Abstract
RATIONALE: Insulin antibody-mediated insulin resistance is a rare autoimmune mechanism that can cause severe hyperglycemia. PATIENT CONCERNS: A 52-year-old male patient was admitted to our hospital with complaints of polydipsia, polyuria, and weight loss (8 kg in 6 months). He was diagnosed with type 2 diabetes mellitus at age 33. DIAGNOSES: Type 2 diabetes mellitus with antibody-mediated insulin resistance syndrome. INTERVENTIONS: Rituximab infusion in a 500 mg dose was given 2 times in a 2-week interval. OUTCOMES: A significant response was achieved 1 month later with fasting plasma glucose: 120 mg/dL (6.7 mmol/L), glycosylated hemoglobin A1c: 7.6% (59.6 mmol/mol), and anti-insulin antibodies: 0.001 U/mL. Clinically improved response persisted for about 6 months. LESSONS: Clinicians should be aware of the antibody-mediated insulin resistance, recognize suggestive signs and symptoms, pursue appropriate diagnostic evaluation, and treatment approach.