Disturbances of the circadian rhythm of cortisol secretion are associated with depression , coronary calcification , and higher all-cause and cardiovascular mortality.The primary aim of this study was to test the associations between midnight salivary cortisol ( MSC ) , depression and HbA1c , and control for behavioural , environmental and intra individual factors with possible impact on cortisol secretion , like smoking , physical inactivity , season , medication , diabetes duration , severe hypoglycemia episodes , age and gender in patients with type 1 diabetes .