Fasting falls short in overt diabetes in pregnancy? — ASN Events
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Fasting falls short in overt diabetes in pregnancy? (#116)

Chih Ying (Maggie) Ko 1 2 , Ning Zhang 1 2 , Jenny Wright 1 , Stephanie Terry 1 , Cunjing Li 1 , Androulla Georgiou 1 , Mikey Xie 1 2 , Sarah Abdo 1 3 , Jeff Flack 1 3 , Tang Wong 1 2 3
  1. Bankstown-Lidcombe Hospital, Chippendale, NSW, Australia
  2. School of Clinical Medicine, Faculty of Medicine and Health , UNSW, Sydney, NSW, Australia
  3. School of Medicine, Western Sydney University, Sydney, NSW, Australia

Background:

Overt diabetes in pregnancy (ODM) confers increased risk of adverse pregnancy and neonatal outcomes compared to gestational diabetes (GDM), with rising global prevalence1–3. There are ethnic and geographical variations in prevalence and outcomes of ODM3.

 

Aim:

To explore impact of ethnicity on women with ODM based on fasting plasma glucose (FPG) ≥ 7.0 mmol/L, 2-hr oral glucose tolerance test (OGTT) ≥11.1mmol/L, HbA1c ≥ 6.5%, or any combination of these.

 

Methods:

We analysed prospectively collected data from singleton pregnancies between 1991-2025 in the South Western Sydney Local Health District comprising ODM (n=660) and GDM (n=7658). ODM was classified as those with FPG ≥ 7.0 mmol/L, 2-hr OGTT ≥11.1mmol/L, and/or HbA1c ≥ 6.5%4. Women with ODM were subcategorised into those diagnosed solely by FBG, 2-hr OGTT, HbA1c, or any combination of these.

 

Results:

Major ethnicities in ODM women were - East/Southeast Asian(n=165), South-Asian(n=146), Middle-Eastern(n=157), and European(n=129). There was an over-representation of South Asian women in ODM vs GDM (22.1% vs 15.5%, p<0.001).  Within ethnicities, the 2-hr OGTT identified the majority of overt cases across all groups. Between ethnicities, more East/Southeast Asians (71.5%,p<0.0001vsEuropean) and South Asians (66.4%,p<0.01vsEuropean) were diagnosed on 2h-OGTT, compared with Middle-Eastern (45.2%,p=NS vsEuropean) and European (47.3%,reference) women. In contrast, FPG identified relatively few cases, particularly among East/Southeast Asians (4.8% p<0.01vsEuropean) and South Asians (6.8% p<0.01vsEuropean), with somewhat higher proportions in Middle Eastern (17.2%,p=NS vsEuropean) and European (16.3%,reference) groups. Detection by HbA1c was more consistent across groups, ranging from 12.1% in Middle-Eastern participants to 18.6% in Europeans. Notably, the proportion of cases identified by more than one diagnostic criterion was highest in the Middle-Eastern group (25.5%,p<0.05vsEuropean), followed by Europeans (17.8%,reference), South Asians (13.7% p=NSvsEuropean), and East/Southeast Asians (10.9% p=NSvsEuropean). These findings demonstrate marked ethnic variation in diagnostic yield, with 2-hr OGTT identifying substantially more cases than FPG or HbA1c, particularly among Asian populations.

 

Conclusions:

South-Asian women are over-represented in ODM. ODM detection also varies significantly by ethnicity, with 2-hr OGTT identifying the majority of cases—particularly among Asian populations—while FPG underperforms. These findings support the ongoing use of 2-hr OGTT to improve diagnostic accuracy in diverse populations.