Oral Presentation Australasian Diabetes in Pregnancy Society Annual Scientific Meeting 2016

The Diagnosis of Gestational Diabetes Mellitus after Bariatric Surgery: Are we off target? (#7)

Eddy J Tabet 1 2 , Glynis P Ross 1 3 , Jeff R Flack 1 2 4
  1. Diabetes Centre, Bankstown-Lidcombe Hospital, Bankstown, NSW, Australia
  2. Faculty of Medicine, UNSW, Sydney, NSW, Australia
  3. Faculty of Medicine, University of Sydney, Sydney, NSW, Australia
  4. School of Medicine, Western Sydney University, Campbelltown , NSW, Australia

Background: Bariatric surgery (BS) is an effective treatment increasingly chosen by obese women seeking pregnancy. No guidelines exist for screening and diagnosis of GDM in women after BS. Oral glucose tolerance test (OGTT) profiles differ in BS patients, frequently resulting in reactive hypoglycaemia (1) and may not be tolerated. Hence the utility of the OGTT for GDM diagnosis after BS requires validation and reconsideration.

Aims:

  1. To determine from the literature what alternative methods (if any) for GDM diagnosis in BS patients have been used.
  2. To explore current approaches to GDM diagnosis in Australian women post BS by surveying diabetes centre members of NADC and ADIPS members.

Methods:

  1. A literature review identified 12 studies reporting GDM prevalence after BS. Each was assessed regarding GDM diagnostic criteria used.
  2. A one-page questionnaire was sent to NADC and ADIPS members to ascertain local experience in antenatal glucose tolerance assessment of BS-treated women exploring diagnostic methods and criteria used for GDM diagnosis.

Results:

  1. GDM data were mostly published following LAGB and RYGB (table 1). Over 50% of studies did not specify the criteria applied to diagnose GDM. Most studies that did, applied OGTT criteria equally for BS women and non-BS women.
  2. 15 surveys were returned Australia-wide (table 2). Although few BS cases were managed antenatally, LAGB was the procedure most commonly reported. Most sites use the OGTT and apply ADIPS criteria equally in women with/without a BS history.

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Conclusion:

Limitations of the OGTT in GDM diagnosis after BS are under-recognised. OGTT is still the most widely utilised diagnostic test in this context. Examples of alternatives include CGM (2), fasting and 2-hour post-prandial glucose levels (3), HbA1c (4) or a combination at 24-28 weeks gestation. These methods are yet to be tested in clinical trials or endorsed.

Acknowledgements:

We wish to thank the National Association of Diabetes Centres and the Australasian Diabetes in Pregnancy Society who emailed our questionnaire and a follow-up reminder to their members, and all those who responded.

  1. Roslin M, Oren J, Polan B. et al. Abnormal glucose tolerance testing after gastric bypass. Surgery for Obesity and Related Diseases 2013; 9: 26-31
  2. Woodard CB. Pregnancy following bariatric surgery. J Perinat Neonat. Nurs. 2004; 18(4): 329-40
  3. ACOG practice bulletin no. 105: bariatric surgery and pregnancy. Obstet Gynecol 2009: 113: 1405-13
  4. Wittgrove AC, Jester L, Wittgrove P et al. Obesity Surgery 1998; 8:461-464