As the duration of diabetes mellitus (DM) increases, the risk of complications increases and the prevalence of depression becomes higher. Most studies on depression in Korean patients with DM have focused on a point 5-10 years after diagnosis, and there has not been much data reported regarding the early stages of DM, including newly developed DM. In this study, we examined whether blood glucose levels could be associated with emotional symptoms such as depression (DS) and anxiety (AS) in patients newly diagnosed with DM. Serum glucose and HbA1c were measured in 89 patients with DM. The Impact of Event Scale (IES) was used to investigate the extent of the psychological impact of a diagnosis of DM. The IES comprises four elements: hyperarousal, intrusiveness, avoidance, and sleep problems. DS and AS were investigated using the Hospital Anxiety and Depression Scales. DS was observed in 32 patients (36%) and AS was observed in 21 patients (23.6%), indicating a higher prevalence of DS and AS than in the general population. There was an inverse correlation between HbA1c and DS (Pearson`s correlation coefficient: R = -0.227; P = 0.035), but no correlation was found for AS. The four elements of the IES had significant correlations with DS and AS. Logistic regression analysis showed that sleep problems (OR = 1.437) and HbA1c (OR = 0.51) were associated with DS, but only intrusiveness (OR = 0.629) showed a correlation with AS. In patients newly diagnosed with DM, DS is associated with sleep problems and low HbA1c levels. Emotional symptoms should be considered as part of glucose control, and efforts to mitigate psychological stress during the initial period of diabetes management should be made.