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.