E-Poster 63rd Endocrine Society of Australia Annual Scientific Meeting 2020

Glucose Tolerance Test Induced Hypoglycaemia (#79)

Veli Kiriakova 1 , John Burgess 1 2
  1. Royal Hobart Hospital, Hobart, TAS, Australia
  2. School of Medicine, University of Tasmania, Hobart, TAS, Australia

Background

The 75g oral glucose tolerance test (OGTT) is routinely used to screen for Gestational Diabetes Mellitus (GDM) and to diagnose Diabetes Mellitus (DM) and impaired glucose tolerance (1,2). Some patients develop biochemical hypoglycaemia during the OGTT (3), the significance of which is unclear. Potential mechanisms leading to hypoglycaemia include Beta cell dysfunction with increased insulin secretion relative to insulin resistance (4). There is, however, a paucity of information regarding the long-term prognosis of patients experiencing hypoglycaemia during OGTT.

Aim

To investigate the incidence, aetiology and outcomes for hypoglycaemia during OGTT.

Methods

Data was obtained from all patients (18-80yo) who underwent an OGTT at the Royal Hobart Hospital (1996-2017). Patients experiencing biochemical hypoglycaemia were identified and hospital medical records were interrogated to determine the long-term outcomes for these patients.

Results

A total of 10559 separate OGTT tests were assessed for biochemical hypoglycaemia (£ 3.9mmol/L) at 0hr, 1hr or 2hr. Most patients were female (n=9913, 93.9%) and 6632 (62.8%) of referrals for OGTT were in the context of antenatal care. Findings revealed 654 (6.2%) of OGTT episodes were associated with a 2hr Blood Glucose Level (BGL) of £ 3.9mmol/L (mean 3.4mmol/L, SD 0.5), with 150 (1.4%) having a 2hr BGL of £3.0mmol/L (mean 2.3mmol/L, SD 0.3). Of these patients 106 (70.7%) were antenatal. Patient with hypoglycaemia £3.0mmol/L (n=143) were examined further. Five were ultimately diagnosed with diabetes mellitus and eight were deceased.  None were diagnosed with an insulinoma. Seven patients had further episodes of hypoglycaemia (2hr BGL £3.0) during subsequent OGTT. All of these were in the context of antenatal care. Four patients were found to have a 1hr and 2hr BGL £3.0, one was postpartum and breastfeeding, none were found to have an insulinoma. No patients with a 0hr (n=9) or 1hr (n=23) BGL £3.0mmol/L were diagnosed with DM or had an insulinoma.

Conclusion

Moderate to severe hypoglycaemia during OGTT is an infrequent but important response to OGTT. Our results show that hypoglycaemia is not commonly associated with any serious morbidity or underlying pathology, such as the development of diabetes mellitus or diagnosis of insulinoma.

  1. Nankervis, A., McIntyre, H.D., Moses, R., Ross, G.P., Callaway, L., Porter, C., et al., 2014. ADIPS consensus guidelines for the testing and diagnosis of gestational diabetes mellitus in Australia. Modified June.
  2. Welborn, T.A., 1996. ADS Position Statements: Screening for Non‐Insulin Dependent Diabetes.
  3. Parekh, S., Bodicoat, D.H., Brady, E., Webb, D., Mani, H., Mostafa, S., et al., 2014. Clinical characteristics of people experiencing biochemical hypoglycaemia during an oral glucose tolerance test: cross-sectional analyses from a UK multi-ethnic population. Diabetes research and clinical practice, 104(3), pp.427-434.
  4. Cai, X., Han, X., Zhou, X., Zhou, L., Zhang, S. and Ji, L., 2017. Associated factors with biochemical hypoglycemia during an oral glucose tolerance test in a Chinese population. Journal of Diabetes Research, 2017.