Poster Presentation Australasian Diabetes in Pregnancy Society Annual Scientific Meeting 2016

Gestational Diabetes Mellitus (GDM) diagnostic criteria: Is new better than old? (#121)

Hong Lin Evelyn Tan 1 , Judy Luu 1 2 , Amanda Caswell 2 3 , John Attia 2 , Shamasunder Acharya 1 2
  1. Department of Endocrinology and Diabetes, John Hunter Hospital, New Lambton, NSW, Australia
  2. School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia
  3. Hunter Medical Research Institute, Newcastle, NSW , Australia

Introduction: The diagnostic criteria for GDM have been widely debated, with questions surrounding complication prevention and resource strain. The John Hunter Hospital switched from high-risk to universal screening, and adopted the new GDM diagnostic criteria in 2014.

Hypothesis: Women with concordant oral glucose tolerance test (OGTT) results but discordant treatment status fulfilling former and new diagnostic criteria have different rates of birth complications.

Methods: Two OGTT datasets of pregnant women were collected at a single laboratory, for time periods 1/1/2009 to 31/6/2011(Old), and 1/4/2014 to 1/10/2015(New). Maternal data and perinatal outcomes were analysed with concordant positive OGTT women (Fasting Blood Glucose (FBG) ≥5.5 and 2hr glucose ≥8.5mmol/L) and discordant group (FBG 5.1-5.4 or 2hr glucose 8.0-8.4mmol/L).

Results: 262/2284 women were positive in the old criteria over 30 months (old timeframe), and 262/2897 women fulfilled new criteria over 18 months (new timeframe). The odds of any complication were significantly associated with concordant GDM positive women (OR 1.79, p=0.0002). There are increased odds of any complication for those with discordant treatment. Despite treatment, women with FBG 5.1-5.4mmol/L have thrice the odds of having macrosomia compared to those with 2hr glucose 8.1-8.4mmol/L (OR 3.03 p=0.06, and OR 0.75, p=0.74).

Conclusion: This study reflects clinical data with dual introduction of new GDM diagnostic criteria and universal screening. Although there has been an overall decrease in GDM diagnoses with universal screening, we have noticed a net increase in clinic patient load due to all pregnant women being screened. Fasting hyperglycaemia appears to predict macrosomia better in the new compared with former criteria. However in local practice, there has not been a significant benefit in outcomes with treatment of macrosomia. This may be in relation to obesity being a bigger contribution for fasting hyperglycaemia, or increased difficulty with attaining timely treatment targets.