With gestational diabetes on the rise, a dramatic overhaul is needed

The increase in female obesity shown in the latest New Zealand Health Survey is a likely contributor to the growing numbers of women who develop gestational diabetes during pregnancy.

Thousands of New Zealand women develop this condition every year and the number of cases is likely to increase. It’s a global trend, most probably driven by rising rates of obesity and also by trends in women giving birth at an older age.

Many women only learn about gestational diabetes mellitus (GDM) when they get it, and some never even realise they have a condition that can serve as a harbinger for the future health of them and their child. Although it resolves after pregnancy in some women, for others it can persist or return as type 2 diabetes years later. About half of women with GDM will develop type 2 diabetes within 10 years of their GDM-affected pregnancy.

Improving care could have immense gains, as the condition brings elevated risks of type 2 diabetes for the mother, while infants face increased odds of low blood sugar levels after birth and type 2 diabetes, obesity and heart disease in later life, perpetuating the cycle. Women with a history of GDM face an almost 10-fold increased risk of developing type 2 diabetes after pregnancy compared with women without a GDM-affected pregnancy.

Because diet plays a critical role in treating gestational diabetes, with many women able to rely on dietary changes alone, big gains are within reach if we can improve awareness of the condition and access to advice from dietitians. GDM arises when an increase in pregnancy hormones blocks the action of insulin, leading to abnormally high blood sugar levels.

Excess sugar in the mother’s blood enters the baby’s bloodstream, fuelling excessive growth and stimulating extra insulin production which can then lead to dangerously low blood sugar levels in the baby after birth. Excessive growth can lead to a baby becoming large-for-gestational age, which can lead to complications such as trauma during birth, shoulder dystocia – where the size of the baby’s shoulders can impede the birth – or the need for a Caesarean section.

Many women with gestational diabetes have to book a C-section before their due date so the baby doesn’t get too big before natural labour.

Gestational diabetes affects at least six percent of pregnancies – about 3,800 per year – according to Liggins Institute research based on 2009 and 2010 data from the Growing Up in New Zealand study. It’s the largest research on the topic so far, but probably understates the scale of the problem today. There is very little national research on gestational diabetes – we don’t even have an accurate read on what the national level is. It’s highly likely a significant proportion of women go undiagnosed, and even with a diagnosis of gestational diabetes many do not receive an adequate level of care. A 2017 study in the Bay of Plenty found significantly fewer Māori women being screened for diabetes in pregnancy compared with other ethnicities.

What exactly causes gestational diabetes is unknown, but diet, lifestyle and genetics are all thought to play roles. Asian, Indian, Pacific and Māori women and women who are overweight or obese are all more at risk, while studies suggest eating fried foods and red and processed meats may also add to the chances of developing the disorder.

That diet plays a critical role in the management of gestational diabetes is undisputed. Internationally, health bodies recommend that all women with gestational diabetes see a dietitian for individually tailored dietary advice. However, our research, including interviews with women with gestational diabetes, suggests this doesn’t always happen in New Zealand.

Differences in the services provided are likely due to differences in funding allocation. Some district health boards fund up to three visits with a dietitian and others have funding for only one. The Ministry of Health collects data on gestational diabetes diagnoses from DHBs, but a recent study by Liggins researchers found that this information is likely to be inaccurate. Our research showed that many women diagnosed with gestational diabetes did not themselves report having the condition, raising questions about how the diagnosis was communicated and what treatment they received.

Liggins Institute interviews with women revealed that while some felt genuinely cared for and well supported during GDM pregnancies, others felt “just a number, another pregnant woman to get through”. With the prevalence of GDM on the rise and increasing pressure on the healthcare system, a dramatic overhaul is needed.

First we need to establish a robust system for monitoring the uptake of screening and its prevalence to address inequities in screening and funding allocation for gestational diabetes services. Further research should be conducted into the optimal model of care for such women to make the best use of available resources. Establishing healthy eating habits during pregnancy has the potential to have wide-reaching and long-lasting positive effects, not only for the mother but also her family and unborn baby through role-modelling.

Given the significant consequences of GDM and potential to improve the health of mothers and their families through optimal care, greater investment in the care of women with gestational diabetes has the potential to lead to significantly greater returns in the future.

Ideally, we would intervene even earlier, before pregnancy, to mitigate the risk of developing gestational diabetes in the first place but that requires a total shift in the health system towards preventative care. We should consider placing resources around the education of our teenagers and young adults concerning healthy eating to improve pregnancy outcomes in the next generation. The inter-pregnancy interval is another ideal opportunity, both for assessing whether gestational diabetes has fully resolved but also for dietary interventions to minimise the risk of the condition appearing in any subsequent pregnancies.