Type B insulin resistance syndrome with systemic lupus erythematosus.

Type B insulin resistance syndrome is a rare disease. Auto-antibodies to the insulin receptor frequently appear in the case of systemic lupus erythematosus (SLE). We report herein a case of a 56-year-old man who had presented discoid skin lesions since 1990. He was admitted to the hospital because of unconsciousness and severe hypoglycemia in 2006, and was diagnosed as having Type B insulin resistance syndrome with the presence of insulin receptor antibody. He had frequently repeated hypoglycemic and hyperglycemic episodes in spite of treatment with prednisolone (5 - 10 mg/day), and mild proteinuria of 1.5 g/day was observed. His laboratory findings on admission revealed pancytopenia and positive titer for antinuclear antibody (ANA). From these findings and his past history of skin lesions, we diagnosed him as SLE. We performed renal biopsy and his histological diagnosis was lupus nephritis Class 5 with the findings of podocytic shedding. Prednisolone dosage was increased from 10 to 60 mg/day. Thereafter, his glucose metabolism improved and proteinuria disappeared. The dose of prednisolone was tapered to 30 mg/day without recurrence of hypoglycemia and proteinuria. Early treatment with prednisolone might ameliorate proteinuria and insulin resistance. We experienced a rare case of Type B insulin resistance syndrome with increased activity of SLE, complicated with lupus nephritis. It appears that Type B insulin resistance syndrome should be suspected in differential diagnosis of hypoglycemia in SLE patients.