Ketotic Hypoglycaemia Following Sleeve Gastrectomy

Post-bariatric surgery hypoglycaemia is typically mediated by hyperinsulinaemia, although the exact mechanisms are incompletely understood. Two cases of non-insulin mediated, ketotic hypoglycaemia following sleeve gastrectomy are presented. After fasting for 40 and 65 h, respectively, both patients developed symptomatic hypoglycaemia, with corresponding low insulin, low c-peptide and elevated beta-hydroxybutyrate levels. Morning cortisol and IGF1 levels were normal. Potential mechanisms for ketotic hypoglycaemia following bariatric surgery include reduction in hepatic, renal and intestinal gluconeogenesis, or alternatively an underlying inborn error of metabolism such as a glycogen storage disorder unmasked by bariatric surgery. Most glycogen storage disorders present in childhood, but there have been rare case reports of glycogen storage disorders types I, III and IX diagnosed in adulthood. Neither of the above cases had other features of a glycogen storage disorder such as elevated lactate, hyperuricaemia, hypertriglyceridaemia, hepatomegaly, myopathy or an indicative family history. Both patients trialled first-line dietary management, which was inadequate in managing hypoglycaemia. Treatment with the glucagon-like peptide-1 receptor agonist semaglutide resulted in the resolution of hypoglycaemic episodes in one patient, and a significant reduction in hypoglycaemic episodes in the other patient.