Presentations of pituitary insufficiency and Addison's disease in insulin dependent diabetes may be similarBMJ 1996; 313 doi: https://doi.org/10.1136/bmj.313.7061.885 (Published 05 October 1996) Cite this as: BMJ 1996;313:885
- Kevin Hardy, Consultant physician,
- John Scarpello, Consultant physician
EDITOR,—We agree with Lynne Armstrong and Patrick M Bell that a high degree of suspicion is required to diagnose Addison's disease1; we too have encountered falling insulin requirements and recurrent severe hypoglycaemia as a presentation of Addison's disease in insulin dependent diabetes.2 Addison's disease is not, however, the only cause of glucocorticoid deficiency: pituitary insufficiency may present as falling insulin requirements and recurrent hypoglycaemia in insulin dependent diabetes.2 Unlike in Addison's disease, however, glucocorticoid deficiency in pituitary insufficiency does not present with pigmentation, the electrolyte disturbances of hyponatraemia and hyperkalaemia, and mild uraemia. Moreover, hypoglycaemia in pituitary insufficiency may be more severe than that in Addison's disease because of coexistent deficiency of growth hormone, another potent counterregulatory hormone.
If glucocorticoid deficiency is not to be missed, clinicians must have a low threshold for performing a short tetracosactrin test in patients with insulin dependent diabetes who have falling insulin requirements; a 30 minute serum cortisol concentration of <550 nmol/l suggests glucocorticoid deficiency and the need for steroid replacement and further investigation.