ation.
- 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 HAPO study used a very strict protocol for OGTT collection: blood was collected into fluoride tubes placed immediately on ice (which helped slow down the cells to stop them using glucose) and samples were processed within one hour of test completion. This is not practical in most clinical settings and is not done in WA.
We estimated the loss of glucose in OGTT samples collected into fluoride tubes and corrected glucose results had the HAPO study ice-method or fluoride-citrate (FC) Mix tubes been used. FC Mix tubes are used internationally because they stop glycolysis straight away and keep blood glucose results accurate over time, even at room-temperature. We found:
- Correction for glucose loss using the HAPO study ice-method more than doubled the rate of GDM (from 9.7% to 22.7%).
- FC tube correction gave slightly higher results compared to the HAPO study ice-method (+0.20 mmol/L) and quadrupled the rate of GDM (44.6%).
One in five women who probably had GDM but were not managed had a large baby. This is similar to the rate of women in the HAPO study who had GDM and had a large baby (16.2%, one in six).
- Correction for glucose loss using the HAPO study ice-method improved GDM prediction of risk for a large baby (from 1.1 to 1.8 relative risk compared to women without GDM).
- The higher risk for a large baby remained in women with GDM after accounting for weight, age and smoking.
- When using the FC Mix tube correction we needed to increase the GDM diagnostic criteria +0.20 mmol/L to get similar results to the HAPO study ice-method.
FC tubes are now in used in the Kimberley. We are using FC Mix tubes in Aboriginal Health Service clinics in the Kimberley that give more accurate glucose results, even if the blood sample takes a long time to reach the laboratory. We are monitoring the results of this change.
- Almost three-quarters (71.4%) of Aboriginal women with early HbA1c ≥5.6% went on to have a positive OGTT. We think these women had prediabetes going into pregnancy.
- There were clear differences between Abor