One way of preventing the rising burden of diabetes globally is to focus attention early in life by addressing diabetes during pregnancy, also named gestational diabetes mellitus (GDM).
14 October 2013 Brit Larsen
Mapping the prevalence rate of GDM has two advantages: it gives a reflection of pre-diabetes (impaired glucose tolerance) – in young reproductive women, and it reflects the background prevalence of type 2 diabetes in the given population. In other words, detecting GDM may hold the key to reduce future diabetes.
A new consensus Hitherto, it has been difficult to map a global rate of GDM because different diagnostic criteria have been applied and has made it next to impossible to compare prevalence rates across countries. Different recommendations are made with different tests with either fasting, postprandial or both as requirements. Furthermore, different blood glucose thresholds as diagnostic criteria have been recommended. Yet, with the World Health Organization’s (WHO) recent endorsement of the new diagnostic criteria for screening for GDM consensus may have been reached. The new criteria still entail a number of challenges - particularly for low resource settings – but the advantages may outweigh the challenges.
The challenges in low resource settings In an article published in Global Health Action[1], PhD fellow, Karoline Kragelund Nielsen interviewed 10 of WDF’s project partners who are implementing projects and screening for GDM. One of the challenges she identified was that pregnant women often do not attend antenatal care as early as week 24-28 which is the recommended period for diagnosing GDM. Another broadly mentioned challenge is that patients need to show up fasting. In low resource settings transportation is a well-known barrier for attending health care and if – on top of a long distance – a woman has to omit eating it adds just another barrier. Finally, a third barrier is the scarcity of test consumables and lack of equipment to carry out the tests.
Different realities In her conclusion Kragelund Nielsen emphasises the need for a pragmatic approach to what can actually be achieved at the basic care level. Three WDF-project partners who work with GDM in Cameroon, India and China attest to different realities for diagnosing GDM in their respective settings.
Dr Eugene Sobngwi who has run a pilot project on gestational diabetes in Cameroon welcomes the new criteria. “The new criteria make things much simpler because the majority of cases will be diagnosed by only using the fasting blood glucose. The simple test is a huge advantage because it makes it easier to conduct at the antenatal clinic. Given the high workload there, the test has to be simple,” he says.
“Admittedly, it is also a barrier for us to have women coming in fasting, but the advantage of using a simple fasting glucose test [instead of OGTT] far outweighs the disadvantage of the fasting state of the women,” he says. Optimally, the new criteria recommend using fasting blood glucose combined with OGTT to diagnose GDM, but diagnosis based on one of these elements alone is also accepted. Implementing the new diagnostic criteria with lower threshold for the diagnosis of GDM the prevalence changes from previously 5% to now 17.5% in Cameroon.
The GDM prevalence rates change dramatically when using the new criteria: Cameroon: from 5% to 17,5%; India: from 11% to 32%; China: from 5% to 16%.
India: One third of all women could be stigmatisedAt Deep Hospital, Punjab in Northern India WDF project partner Dr Geeti Arora has a more sceptical take on the new criteria. First of all, she emphasises that diabetes remains a stigmatising diagnosis among Indian women. “Almost one third of pregnant women will have a diagnosis of GDM if the new criteria are fully implemented,” she says. “The majority of these are diagnosed based on fasting plasma glucose samples, and it is not known whether this will be feasible to implement all over India.”
“We have found that illiteracy is a very important risk factor of GDM in North India, exceeding the impact of age and BMI, and screening as well as subsequent treatment therefore needs to target the poorest segments of the population, many of whom are living in the less developed rural areas,” Dr Arora states.
Implementing the new criteria in Northern India will mean an increase of GDM prevalence from 11% to 32%.
At the Peking University First Hospital in China, the new diagnostic criteria have been used for the last two years. According to WDF project partner Prof Huixia Yang, the new criteria work well in a Chinese context. “We now diagnose more women and have experienced a dramatic increase in prevalence rates from around 5% to over 16%. This new high prevalence may turn out to have a positive effect on the future risk of mother and child as we capture many more and educate them in healthy lifestyle. And it enables us to distinguish between mild and severe cases of GDM. The 9 out of 10 mild cases can be treated with simple lifestyle education and then doctors can focus attention on the 1 out of 10 severe case of GDM which needs medication,” she says.
Merely a matter of trainingIn Cameroon, Dr Sobngwi echoes Dr Yang’s optimism. “Although the high prevalence of GDM increases the immediate workload of the health assistants I still think it is realistic for the antenatal clinic to manage. The resources are there; it is merely a matter of training of health assistants to deal with the 9 out of 10 cases which be managed by diet and exercise. We can definitely do training. We have already developed training material (English/French) and handed it over to the Ministry of Health. And the best part is the potential huge impact on the future health of mother and child,” he says.
The World Diabetes Foundation has played a catalysing role in bringing attention to GDM as an important factor to further the prevention of diabetes at primary care and policy level.
FACTSThe key element in the new diagnostic criteria is the one step challenge test. The test starts with a fasting blood glucose (BG) measurement followed by an oral glucose tolerance test (OGGT) after a 75 g oral glucose. Blood samples for BG measurements are taken after one and two hours.Diagnosis of gestational diabetes is made if one or more of the following criteria are met:fasting plasma glucose is 5.1-6.9 mmol/l1 hour plasma glucose is equal to or more than 10 mmol/l2 hour plasma glucose levels are between 8.5-11.0 mmol/lIf fasting plasma glucose is ≥7.0 mmol/l, or if 2 hour or random plasma glucose is ≥ 11.1 mmol/l a diagnosis of diabetes in pregnancy should be made.Applying some of the previous criteria with higher thresholds for diagnosis of GDM not all women at risk of complications have been captured according to data from the recent published HAPO study.
[1] Kragelund Nielsen et al. “The urgent need for universally applicable simple screening procedures and diagnostic criteria for gestational diabetes mellitus - lessons from projects funded by the World Diabetes Foundation.” Global Health Action, Vol 5 (2012).