Background Peripartum depression (PPD) and gestational diabetes mellitus (GDM) are pregnancy- related disorders associated with various negative consequences for both mother and child. Considering the relatively high prevalence of PPD and GDM, exploring factors associated with PPD in women with and without GDM has important clinical implications. However, such studies are scarce, limited, and inconclusive. Aims and Objectives This study aimed to explore: 1) the prevalence of depression symptoms and 2) psychosocial and anthropometric factors associated with depression symptoms in pregnant women with and without GDM. Methods The current sample of the ongoing study includes 180 women (73 with GDM, 107 with normal glucose tolerance (NGT)) recruited at the University Hospital Centre Zagreb, 1-3 days before their planned caesarean section. Participants fulfilled questionnaires: Edinburgh Postnatal Depression Scale, Depression, Anxiety and Stress Scales, Social Readjustment Rating Scale, Coping Orientation to Problems Experienced, Social Support Appraisals Scale, Perceived Support from Partner Scale, and General Data Questionnaire. Anthropometric, obstetric and clinical data were collected from medical records. Results The prevalence of depression symptoms was similar in the GDM (11%) and NGT (14%) groups and comparable to the prevalence found in previous studies in the general perinatal population. In both groups, factors that correlated with depression symptoms were: higher avoidance-oriented coping, stressful events in the first and third trimester, anxiety, stress, and lower support from friends. In the NGT group, additional correlates of depression symptoms were lower partner support, unemployment and rural residence. However, in the GDM group, additional correlates of depression symptoms were higher pre-gestational body mass index, stressful events in the second trimester, maternal smoking, lower problem-oriented coping and lower family support. Conclusions These preliminary results indicate different factors associated with depression symptoms in women with and without GDM and support a more individualized clinical approach to PPD.