Experts still divided on GDM

Gestational diabetes

By Nicola Garrett

19 Feb 2015

Sparks have flown in the letters page of the MJA this week, with a leading endocrinologist slammed by his colleagues for failing to consider the benefits of an internationally agreed set of guidelines for diagnosing gestational diabetes.

In a debate article published in the MJA last year endocrinologist Michael d’Emden from the Royal Brisbane and Women’s Hospital in Brisbane called for a reassessment of the new lower diagnostic thresholds for gestational diabetes (GDM), calling them “statistically flawed” with room for improvement.

He cited two main problems with the criteria — the use of combined adverse neonatal outcomes and the effect of normal blood glucose levels (BGL) parameters on risk.

He suggested some minor amendments to the criteria would more accurately identify babies who were large for gestational age.

However Leonie Calloway, an obstetrician and President of the Australasian Diabetes in Pregnancy Society and endocrinologist Aidan McElduff say the article had not considered the value of an internationally agreed set of guidelines.

Such guidelines would allow for a consistent approach to the definition, and provide a consistent baseline to answer many of the unanswered questions, they wrote in a letter to the MJA.

“The benefit of an internationally agreed set of guidelines for the diagnosis of GDM cannot be undestated,” they said.

“The new guidelines have been carefully considered by the international community and are consistent with a large observational study and Level 1 evidence from two well conducted trials, with controversies raised by d’Emden debated for several years,” they wrote.

In response, D’Emden said his colleagues were dismissive of his concerns and had asserted “incorrectly” that his arguments were old.

The potential reduction of the risk of a birthweight in the 90th centile when one or more blood glucose levels on an oral glucose tolerance test are normal was only suggested in February 2014, he wrote in response.

In response new data confirmed the statistical flaw in the new diagnostic criteria, he said.

“These data showed that nearly 50% of women having only one elevated BGL test result do not reach the diagnostic risk threshold, and women having two or more BGL results just below the new diagnostic levels may be at greater risk, yet will not be identified”.

Australia has an opportunity to develop a better statistically valid, diagnostic approach, he said.

“The rate of GDM and its management can then be benchmarked against other countries that have adopted the new statistically flawed diagnostic criteria.”

“The benefit of this approach cannot be understated,” he wrote.

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