Overnight low-dose dexamethasone suppression test in depressed patients with or without diabetes:a clinical control study

Abstract

Objective To explore the possible role of hypothalamic-pituitary-adrenal axis(HPA) dysfunction in mechanism of diabetes in depressive patients.Methods Two groups including depressed patients with newly diagnosed diabetes(case group,n=40),depressed patients with normal glucose homeostasis(control group,n=40)were included,and undertook overnight low-dose dexamethasone (1 mg)suppression test(LDDST)and fasting plasma glucose,2 h plasma glucose after 75 g glucose loading measurement before medication.Results The plasma cortisol levels in case group at baseline time point of 8:00 and 16:00,and 8:00 after 1 mg dexamethasone were significantly higher than that in control group[(608±266)nmol/L VS.(499±199)nmol/L;(409±176)nmol/L vs.(299±148)nmol/L;(382±257)nmol/L VS.(232±182)nmol/L;P=0.042,0.003,0.004 respectively ].The escaped suppression rates in LDDST were significantly more in case group than control group(72%vs.42%,P=0.007).Plasma cortisol levels at 8:00 before and after dexamethasone were positively correlated with fasting plasma glucose in case group(r=0.392,0.470;both P<0.05).Conclusion Depressed patients with diabetes have much severe dysfunction of the HPA axis which may play an important role in the pathomechanism of diabetes in depression. Key words: Depression; Diabetes mellitus; Hydrocortisone; Dexamethasone suppression test