Hypoglycemia Due to the Presence of Anti-insulin Antibodies: A Case Report

ABSTRACT

A 50-year-old male was referred to our clinic for hypoglycemic attacks. He denied using oral antidiabetic drugs, insulin, or herbal substances but admitted using proton pump inhibitors, pregabalin, and alpha lipoic acid. Venous blood glucose level was 44 mg/dL, C-peptide was 15.6 ng/mL, and insulin levels were >1.000 μIU/mL. His BMI was 21.4. No evidence of pancreatic or extra pancreatic insulinoma was found in imaging studies. No diagnostic results were obtained in the selective calcium receptor stimulation test. Anti-insulin antibody test was positive. The insulin autoimmune syndrome was diagnosed with low glucose levels. The symptoms were associated with very high serum insulin levels, and the patient was positive for the anti-insulin antibody. Alpha lipoic acid and proton pump inhibitors, which may cause insulin autoimmune syndrome, were discontinued and alpha glucosidase inhibitor and diet therapy were started. During follow-up, the patient did not report hypoglycemia. Insulin autoimmune hypoglycemia should be kept in mind in patients with very high levels of insulin and without evidence of insulinoma.