Gestational diabetes

Gestational diabetes treatment controversy simmers on

Endocrinologists are being challenged by obstetricians and midwives who claim that the push to treat gestational diabetes mellitus is leading to overmedicalisation of pregnancy and the use of diabetes medications in pregnancy without a good evidence base.

The long-running controversy has been revived in an opinion paper published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, in which Queensland physician Dr Chris Hegarty raises concerns about a doubling in rate of GDM diagnosis in pregnancy from 7% to 14% between 2012 and 2017 following the adoption of more liberal IASDP diagnostic criteria. During the same time the number of women being treated with diabetes medication in pregnancy has also more than doubled from 1279 to 2972.

In his article, Dr Hegarty argues that the adverse consequences of  the GDM ‘epidemic’ have been overstated, with GDM babies on average about 100–200 g heavier and accounting for only a small number of macrosomic babies.

Conversely, he asserts that the benefits from drug treatment of GDM with agents such as metformin are much less than is generally believed. He says that aside from reducing birthweight by about 100g, treatment of GDM has not been shown to have a significant effect on important pregnancy outcomes.

“A diagnosis of GDM medicalises a normal pregnancy, moves care away from GPs or midwives into the hospital system, triggers interventions such as labour induction, and requires many rural women to have their babies in regional hospitals far from home. Mothers may experience anxiety and a loss of normality and personal control, more so if put on medication,” he writes.

“While few babies can benefit, all babies treated, particularly pharmacologically, are exposed to potential harm … all treated babies have their growth and lean mass reduced, which may be detrimental, particularly as the majority are already of normal or small size,” he adds.

Dr Hegarty concludes that as a precautionary principle the use of drugs should be avoided and preference given to lifestyle measures to treat GDM until further evidence is available.

“The pharmacological intensification of treatment is not based on sound evidence, is probably unnecessary, potentially harmful, and should be ceased until there is better evidence for benefit and safety,” he says.

The article has triggered further debate online with some healthcare workers claiming that it  “echoes the concerns of many midwives, obstetricians and others about the diagnosis and treatment of gestational diabetes.”

But in a response published this month, Sydney endocrinologist Professor David Simmons counters that the article ignores the rising incidence of metabolic disorders in women and is incorrect to claim there is no sound evidence for pharmacological treatment of GDM.

Professor Simmons past president of the Australasian Diabetes in Pregnancy Society (ADIPS), says GDM is a well defined condition and there is good evidence from a meta‐analysis of trials such as trials such as ACHOIS (Australian Carbohydrate Intolerance Study in Pregnant Women) showing major reductions in gestational hypertension and shoulder dystocia.

“With clear RCT evidence showing benefit from the stepped approach to GDM management, it would be unethical to withhold pharmacotherapy from women,” he writes

He says RCTs are needed of glycaemic thresholds for pharmacotherapy (based upon blood glucose monitoring) and of the impact of GDM treatment from the beginning of pregnancy, where only limited RCT evidence exists to guide clinical practice. One such study (the Treatment of Booking Gestational Diabetes Mellitus (TOBOGM) is underway in Australia and these will help with the development of new guidelines for GDM management, he suggests.

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