Question 246

Question:

A 25-year-old woman with previously well controlled type 1 diabetes mellitus develops ketoacidosis 2 days after onset of a urinary tract infection. The most likely cause of the ketoacidosis is decreased efficacy of insulin on muscle, adipose tissue, and liver resulting from antagonism by which of the following hormones?

Correct Answer: B.  Cortisol

Acute physical or psychological stress activates the hypothalamic-pituitary-adrenal axis, resulting in increased plasma ACTH and (B) cortisol concentrations. Fever, caused by systemic infection or by pyrogen administration, is a potent stimulus of ACTH and cortisol secretion, while infection causes release of interleukins IL-1 and IL-6, which stimulate hypothalamic CRH secretion, and tumor necrosis factor-alpha, which stimulates ACTH secretion directly.

Cortisol, in turn, acts as a physiological antagonist to insulin by inhibiting glycogenesis, promoting lipolysis, and mobilizing extrahepatic amino acids and ketone bodies. This leads to gluconeogenesis with resultant increased circulating glucose concentrations.