Decreased cortisol production in male type 1 diabetic patients

BACKGROUND: It is unclear whether cortisol production and the 11betaHSD-mediated cortisol to cortisone interconversion are different between type 1 diabetic patients and healthy subjects. MATERIALS AND METHODS: Fourteen male, nonobese, normotensive type 1 diabetic patients without severe complications (HbA1c < 8.5%) were studied twice during a daily sodium intake of 50 and 200 mmol, and were then compared with 14 individually matched healthy subjects. Cortisol production was assessed by the sum of urinary cortisol metabolite excretion. Urinary ratios of (tetrahydrocortisol + allo-tetrahydrocortisol)/tetrahydro-cortisone [(THF + allo-THF)/THE] and of free cortisol/free cortisone [UFF/UFE] were determined as parameters of 11betaHSD activity. RESULTS: Sum of urinary cortisol metabolite excretion during low- and high-salt diet was 7.4 +/- 2.5 vs. 7.7 +/- 2.3 nmol min-1 m-2 (NS) in diabetic patients and 9.7 +/- 2.1 vs. 11.2 +/- 4.1 nmol min-1 m-2 (NS) in healthy subjects, respectively (P < 0.05 vs. healthy subjects at both diets). The allo-THF excretion and allo-THF/THF ratios were lower in the diabetic than in the healthy males during both diets (P < 0.05). Urinary (THF + alloTHF)/THE and UFF/UFE were similar in both groups and remained unchanged after salt loading. CONCLUSIONS: The sum of urinary cortisol metabolite excretion as a measure of cortisol production is lower in nonobese, normotensive type 1 diabetic males with adequate glycaemic control and without severe complications, irrespective of sodium intake. We suggest that this is at least in part as result of diminished 5alpha reductase activity, resulting in a decreased cortisol metabolic clearance. In type 1 diabetic and in healthy males, the 11betaHSD setpoint is not affected by physiological variations in sodium intake.