At aged 29 with secondary amenorrhea and symptomatic diabetes due to INSR autoantibodies. Lean with prominent hirsutism and acne. Bilateral bulky ovaries, stromal hyperplasia and proliferating immature follicles on MRI. Leuprorelin commenced; testosterone reduced by 75% after 2 months, insulin requirements remained high. Systemic lupus erythematosus diagnosed. Immunosuppressive therapy initiated with rapid improvement in glycemic control. Serum testosterone concentration normal after 24 months. The gene discussed is INSR; the disease is diabetes mellitus.