SUN-313 Depression, Subjective Stress and Serum Osteocalcin Concentrations in People with Type 2 Diabetes Mellitus

Serum osteocalcin is emerging as a potential marker of glucose homeostasis and risk of type 2 diabetes mellitus (T2DM). In mice, osteocalcin knockouts exhibit depressive-like behaviours but knockouts of a putative osteocalcin receptor, GPR158, are resistant to chronic unpredictable mild stress. Recently, osteocalcin release from bone has been suggested to mediate some aspects of the acute stress response. Here, we assess relationships between serum osteocalcin, depression and perceived stress in people with T2DM. Participants with T2DM were assessed for whether they met the DSM-5 criteria for Major Depressive Disorder using the research version of the Structured Clinical Interview for DSM-5 depression criteria (SCID-5RV). Subjective stress was assessed using the Perceived Stress Scale (PSS) with higher scores indicating greater subjective stress. Serum carboxylated (cOCN) and uncarboxylated (unOCN) osteocalcin were assayed from fasting morning blood by commercial ELISA. Among 87 participants (mean age 62.9±9.5, 52% women), 18 (26%) were experiencing a depressive episode (7 men, 11 women). Both serum unOCN and cOCN were associated with higher PSS scores in participants with depression (unOCN, r=0.566, p=0.014; cOCN, r=0.564, p=0.015) but not in those without depression (unOCN, r=0.002, p=0.985; cOCN, r=0.090, p=0.463). A significant interaction was found between depression and PSS scores predicting serum unOCN in a linear model adjusted for age, sex, body mass index, antidepressant use and HbA1c (F=6.225, p=0.015). The results are consistent with reports that osteocalcin release from bone may be a mediator of stress perception; however, among people with T2DM, this relationship was observed only among those currently experiencing a depressive episode.