1) In the last paragraph we stated that patients with this condition have low circulating insulin, C-peptide levels, and refractory hypoglycemia. In this sentence, we did not describe our patient, but rather autoimmune hypoglycemia with insulin receptor antibody. Patients with anti-insulin antibody have high total insulin, low or normal free insulin, and low C-peptide levels (3). But a few cases had high C-peptide levels (4,5). Large amount of serum C-peptide may express an overproduction of proinsulin synthesis in the pancreas (4). Our patient had high total insulin and C-peptide levels.
2) In hypoglycemia due to insulin receptor antibodies, insulin levels are usually high. High C-peptide levels raise the possibility of a pancreatic tumor, for example, insulinoma. We thought that the possibility of an insulinoma was very low. Imaging studies were done, including magnetic resonance imaging scan, octreotide scan, computed tomography, arterial portography, and mesenteric aortography. Imaging studies showed nonspecific findings. The most important laboratory test in the differential diagnosis is a direct assay for the presence of antibodies directed against the insulin and it’s receptor (6). Our patient had anti-insulin and insulin receptor antibodies.