Endocrine Abstracts

Post-prandial hypoglycaemia (PPH) can be associated with debilitating symptoms. Causes include altered physiology post-bariatric and upper gastrointestinal (GI) surgery and rarely noninsulinoma pancreatogenous hypoglycemia syndrome and insulin antibodies. We present a case of 49y female with no prior GI surgery presenting with debilitating hypoglycaemia with blood glucose falling to 2.8 mmol/l responding to glucose. Freestyle Libre monitoring confirmed hypoglycaemia 2-3 h post meals in keeping with PPH. BMI- 30.3, HbA1c-47 mmol/mol, am cortisol-462 nmol/l. The usual dietary recommendations were difficult to implement due to xerostomia in Sjogren’s syndrome (SS) requiring mashed diet with fluids increasing diet’s glycaemic index and GI transit. Patient also had autoimmune neuromyotonia presenting with muscular twitching and cramping responding well to regular plasma exchange (PLEX) sessions. Interestingly, patient observed improvement in intensity and frequency of her hypoglycaemia after PLEX raising a possibility of autoimmune cause. We postulated that PLEX might have either somehow improved her GI mobility by alleviating neuromyotonia or removed other untested antibodies involved in autoimmune hypoglycaemia (TTG IgA, insulin antibodies or insulin receptor antibodies). Although she did not have typical GI symptoms apart from mild bloating, TTG IgA were positive at 46.2 u/ml (0-15), endomysial antibodies negative. Duodenal biopsies showed increased intraepithelial lymphocytes, but no definite villous blunting confirming coeliac disease (CD). Gluten free diet (GFD) was commenced with a complete and sustained resolution of hypoglycaemia. Patient described GFD effect on her hypoglycaemic symptoms and quality of life as life changing.

Discussion: CD should be considered in work up of PPH especially in patients with other concurrent autoimmune diagnoses. CD can lead to reduced GI glucose absorption, but the exact mechanism of PPH in our case was intriguing. Concurrent mechanisms such as gut dysmotility in neuromyotonia, diet in Sjogren’s syndrome and possibly presence of untested insulin antibodies might have compounded presentation in our case. Neuromyotonia presents with muscle cramps due to peripheral nerve hyperexcitability mainly affecting limbs and trunk. However, it has been reported that autonomic nervous system can also rarely be affected, which may present with gut dysmotility or excessive sweating. Testing for antibodies to insulin or insulin receptor was considered after hypoglycaemia response to plasmapheresis but was deferred given her complete response to GFD. Antibodies to insulin bind insulin after its postprandial secretion and subsequently release it independently of glycemia, predisposing to hypoglycaemia. Autoantibodies to the insulin receptor typically cause severe insulin resistance, but rarely they can also cause hypoglycaemia.