Oral Presentation Australasian Diabetes in Pregnancy Society Annual Scientific Meeting 2016

Testing for gestational diabetes mellitus with self-monitored blood glucose levels in women who have hypoglycaemia on oral glucose tolerance testing during pregnancy (#20)

Lili Yuen 1 , Hamish D Russell 1
  1. Diabetes & Endocrine Service, Liverpool Hospital, Liverpool, NSW, Australia

Introduction

The 75g oral glucose tolerance test (OGTT) is used in pregnancy to diagnose gestational diabetes mellitus (GDM). Results below reference range at 2 hours (<3.5mmol/L) could indicate supersensitivity to insulin1 and/or a delayed second stage release of insulin2, both of which are pathognomonic of impaired glucose tolerance. Whether these women may have undiagnosed GDM is unknown.

Objective

We sought to investigate whether women who experience hypoglycaemia on routine OGTT without meeting the recognised diagnostic cut-offs have evidence of GDM based on self-monitoring of blood glucose levels (SMBG).

Method

Between March 2015 to May 2016 we identified pregnant women attending Liverpool Hospital antenatal clinic who experienced hypoglycaemia on routine OGTT screening. These women were asked to perform 14 days of SMBG. We classified women as having GDM if they had >20% of capillary blood glucose levels (BGL) above targets suggested by the Australian Diabetes in Pregnancy Society (ADIPS)3, and the current4 and past South Western Sydney Local Health District (SWSLHD) guidelines.

Results

46 out of 60 identified women performed SMBG. Of these 46 women, mean age was 29.9 (SD+5.4), The women were predominantly of Caucasian (21 women or 46%) or Middle Eastern (15 women or 33%) ethnicity. The mean HbA1c was 4.8% (SD±0.96), pre-pregnancy BMI 25.9 (SD±5.5). 19 women (41%) had a family history of diabetes and 2 (4%) had previous history of GDM. 15 women (33%) were diagnosed with GDM based on elevated SMBG levels according to the ADIPS, 6 (13%) current SWSLHD and 3 (7%) past SWSLHD targets. Fasting BGLs were the most commonly elevated BGLs.

Conclusion

A significant proportion of women who have hypoglycaemia on screening OGTT have GDM based on elevated SMBG levels particularly using the ADIPS targets. Without further testing these women may be at risk of the complications of undiagnosed GDM.

  1. Sugiyama S, Jinnouchi H, Hieshima K, Jinnouchi T. Insulin supersensitivity and normoinsulinaemic hypoglycaemia in uncontrolled type 2 diabetes mellitus: clinical usefulness of 3 h assessment in the 75 g oral glucose tolerance test. BMJ Case Rep 2014;2014.
  2. Weissman A, Solt I, Zloczower M, Jakobi P. Hypoglycemia during the 100-g oral glucose tolerance test: incidence and perinatal significance. Obstet Gynecol 2005;105:1424-8.
  3. Nankervis A, McIntyre H, Moses R, Ross G, Callaway L, Porter C, et al. ADIPS consensus guidelines for the testing and diagnosis of gestational diabetes mellitus in Australia and New Zealand. 2014. Available from: http://adips.org/downloads/ADIPSConsensusGuidelinesGDM-03.05.13VersionACCEPTEDFINAL.pdf
  4. SWSLHD Policy No.: SWSLHD_PD2016_007 “Maternity – Gestational Diabetes Mellitus (GDM) Screening”. Downloaded from SWSLHD intranet: http://intranet.sswahs.nsw.gov.au/sswpolicies/pdf/swslhd/swslhd_pd2016_007.pdf