Abstract Objective: To evaluate whether type 2 diabetes mellitus (T2DM) cynomolgus monkeys exhibit anxiety and depression-like behaviors, and on the basis of this analysis, to investigate the correlation between biochemical indicators and anxiety-depressive like behaviors. Methods: Three cynomolgus monkeys with fasting plasma glucose (FPG) ≥ 5.6 mmol/L were selected and included in T2DM group and three cynomolgus monkeys with FPG < 4.2 mmol/L were included in normal group. Age, sex, weight, BMI, FPG, blood lipids, atherosclerosis index (AI), and TNF-α levels were measured in each group; the human intrude test (HIT) was used to assess the anxiety-like behaviors, and apathy feeding test (AFT) were used to evaluate the depression-like behaviors of cynomolgus monkeys. Pearson's analysis was used to correlate the anxiety and depression-like behaviors with blood biochemical indexes and inflammatory factor levels. Results: (1) The levels of FPG, AI, and TNF-α in the T2DM group were higher than those in the normal group (all P<0.05), and the levels of high-density lipoprotein cholesterol (HDL-C) in the T2DM group was lower than those in the normal group (P<0.05). (2) In the HIT, the behavioral durations of the T2DM group were higher than those of the normal group in anxiety behavior (stare phase) and back of cage (stare phase) (P<0.05); and the behavioral durations of the T2DM group were significantly shorter than those of the normal group in locomotion behavior (baseline phase, profile phase, back phase) (P<0.05). (3) In the AFT, the T2DM group had a significantly higher food pick-up time than the normal group (P<0.05). (4) Pearson correlation analysis showed that in the HIT, the duration of back of cage (stare phase) was positively correlated with the AI level (r=0.828, P=0.042); and the duration of locomotion (back phase) was negatively correlated with the AI level (r=-0.842, P=0.035). Conclusion: Anxiety and depression-like behaviours were present in T2DM cynomolgus monkeys, and AI was closely associated with anxiety-like behaviors, providing new evidence for the study of the mechanism of the association between T2DM and anxiety and depression behaviors.