To explore the association of nocturnal serum cortisol levels with diabetic microvascular complications in overweight or obese patients with type 2 diabetes mellitus.

Serum cortisol levels of 316 overweight or obese type 2 diabetic patients were tested at midnight by the method of chemiluminescence. Diabetic microvascular complications were compared among various groups according to nocturnal serum cortisol levels. All the patients with nocturnal serum cortisol level >50 nmol/L were asked to undergo overnight low-dose dexamethasone suppression test to rule out the possibility of subclincal Cushing′s syndrome. The incidences of diabetic nephropathy (DN), diabetic retinopathy (DR), and diabetic peripheral neuropathy (DPN) were examined in all the patients.

(1)The incidence of DN was gradually increased from 13.3% to 27.7% and 44.2% in patients with low, medium, and high cortisol level groups, showing a statistical difference among 3 groups(P<0.05). The incidences of DR in medium and high cortisol level groups were higher than that in low cortisol level group (40.6% and 47.7% vs 22.7%, both P<0.01). The incidence of DPN in high cortisol level group was higher as compared with low cortisol level group (60.5% vs 38.7%, P<0.01). (2)Nocturnal serum cortisol level in patients with diabetic microvascular complications was higher than that in patients without complications [ (136.87±105.78 vs 97.55±93.48) nmol/L, P<0.01]. Nocturnal serum cortisol level in patients with multiple diabetic microvascular complications was higher than that in patients with single diabetic microvascular complication [ (151.66±114.54 vs 117.69±90.26) nmol/L, P<0.05]. (3)Single factor logistic regression analysis showed that higher nocturnal serum cortisol level was a risk factor for diabetic microvascular complications in addition to female, age, longer diabetic duration, higher fasting plasma glucose (FPG). Multivariate logistic regression analysis showed that higher nocturnal serum cortisol level was still a risk factor for diabetic microvascular complications after adjusted by diabetic duration, FPG, HbA_1C, and the use of insulin (P=0.013).

Nocturnal serum cortisol level seems to be a risk factor for diabetic microvascular complications in overweight or obese patients with type 2 diabetes mellitus. (Chin J Endocrinol Metab, 2018, 34: 834-838)

Overweight; Obese; Diabetes mellitus, type 2; Cortisol; Diabetic microvascular complications