One size doesn’t fit all when it comes to screening of gestational diabetes in Denmark by the new WHO criteria
When Australian professor David McIntyre applied to the Danish Diabetes Academy for a visiting professorship a couple of years ago, one of his aims was to ‘find out how to introduce screening of gestational diabetes mellitus (GDM) in Denmark by the new WHO criteria’. He now knows that this is a bad idea. ‘“One size fits all” is not the solution’, he says today.
Together with researchers from Odense University Hospital, he has analysed data from the Odense Child Cohort and published the analysis in Diabetes Care. This has altered his view. Their conclusion is that ‘using FVPG ≥5.1 mmol/L for GDM diagnosis appears inappropriate for Denmark. It would classify an unmanageable number of women as having GDM who are at low absolute risk of pregnancy complications and divert finite health care resources from other areas. Although specific to Denmark, our data raise questions about uniform application of one set of GDM diagnostic thresholds across the world. For GDM diagnosis, “one size does not fit all”. Where possible, diagnostic thresholds should be adapted using local data’.
According to the study, the introduction of the new WHO screening recommendations will mean all 60,000 or so Danish pregnant women being screened, and 24,000 Danish pregnant women being treated for diabetes each year, instead of the 2,400 who are treated at present.
‘That makes no sense’, says Professor McIntyre.
But what is the solution, then?
‘To fund the SugarMum study developed by Tine and get some up-to-date information relevant to Denmark and then make a local “sensible” decision’, is his clear answer.
Tine is Tine Dalgaard Clausen, a clinical associate professor and consultant at the Department of Gynaecology and Obstetrics at North Zealand Hospital. She is currently raising funding for the SugarMum study, which may be of great importance for pregnant Danish women, their children and also for the health service’s finances. Read about the planned study in the article SugarMum to determine how best to tackle GDM in Denmark.
Possibly genetic – but not proven
David McIntyre cannot say for certain why Danish women’s risk of GDM is different to many others’. It may be genetic, but this is not proven, he says.
‘Danish women have higher average fasting glucose values during pregnancy. This appears to be true also for Danish people in general outside pregnancy. Exactly why is not certain. At the moment, GDM testing in Denmark does not include measurement of fasting glucose. Probably it should, but we would need to know the relevant (Danish) cut-off value’, he says.
David McIntyre points out that it is not only here in Denmark that the WHO recommendations will not work as intended – hence his recommendation to work on the basis of local data.
‘Some other places (e.g. India, Middle East) also have very high rates, but these run in parallel with high rates of type 2 diabetes outside pregnancy. Denmark is not a “high diabetes” country outside pregnancy, which makes very high rates of GDM hard to believe’, says David McIntyre.
Worldwide increase in hyperglycaemia
David McIntyre is very concerned at the prevalence of hyperglycaemia, which is increasing globally, with the two most obvious factors being increasing obesity and later child bearing. ‘The challenge is truly global, affecting over 20 million pregnancies each year, with 90 per cent of these mothers and babies being in low- and middle-income countries with very limited resources’, he says.
He points to the fact that hyperglycaemia has significant impacts in pregnancy, with effects on both mother and baby. ‘For the baby, there are risks of obesity and impaired glucose metabolism, which can lead to diabetes, plus risk of excess growth and increased risk of premature delivery and birth trauma. For the mothers, there is increased risk of hypertension and caesarean section. There is no one clear solution that fits this global problem, so the solutions need to be local and tailored to resources, local health care systems and the family setting’, he says – and hopes that the new study will be completed, so that Danish resources can be put to optimum use and both Danish mothers and their babies get the best possible treatment.
See the full study here:
Diabetes Care 2018 Jul; 41(7): 1339-1342. https://doi.org/10.2337/dc17-2393
David McIntyre is first author; the co-authors are Dorte M. Jensen, Richard C. Jensen, Henriette B. Kyhl, Tina K. Jensen, Dorte Glintborgand Marianne Andersen.
The data comes from the Odense Child Cohort, a prospective birth cohort following approximately 2,500 families from early pregnancy to the child’s 18th year. The aim is to provide new information about environmental, hereditary, social and biological factors influencing children’s health and wellbeing.
FACTS ABOUT GDM SCREENING
The WHO’s new criteria would mean all 60,000 or so pregnant Danish women being screened for gestational diabetes, whereas at present only 30-40% are screened for diabetes. These women are those at special risk because they have one or more of the following conditions: BMI above 27; family susceptibility to diabetes (first and second degree relatives); previous gestational diabetes; sugar in the urine; previous babies having weighed more than 4,500 grams at birth; twins; polycystic ovary syndrome.
More and more countries around the world are introducing the new WHO criteria. Worldwide recommendations (e.g. IADPSG / FIGO / ACOG / EBCOG ) are generally in favour of testing all women, but some other countries (e.g. the UK) still only test on the basis of ‘risk factors’, as in Denmark.
International data suggests that GDM treatment is definitely cost-effective if the cost saving of preventing diabetes in the mother post pregnancy is included. Costs of care, impact on pregnancy complications and cost and benefits of long-term follow-up probably vary widely between countries.
According to Professor David McIntyre, if an excessive number of women were diagnosed with gestational diabetes, the price would be that they would be ‘labelled’ as ‘abnormal’ and undergo additional testing, have more antenatal visits and perhaps risk more induction of labour and more caesarean sections, with no real evidence that they have any current risks that require extra treatment.
And for children whose mothers are not diagnosed with GDM in time, the price will be that they risk being more overweight / obese as they grow up (evidence by around age 10 but not always before) and also having higher rates of prediabetes and diabetes.
FACTS ABOUT PROFESSOR DAVID McINTYRE
Professor David McIntyre has been working in the field of endocrinology for more than 30 years. He is now Head of Mater Clinical School at the University of Queensland in Brisbane, Australia. As well as clinical practice, he has been involved in systems development in diabetes, endocrinology and medical disorders of pregnancy.
The primary aim of David McIntyre’s research collaboration during his visiting professorship in Denmark is improved recognition of, and care for, women with GDM in the Danish health care system. Professor David McIntyre collaborates with Professors Peter Damm and Elisabeth Mathiesen, University of Copenhagen, Professors Dorte Møller Jensen and Marianne Andersen, University of Southern Denmark and with Professor Per Ovesen, Aarhus University.
He is currently a member of:
Executive Committee, International Association of Diabetes in Pregnancy Study Groups; Pregnancy and Non Communicable Disease Committee, International Federation for Gynecology and Obstetrics (FIGO); Governing Board, Australasian Diabetes in Pregnancy Society.
The International Diabetes Federation 2019 Congress has selected him to provide the prestigious ‘Stream Award Lecture’ for Women’s Health and Diabetes at this year’s meeting from 2 to 6 December 2019 in Busan, Korea. His lecture will focus on Hyperglycaemia in Pregnancy and Women's Health in the 21st Century, because it is the commonest medical complication of pregnancy and affects around 10 to 15% of all pregnancies.
E: David.McIntyre@mater.org.au