Overt diabetes in pregnancy: are they all the same? — ASN Events
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Overt diabetes in pregnancy: are they all the same? (#114)

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 3 , Sarah Abdo 1 4 , Jeff Flack 1 4 , Tang Wong 1 3 4
  1. Bankstown-Lidcombe Hospital, Chippendale, NSW, Australia
  2. Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
  3. School of Clinical Medicine, Faculty of Medicine and Health , UNSW, Sydney, NSW, Australia
  4. School of Medicine, Western Sydney University, Sydney, NSW, Australia

Background:

Overt diabetes in pregnancy (ODM) is associated with worse pregnancy outcomes compared with GDM. 

 

Aim:

To compare the risk of adverse pregnancy outcomes in 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 comprising ODM (n=660) and GDM (n=7658). ODM was subcategorised into FPG ≥ 7.0 mmol/L, 2-hr OGTT ≥11.1mmol/L, HbA1c ≥ 6.5%, or any combination of these.

Outcomes included insulin use, excessive weight gain (defined by Institute of Medicine criteria, using Asian‑specific BMI cut‑offs as per WHO guidelines), induction, Caesarean section, instrumental delivery, prematurity, large for gestational age, neonatal hypoglycaemia, jaundice and shoulder dystocia.

 

Results:

Of the 660 women with ODM, 79 had FPG ≥ 7.0 mmol/L, 358 had 2-hr OGTT ≥11.1mmol/L, and 105 had HbA1c ≥ 6.5%. 118 women had combination of raised FPG, 2-hr OGTT, and/or HbA1C.

Within the subgroups of ODM, those who were diagnosed with only abnormal 2-hr OGTT have less adverse pregnancy outcomes. There were similar rates of excessive weight gain, instrumental delivery, Caesarean section, induction, premature delivery, large for gestational age, and shoulder dystocia between GDM and ODM by 2h OGTT. This contrasts with the rest of the ODM subgroups, who had a higher proportion of women with excessive weight gain, Caesarean section, prematurity, large for gestational age, and shoulder dystocia compared to GDM. There were more neonatal hypoglycaemia and jaundice in ODM by 2h-OGTT and HbA1C compared to GDM. Insulin usage was higher in all ODM subgroups compared to GDM with the most in ODM by >1 criteria.

 

Conclusion:

ODM carries a higher risk of adverse pregnancy outcomes compared to GDM, but this varies by diagnostic criterion. FPG only, HbA1C only, and multi-criteria ODM confer the highest risk, likely reflecting sustained hyperglycaemia with greater fetal exposure. In contrast, isolated 2h-OGTT abnormalities may indicate more transient dysglycaemia and lower cumulative fetal exposure, potentially explaining fewer adverse pregnancy outcomes in this subgroup.