Lesson of the Week: Addison's disease presenting as reduced insulin requirement in insulin dependent diabetes

Diagnosing Addison's disease requires a high degree of clinical suspicion since it is rare and its presenting symptoms are often non-specific. An association between Addison's disease and insulin dependent diabetes is well recognised. Whereas about 10-18% of patients with Addison's disease have insulin dependent diabetes, Addison's disease remains relatively rare among patients with insulin dependent diabetes.1 2 3 We report two cases of patients with previously well controlled diabetes presenting with recurrent severe hypoglycaemia despite reduction in insulin doses. A 43 year old man with a 15 year history of insulin dependent diabetes well controlled with a stable regimen of twice daily injections of human insulin was referred to the diabetic clinic, Royal Victoria Hospital, complaining of increased frequency of hypoglycaemic episodes on waking. On one occasion he required intramuscular glucagon administered by his wife. On a second occasion he collapsed at work and required medical assistance. He also complained of tiredness and nausea. He was advised to reduce his evening dose of long acting insulin and was given an appointment for further review. Before …