| Musings
Gestational Diabetes and Clinical Guidelines
For weeks, I have been knee-deep in gestational diabetes (GDM) and blood glucose evidence and literature, creating two lessons for the Collective. The Q&A sessions always include questions about diabetes, so I thought I'd cover the topic in depth because there is clearly a need for information. However, I was not prepared for the level of nonsense around this topic. My husband has been subjected to a number of exasperated rants. So, I thought I'd pick one to share with you!
The truth is there are risks associated with having abnormal blood glucose levels during pregnancy. By abnormal, I mean actually abnormal. Not the new lower thresholds based on non-diabetic blood glucose levels (see my blog post for more information on thresholds). The more significant risks (miscarriage, stillbirth, congenital abnormalities) are related to pre-existing diabetes and abnormal blood glucose levels in early pregnancy. Gestational diabetes, i.e. diabetes caused by pregnancy, occurs after 20 weeks, and the risks of abnormal blood glucose levels relate to birth and the postnatal period (eg. shoulder dystocia, hypoglycaemia, jaundice, polycythaemia). Not pregnancy loss.
However, women diagnosed with GDM continue to be told they have a higher risk of stillbirth if they do not control their blood glucose levels. The Queensland Health Guideline on Gestational Diabetes (with the cover by-line of 'translating evidence into best clinical practice') includes the following risk for GDM: 'Stillbirth (late) if GDM is uncontrolled or not treated resulting in raised fasting plasma glucose'. This statement directly contradicts research findings, including Cochrane reviews, and the guideline cites a UK study (Stacey et al. 2019) that does not apply to Australia. The UK uses risk-based screening, whereas Australia uses universal screening, and the study defined 'raised fasting plasma glucose' as ≥5.6 mmol/l, which is much higher than the Australian definition of ≥5.1 mmol/l. The study explored stillbirth risks associated with screening for women 'at risk' of GDM.
The study findings were the opposite of the statement made in the clinical guideline. Women diagnosed with GDM did not have an increased risk of stillbirth even if they had raised fasting plasma glucose. The increased rates of stillbirth occurred in the group of women 'at risk' of GDM who did not get tested i.e. a group of women who were more likely to have undetected pre-existing diabetes and other health risk factors. The study conclusion and recommendations support testing and diagnosis of women 'at risk' of GDM.
It is disappointing that clinical guidelines purporting to 'translate evidence into clincial practice', fail to cite appropriate research to support statements and recommendations. However, guidelines are created by working parties primarily made up of clinicians (not researchers) and often reinforce cultural norms and preferred practices rather than research evidence. So, I guess the moral of the story is don't rely on culture-based guidelines for evidence-based information. There are risks of having high blood glucose levels with uncontrolled GDM. Stillbirth is not one of those risks. |
