Altered adrenocorticotropin and cortisol secretion in abdominal obesity: implications for the insulin resistance syndrome.

OBJECTIVE

To investigate the relationship between the pituitary-adrenocortical function, abdominal obesity, and insulin resistance syndrome.

METHODS

A prospective study.

METHODS

Helsinki University Hospital, Finland.

METHODS

Sixty-six healthy males aged 30-55 years.

METHODS

Insulin, C-peptide, cortisol and ACTH responses during the oral glucose tolerance test (OGTT), and the cortisol response to dexamethasone 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 cholesterol (HDLC) (P < 0.05), but higher triglyceride (TG), insulin, and C-peptide levels, ACTH response to glucose at 2 h, and cortisol response to ACTH (P < 0.01) than those in the lowest tertile. The cortisol response to ACTH correlated positively, but cortisol levels during the OGTT correlated negatively with WHR. The ratio of these cortisol determinations 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 insulin (r = 0.534; P < 0.001) and C-peptide (r = 0.458; P < 0.001), and negatively with HDLC (r = 0.353; P = 0.004). In multiple regression analyses, BMI and the 2-h ACTH response to glucose were significant predictors of WHR and, in addition, the cortisol ratio, WHR, and BMI of insulin.

CONCLUSIONS

Abdominal obesity may be associated with subtle central adrenal insufficiency, which might also affect insulin and lipoprotein metabolism.