[Hypoglycemia due to antibodies to exogenous insulin in a patient with type 2 diabetes – a case report of treatment with new generation oral hypoglycemic agents]

Abstract

Hypoglycemic syndromes associated with immune reactions against insulin are rare phenomena described predominantly in Asians. Steroid therapy, immunosuppression or plasmapheresis is often required.

Case report: A 73-year-old White woman with a 20-year history of type 2 diabetes was admitted to hospital due to recurrent incidents of hypoglycemia that started several months after insulin initiation (lispro 75/25) and increased in severity over the next 5 years. They were accompanied by postprandial hyperglycemia up to 25 mmol/l. The patient’s glycated hemoglobin (HbA1c) was 70 mmol/ mol (8.6%). During hypoglycemic episodes recorded serum C-peptide was 0.57-0.73 nmol/l (1.7-2.2 ng/ml), while insulin concentration exceeded 7000 pmol/l (1000 mIU/l). Surreptitious insulin administration was ruled out as was, based on diagnostic imaging, the presence of an insulin secreting tumor. Anti-insulin antibody (AIA) level measured by 125I-insulin binding method was 92.5% (normal < 8.2%). Hypoglycemic episodes occurred for four days after discontinuation of insulin therapy and then resolved completely. Good glycemic control was maintained with metformin, acarbose and dapagliflozin. Three months later dapagliflozin was replaced with vildagliptine due to poor tolerance of a SGLT-2 inhibitor. Patient’s HbA1c was 54 mmol/mol (7.1%), total fasting insulin level 2577 pmol/l and AIA binding 85.9%. Over the next year the patient has not experienced hypoglycemia and maintained good glycemic control, as HbA1c level was 53 mmol/l (7.0%) and AIA binding 39.5%.

Conclusions: In this rare case of a patient with diabetes and hypoglycemic syndrome related to AIA, we achieved a rapid and stable remission of hypoglycemia without immunosuppression. Good glycemic control, despite 20-year history of diabetes was achieved with oral hypoglycemic agents.