Severe Insulin Resistance Due To C.576CG (P.I119M) Mutation In The Insr Gene: Case Report

Objective: Severe insulin resistance is frequently associated with mutations in insulin signaling. Methods: We report here a 26-year-old woman with severe insulin resistance due to insulin receptorpathy. Results: This patient had asymptomatic hyperglycemia (hemoglobin A1c >10% [86 mmol/mol]), hyperinsulinemia, amenorrhea, hyperandrogenism, clitromegaly, loss of subcutaneous fat in the upper arms and thighs, and swelling in the hands and legs. Her body mass index was 19.8 kg/m 2 . Her adiponectin level was the highest ever reported by the laboratory (98.0 μg/mL). Her hyperglycemia was not associated with ketoacidosis, neuropathy, nephropathy, retinopathy, or vasculopathy. She was equally well with and without insulin therapy. She improved on metformin and drospirenone/ethinyl estradiol. Insulin receptor gene sequencing revealed a homozygous missense mutation in exon 2 (c.576C>G [p.I119M]). Conclusion: The clinical course illustrates a rare form of severe insulin resistance and its management challenges. Abbreviations: IGF-I = insulin-like growth factor I; IGFBP = IGF-I binding protein; INSR = insulin receptor; OCP = oral contraceptive pills; PCOS = polycystic ovary syndrome; rhIGF-I = recombinant human IGF-I