To the Editor: McIntyre and Oats1 suggest that Australian medical practitioners should adopt the new International Association of the Diabetes and Pregnancy Study Groups (IADPSG) diagnostic criteria for the management of gestational diabetes mellitus (GDM),2 mainly because of the findings of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study.3 If adopted, a significant number of women will be diagnosed with GDM if their only blood glucose level (BGL) abnormality is a fasting BGL of 5.1–5.4 mmol/L. The quoted studies do not provide outcome data to confirm benefit at these levels.4,5 In addition, women currently diagnosed with GDM on the basis of a 2-hour BGL of more than 8.0 mmol/L but below the new IADPSG level of 8.5 mmol/L2 will no longer meet the criteria. But outcome data show a benefit of management at these levels.4 Also, the US study on treatment for mild GDM used a 100 g oral glucose tolerance test (OGTT)5 with a 2-hour BGL cut-off that approximates 8.0 mmol/L on a 75 g OGTT.6 Thus the two quoted outcome studies demonstrate benefit of treatment at BGLs that will no longer be accepted for the diagnosis of GDM.
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