Developing algorithms to improve predicting the development of and screening for hyperglycaemia in pregnancy in rural communities
Gestational diabetes mellitus (GDM) is impaired glucose tolerance first detected in pregnancy. GDM is associated with a range of adverse neonatal and maternal outcomes. GDM is the commonest maternal antenatal abnormality in Australia. Screening is conducted in order to detect women at risk of disease, facilitating earlier management and treatment. Currently available evidence indicates that treatment of GDM with dietary modifications, glucose monitoring, and metformin and insulin (if needed) can significantly reduce the risk for adverse birth outcomes.
Current screening recommendations are for all pregnant women who are not known to have diabetes or GDM to have an oral glucose tolerance test (OGTT) at 24-28 weeks gestation. Women need to be fasted for this test and blood samples are taken immediately prior to consumption of a 75g glucose drink, and 1 and 2 hours later. Many women decline screening.
Alternative methods for diagnosing GDM or alternative methods for screening that lead to a reduction in the number of OGTTs required need to be found if we are to improve screening rates. We want to see if levels of glycation products such as HbA1c at first and third trimester antenatal visit predict the risk of developing GDM later in pregnancy or can be used instead of OGTT where an OGTT is difficult to achieve or refused by the patient.
The aims of this project are:
- To determine at baseline the number of 24-28 week OGTTs completed on at least 100 antenatal patients in each study region expected to have had an OGTT.
- To determine the relationship between first trimester antenatal information, including glycation products such as HbA1c, blood sugar levels, family history, obesity, maternal age, ethnic background, and 24-28 week glycation products, with 24-28 week OGTT.
- To determine the proportion of women enrolled in the study requiring an OGTT who complete the OGTT at 24-28 weeks gestation.
- To increase research interest and capacity among health service and RCSWA staff and students, and to build skills in rural and remote health service research.
To ensure that the project findings are generalisable to the broader regional, remote primary health care environment, it will be carried out in a range of health care services across Western Australia: Kimberley, Southwest, Greater South, Midwest and Goldfields.
This project is a collaboration between The Rural Clinical School of WA, KAMS, WA Country Health Services – Kimberley. We thank all partner health services for their significant in-kind contributions. This study is funded through grants from:
Progress to so far:
Many rural and remote Australian women are not tested for GDM. We looked at the antenatal records of 551 pregnant women, 16 years and older and without pre-existing diabetes from across rural and remote WA (Goldfields, Great Southern, Kimberley, Mid West and Southwest) who delivered in 2013. We found that:
- Only half the women were getting the OGTT done. It is meant to be all of them.
- Aboriginal women were less likely to have the OGTT done but more likely to have other blood glucose tests done.
- Some women had other, easier tests done instead of an OGTT.
- One fifth of rural WA women had no testing done.
In women who are tested we estimate 62% of GDM is missed due to OGTT sample instability. We recruited 600 women from across rural and remote WA between 2015 and 2018 who were amenable to having an OGTT; 501 had an OGTT after 24-weeks gestation. During the study we identified problems with OGTT sample stability:
- Cells inside blood samples continue to convert glucose into energy long after collection causing glucose levels to drop.
- In WA, tubes used to measure blood glucose contain fluoride to stop glucose loss, but are slow to work, taking 4-hours to stabilise glucose in the sample.
- The criteria that we use to diagnose GDM are based on the large international Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) study. The H