IDF21-0025 Impact of different GDM diagnostic criteria on GDM incidence, therapy and postpartum dysglycemia in Malaysian women

Abstract

Background: Gestational-diabetes-mellitus (GDM) mothers are at increased risk of developing future prediabetes/T2DM. Risk of post-partum dysglycemia is proportionate to degree of antenatal hyperglycemia. Therefore, GDM diagnostic-criteria can impact post-partum dysglycemia incidence. Malaysia employs GDM diagnostic-criteria similar to the United-Kingdom which unlike the 2013 WHO (World Health Organization)-criteria, has a lower 2-hour threshold (7.8mmol/L). The UK 2015 NICE (National Institute for Health and Clinical Excellence)-criteria however utilize a higher fasting threshold 5.6 mmol/L compared with Malaysian and WHO criteria. Aim: To assess the impact of adopting 2013 WHO-criteria and 2015 NICE-criteria on GDM incidence, therapy and postpartum dysglycemia. Method: In this prospective observational study conducted in an urban centre in Malaysia, a multi-ethnic population of 1011 mothers underwent universal GDM screening with 75g OGTT (blood glucose evaluated at 0 and 2-hour, without 1-hour sample). Mothers were categorized into 4 groups: GDM by 2015 Malaysian-criteria (0-hour ≥ 5.1mmol/L and/or 2hr ≥ 7.8mmol/L), GDM by modified 2013 WHO-criteria(0-hour ≥ 5.1mmol/L and/or 2hr ≥ 8.5mmol/L), GDM reclassified as non-GDM by modified 2013 WHO-criteria(0-hour < 5.1mmol/L and 2hr 7.8-8.4mmol/L) and GDM reclassified as non-GDM by 2015 NICE-criteria (0-hour 5.1-5.5mmol/L and 2hr <7.8mmol/L). Glucose tolerance was re-evaluated within 1-year in those with GDM. Only mothers diagnosed by 2015 Malaysian-criteria were treated for GDM. Results: 65.8%, 23.3% and 9.5% of mothers were of Malay, Chinese and Indian ethnicity respectively. Use of the modified 2013 WHO-criteria reduced the overall GDM rate from 28.4% (n = 276) to 18.2% (n = 177) (p<0.05), with greatest reduction observed amongst Chinese women (35.2% to 19.8%) (p<0.05). 46.3% of Chinese women had mild post-challenge hyperglycemia (7.8-8.4mmol/L) and were thus missed using 2013-WHO cut-offs. Use of the NICE-criteria also reduced GDM incidence rate (28.4% to 23.3%) (p<0.05) with greatest decline in Indian mothers (33.7% to 20.7%) (p<0.05). Of the 88 women reclassified as non-GDM by modified 2013 WHO-criteria, 39.8% required pharmacological therapy for GDM. Despite receiving treatment, week-36 A1c was higher compared with normal-glucose-tolerance (NGT) mothers. 49 women (17.8%) would have been reclassified as non-GDM with NICE-criteria, 22.4% of whom required pharmacological therapy. 24.3% of GDM mothers diagnosed with Malaysian criteria (n = 67) had verifiable postpartum glycemic assessment within 1-year of delivery, 21 of whom had postpartum dysglycemia. Of those women with postpartum dysglycemia, 23.8% would have been reclassified as non-GDM by modified WHO-criteria and another 23.8% would have been reclassified as non-GDM by NICE-criteria. Discussion: Adoption of 2015 NICE-criteria, will reduce GDM incidence in Malaysian women, failing to identify women 1) requiring pharmacological intervention antenatally 2) at increased risk of postpartum-dysglycemia. Adoption of 2013 WHO-criteria without 1-hour glycemic assessment runs a similar risk. There may be ethnic variation in glycaemic risk-thresholds antenatally. Further larger studies with a 3-point OGTT are required to confirm these preliminary findings.