Serum melatonin levels in type 2 diabetic patients with depressive symptoms compared to non-depressed individuals

Melatonin, mainly regulating the body's circadian rhythm, may have protective effects against type 2 diabetes mellitus (DM2)-induced depression due to its antioxidant and regulatory impact in the pathogenesis of both DM2 and depression. This study aimed to find the association of serum melatonin levels with depression in DM2 patients.

A total of 50 DM2 patients were recruited in this retrospective cross-sectional study and divided into 25 patients with depression (DM2-DP) and 25 without depression symptoms (DM2-NDP). Depression was diagnosed using the Hospital Anxiety and Depression Scale (HADS) assessment. Fasting blood samples were collected and examined for the level of serum melatonin and other biomarkers. All statistical analysis was performed by SPSS software Version 22, and a p-value less than 0.05 was considered statistically significant for all tests.

The depression score was significantly lower in DM2-NDP than DM2-DP (p< 0.001). The mean weight was significantly lower in the DM2-DP group (P= 0.021). Total cholesterol, triglyceride, and anxiety scores were higher, and the melatonin level was lower in DM2-DP. The correlation of melatonin levels was positive with age, DBP, HbA1C, FBS, and TG. In contrast, it was negative with male gender, BMI, diabetes duration, SBP, TC, family history of DM, depression score, and anxiety score. However, no significant differences were seen.

Lower melatonin may be associated with depression and anxiety in patients with DM2. The serum melatonin level might be a strong predictor of depression in DM2 patients.