Poster Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

Post-gastric bypass hyperinsulinaemic hypoglycaemia managed with bypass reversal (#424)

Joey Yeoh 1 , Geoff Braatvedt 1
  1. ADHB Endocrinology, Auckland, AUCKLAND, New Zealand

A 48-year-old Caucasian female presented two years following her Roux-en-Y gastric bypass (RYGB) with sympathoadrenal and neuroglycopaenic symptoms occurring two to four hours post-prandially at a frequency of three to five times weekly. Her pre-operative weight was 116 kg (BMI of 46.4 kg/m2) and she had achieved 31 kg of weight loss by the time of presentation.

She had a negative 20-hr overnight fast but a subsequent 5-hour Mixed Meal Test (MMT) resulted in symptomatic hypoglycaemia at 2.5 hours with serum insulin of 5.8 mIU/L (2.6 – 24.9) and C-peptide of 1300 pmol/L (370 – 1470). Multiphase Computed Tomography (CT) showed no lesions in her pancreas. Selective Arterial Calcium Stimulation Testing (SACST) demonstrated a 2.0-fold, 2.4-fold & 1.5-fold increase in plasma insulin respectively, following 0.00625 mEq calcium gluconate infusion into the gastroduodenal, proximal splenic and superior mesenteric arteries. This confirmed diffuse hyperstimulation of pancreatic β-cells and hence post-gastric bypass hyperinsulinaemic hypoglycaemia.

Low carbohydrate meals and pharmacotherapy were either of minimal efficacy (Acarbose, Octreotide, Prednisone) or not tolerated (Diazoxide). The frequency and severity of neuroglycopaenic symptoms worsened over 6 months and she finally underwent laparoscopic reversal of her RYGB. At 6 months post-reversal, the frequency of her hypoglycaemic episodes has reduced significantly (one episode every three to four weeks). Repeat MMT 6 months post-operatively demonstrated a nadir serum glucose of 2.2 mmol/L at 2.5 hours but serum insulin was appropriately suppressed at 2.6 mIU/L with C-Peptide at 636 pmol/L. She experienced mild dizziness which resolved in 5 minutes without any therapy.

Bypass reversal may be an alternative surgical option to pancreatectomy. However, a recent report of bypass reversal in two patients demonstrated no effect on hyperinsulinaemic hypoglycaemia [1]. Conversely, our case demonstrated significant biochemical and symptomatic improvement but the durability of such benefit remains uncertain and further prospective studies are needed.

  1. Lee CJ, Brown T, Magnuson TH, Egan JM, et al. Hormonal response to a mixed-meal challenge after reversal of gastric bypass for hypoglycemia. J Clin Endocrinol Metab 2013 Jul; 98(7):E1208-12.