The ovine corticotropin-releasing hormone-stimulation test in type I diabetic patients and controls: Suggestion of mild chronic hypercortisolism

Abstract

We examined hypothalamic-pituitary-adrenal (HPA) axis function in insulin-dependent diabetic outpatients (N = 22) and age-, sex-, and weight-matched normal controls (N = 22). The evaluation included measurements of 9:00 am fasting plasma cortisol and cortisol-binding globulin (CBG) levels, 24-hour urinary free cortisol (UFC) excretion, and plasma corticotropin and cortisol responses to intravenously administered ovine corticotropin-releasing hormone ([CRH] 1 μg/kg given as a bolus at 8:00 pm). Diabetic patients had significantly elevated 9:00 am plasma cortisol levels (mean ± SE, 300.7 ± 99.3 v 237.3 ± 99.3 nmol/L, P < .04), higher 24-hour UFC excretion ( 313.2 ± 112.6 v 244.2 ± 69.3 nmol 24 h , P < .02 ), and greater cortisol responses to CRH infusion (time-integrated values: 49,408.2 ± 11,289.8 v 40,217.9 ± 7,228.6 nmol/L · 120 min, P < .004; peak cortisol values: 529.7 ± 107.6 v 438.7 ± 77.3 nmol/L, P < .002) than controls. UFC excretion values were positively correlated with both 5-year averaged hemoglobin A 1c level ( P = .03) and total number of insulin units administered per day ( P = .03). These results suggest that insulin-dependent diabetic outpatients have mild chronic hypercortisolism, which might influence the control of the disease and play a role in the development of its chronic complications.