Poster Presentation Society of Obstetric Medicine of Australia and New Zealand ASM 2015

The Utility of Digital Blood Glucose Monitoring Metrics to Predict High Birth Weight in Women with Gestational Diabetes Mellitus (#121)

J E Hirst 1 , A J Farmer 2 , L Loerup 3 , L H MacKillop 1 4 , J C Levy 4 , K Bartlett 4 , Y M Kenworthy 1 , Dev A Kevat 1 5 , C Velardo 3 , L Tarassenko 3
  1. Nuffield Dept. Obstetrics & Gynaecology, University of Oxford, Oxford
  2. Nuffield Dept. of Primary Care Health Sciences, University of Oxford, Oxford
  3. Institute of Biomedical Engineering, Dept. of Engineering Science, University of Oxford, Oxford
  4. John Radcliffe Hospital, Oxford
  5. School of Public Health, Monash University, Melbourne, VIC, Australia

Quantifying blood glucose (BG) control in gestational diabetes mellitus (GDM) is difficult. Digital systems provide new metrics, yet clinical and research utility is not established. We aimed to determine utility of digital BG metrics as predictors for large for gestational age (LGA).

GDM screening was per 2008 National Institute of Clinical Excellence guidance (75g OGTT, positive if fasting BG >7.0mmol/L or 2 hour >7.8mmol/L) In women diagnosed with GDM, fasting, pre- and 2-hour post-prandial self-monitoring of BG was advised using a smartphone-based digital BG management system with regular clinician review. Mean total, fasting, postprandial BG and proportion of BGs over target were calculated (median duration of monitoring 9 weeks). Birth weight was classified as LGA (> 90th centile for gestation and gender) per INTERGROWTH-21st standards (Villar, 2014). Continuous variables were converted to z scores. Logistic regression was adjusted for parity and height.

Of 41 women, 12 had LGA babies (29%). The odds of LGA increased with every SD increase (0.7 mmol/L) in mean BG (aOR 3.2, 95% CI 1.1-9.6) and SD increase (0.9) in post-prandial BG (aOR 3.7,1.2-11.2), but not fasting BG (aOR 1.9, 0.8-4.7), SD (0.7). BG weekly moving averages were higher for LGA babies for the duration of monitoring. These associations justify further studies to validate potential uses for digital BG metrics.

  1. Villar et al, International standards for newborn weight, length, and head circumference by gestational age and sex: the Newborn Cross-Sectional Study of the INTERGROWTH-21st Project. Lancet. 2014 Sep 6;384(9946):857-68.