Endocrine Abstracts

Introduction

Insulin autoimmune syndrome (IAS), is rare cause of hyper-insulinemic hypoglycemia due to production of autoantibodies against the endogenous insulin in persons not formerly received insulin with no evidence of pancreatic lesions. Most described cases were in Asian peoples and this is the first case reported from Egypt.

Case report

A 64-year-old Egyptian female presented with repeated postprandial hypoglycemic attacks, approximately three hours after food ingestion, which improved on ingesting sweets. On one occasion, the patient lost her consciousness and was transferred to the nearest hospital where her plasma glucose was 26 mg/dl and she regained her consciousness after IV Dextrose 25%. Then, she was referred to our department for further assessment. She has no past history of chronic illness, nor family history of similar condition. She denied insulin or oral hypoglycemic drugs intake. Dietary history showed high intake of simple carbohydrates to overcome her frequent hypoglycemia. On physical examination: she was an obese female with BMI 38.9 kg/m², blood pressure 125/70 mmHg and heart rate 84/min with no signs of insulin resistance and her chest, abdomen, cardiac and neurological examination was unremarkable. Laboratory findings, including liver, kidney, adrenal, thyroid and glycemic profile were all normal except for elevated HbA1c (was 6.2%) and IGT (2-hpp glucose 186 mg/dl). She underwent prolonged (180-min) oral glucose tolerance test (OGTT) using 75 gm glucose. The patient began to develop hypoglycemic symptoms at 180-min of OGTT, during which her simultaneous plasma glucose was 49 mg/dl, serum Insulin > 1000 µiu/ml and C-peptide 17.22 ng/ml. These results were consistent with hyper-insulinemic hypoglycemia. Serum sulfonylurea drug screen was negative. Contrast-Enhanced triphasic CT abdomen was unremarkable with no evident of any pancreatic lesions. anti-insulin autoantibodies were found to be extremely high (> 100 u/ml). thus, the diagnosis of IAS was established. The patient was instructed to eat small frequent meals of low glycemic index. azathioprine 50 mg twice daily plus Prednisolone 60 mg were commenced. Her hypoglycemic attacks had completely subsided after two months of therapy, then the prednisolone dose was reduced gradually over the next three months with no recurrence of hypoglycemia, and repeated serum insulin and insulin antibodies showed a continual decline and her insulin autoantibodies became negative after 3 months of therapy.

Conclusion

IAS should be considered in any patient with hyperinsulinemic hypoglycemia, particularly if no detectable pancreatic or extrapancreatic neoplasm.