Prolonged OGTT audit to assess for reactive hypoglycaemia

P Machenahalli, V Greener, D Morganstein, Chelsea and Westminster Hospital

Postprandial reactive hypoglycaemia is a descriptor of timing of hypoglycaemia. Defined as hypoglycaemia postprandially with blood glucose of <3.3mmol/L in association with sympathoadrenal symptoms which are corrected by glucose load. Postprandial hypoglycaemia may be defined as a transient event during conversion from the fed to the fasted state in which blood glucose levels fall sufficiently low to produce symptoms of hypoglycaemia.

Aim of the audit: To investigate the outcome of the prolonged oral glucose tolerance test for patients presented with clinical symptoms of reactive hypoglycaemia. To identify the type of bariatric surgery leading to more hypoglycaemia post-surgery.

Methods: We performed retrospective audit of the prolonged OGTT procedures performed from 2008 to August 2015. Data was collected from reported tests on the electronic patientsí database.Total of 69 patients had prolonged OGTT. Of these 17% (12) patients had bariatric surgery.

Non bariatric surgery patients: 57 patients had prolonged OGTT as they presented with symptoms of post prandial reactive hypoglycaemia. Of these 47% (27) were male and 53% (30) were female. 49% (28) patients experienced adrenergic symptoms, 31% (18) has neuroglycopenic, 3% (2) has both adrenergic and neuroglycopenic symptoms. 59% of the patients had blood glucose <3.3 mmol/l following prolonged OGTT, these patients have been given the diagnosis of reactive hypoglycaemia. They have been managed by low GI diet, metformin.

Post bariatric surgery patients: 12 patients following bariatric surgery had reactive hypoglycaemia and had Prolonged OGTT. Of these 10% (1) female and 90% (11) male.† 93% (11) of the patients had the diagnosis of reactive hypoglycaemia. 83% (10) gastric bypass surgery patients had reactive hypoglycaemia. One patient had fundoplication. ††††††††

Conclusion: 59% of the patients in non-bariatric surgery group had reactive hypoglycaemia. In bariatric surgery group of patients gastric bypass group experienced more hypoglycaemia.


1.    Evaluation and management of adult hypoglycemic disorders: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2009 Mar;94(3):709-28. doi: 10.1210/jc.2008-1410. Epub 2008 Dec 16