INTRODUCTION: Increases in fasting plasma cortisol level in the morning has been associated with glucose intolerance and insulin resistance in patients with metabolic syndrome. This study investigated the relationship between fasting morning cortisol and insulin resistance defined by homeostasis model assessment for insulin resistance (HOMA-IR) in obese women with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT).
METHODS: The study was carried out in the Obesity outpatient clinic between June and September 2005. Total body fat mass, lean body mass, total body fluid, and basal metabolic rate were calculated via bioelectrical impedance analysis. Body mass index (BMI), fasting plasma glucose, insulin, HOMA-IR, basal cortisol, 24-h urinary free cortisol, overnight dexamethasone suppression test, lipids, oral glucose tolerance test results, and thyroid function tests were obtained from patient files in the obesity clinic.
RESULTS: This study included 38 obese women, 21 (55.3%) of which had NGT. There was no significant difference between NGT and IGT cases in terms of age, BMI, waist circumference, insulin, HOMA-IR, basal cortisol, and 24-h urinary free cortisol (p=0.484, p=0.399, p=0.517, p=0.639, p=0.973, p=0.758, p=0.161, respectively). There was no correlation between basal cortisol levels in patients with NGT, however, there was a moderate correlation between basal cortisol and HOMA-IR in patients with IGT (p=0.464, r=0.629 and p=0.007).
DISCUSSION AND CONCLUSION: Although the basal cortisol levels of NGT and IGT patients were similar, a moderate correlation exists between basal cortisol and HOMA-IR in patients with IGT.