Refractory diabetic ketoacidosis in Rabson–Mendenhall syndrome due to a novel mutation: contrasting outcomes in a sibling – case series

Abstract Objectives Rabson–Mendenhall syndrome (RMS) is a rare monogenic insulin resistance disorder characterized by progressive dysglycemia and early mortality. Management of diabetic ketoacidosis (DKA) in RMS is particularly challenging because standard insulin doses may be inadequate, and pediatric-specific experience is limited. Case presentation We report two siblings with genetically confirmed RMS. The index child, a 7-year-old girl, presented with severe refractory DKA requiring progressive escalation of intravenous insulin to 12 IU/kg/h before meaningful metabolic response was achieved. Insulin was titrated according to serial glycemic and acid–base responses, without bicarbonate therapy, with close potassium monitoring. Her 3-year-old brother was evaluated proactively after the diagnosis in his sister and was found to have hyperglycemia and the same homozygous INSR variant before an episode of metabolic decompensation. He was treated with subcutaneous insulin and insulin sensitizers. At 1-year follow-up, HbA 1c was 10.4 % in the index child and 8.9 % in the sibling. Conclusions Refractory DKA in RMS may require rapid, response-guided escalation of insulin beyond conventional pediatric dosing. The detailed temporal relationship between insulin dose and metabolic response in this child provides practical clinical insight, while early recognition of RMS permits evaluation and treatment of affected siblings before presentation with acute metabolic decompensation.