ALTERED ADRENOCORTICOTROPIN AND CORTISOL SECRETION IN ABDOMINAL OBESITY - IMPLICATIONS FOR THE INSULIN-RESISTANCE SYNDROME

Objectives. To investigate the relationship between the pituitary-adre nocortical function, abdominal obesity, and insulin resistance syndrom e. Design. A prospective study. Setting. Helsinki University Hospital, Finland. Subjects. Sixty-six healthy males aged 30-55 years. Main out come measures. Isulin, C-peptide, cortisol and ACTH responses during t he oral glucose tolerance test (OGTT), and the cortisol response to de xamethasone suppression and intravenous adrenocorticotrophic hormone ( ACTH) stimulation. Results. The subjects in the highest tertile of the waist-to-hip ratio (WHR) had lower high-density lipoprotein cholester ol (HDLC) (P < 0.05), but higher triglyceride (TG), insulin, and C-pep tide levels, ACTH response to glucose at 2 h, and cortisol response to ACTH (P < 0.01) than those in the lowest tertile. The cortisol respon se to ACTH correlated positively, but cortisol levels during the OGTT correlated negatively with WHR. The ratio of these cortisol determinat ions correlated positively with the body-mass index (BMI) (r=0.554; P< 0.001), WHR (r= 0.536; P<0.001), TG (r=0.397; P=0.001), fasting insuli n (r = 0.534;P < 0.001) and C-peptide (r = 0.458; P < 0.001), and nega tively with HDLC (r=0.353; P=0.004). In multiple regression analyses, BMI and the 2-h ACTH response to glucose were significant predictors o f WHR and, in addition, the cortisol ratio, WHR, and BMI of insulin. C onclusions. Abdominal obesity may be associated with subtle central ad renal insufficiency, which might also affect insulin and lipoprotein m etabolism.