Idiopathic Addisons disease is characterised by the presence of adrenal antibodies and a documented variable subclinical period. In previously well controlled Type 1 diabetes, it may present with recurrent hypoglycaemia, or worsening erratic glycaemic control.
A 24 year old with previously well controlled Type 1 diabetes since age 18 months presented with worsening glycaemic control, 2 stone weight loss, frequent hypoglycaemia, postural hypotension and fainting. Primary hypothyroidism had been diagnosed and treated in 1995. She was thin and had a 20mmHg postural drop in blood pressure, but no hyperpigmentation. Thyroid, renal and liver function were normal , serum sodium 130, and serum potassium 5.2 millimoles per litre. Anti gliadin and antiendomysial antibodies were negative. A 250 microgram short synacthen test performed four months after presentation which was normal (basal cortisol 353 nanomoles per litre, 30min cortisol 599 nanomoles per litre, 60min cortisol nanomoles per litre) with positive adrenal antibodies. Twenty months after presentation a 250 microgram short synacthen test was repeated and was abnormal (basal cortisol 212 nanomoles per litre, 60 min cortisol 340 nanomoles per litre), adrenal antibodies remained positive and 8am ACTH was 93 (normal range 5 to 36). She was commenced on 5 milligrams three times a day of hydrocortisone, and after a month had gained one kilogram in weight and reduced frequency and severity of hypoglycaemia and postural hypotension, although her glycaemic control remained variable.
This case highlights the high index of suspicion required to exclude hypoadrenalism in with patients with unstable type 1 diabetes and other autoimmune endocrine disease. The presence of adrenal antibodies should prompt the possibility of Addisons disease in evolution, which would not be excluded by a one off normal synacthen test result. Repeated testing for Addisons disease in these patients should continue.