their large cohort of 10 773 women had an abnormal 2-h sample using the IADPSG diagnostic criteria and therefore their understandable caution about missing the diagnosis of gestational diabetes mellitus.