Introduction: Multiple studies have shown the relationship between heart failure (HF) and development ofdepression. Several studies have demonstrated worse perception of quality of life among patients with type 2diabetes mellitus (T2DM). We aimed to assess the association between glycated hemoglobin (HbA1c) levelsand depression severity in patients with diabetic HF.Patients and Methods: Between July 2015 and June 2016, 179 patients with HF (left ventricular ejectionfraction < 35%) and T2DM were included in the study. Blood samples for HbA1c were obtained from patientswith T2DM. The severity of depression was assessed using the Beck Depression Inventory (BDI). Patientswith depression were classified as follows: minimal with score 0-13 (group I), mild with score 14-19 (groupII), moderate with score 20-28 (group III), and severe with score 29-63 (group IV).Results: The median age of the study population was 64 (57-75) years (98 females and 81 males). There wasno significant difference between the groups regarding the frequency of hypertension and gender. There wasa significant positive correlation between BDI and HbA1c levels in patients with HF (r= 0.488, p< 0.001).According to the analysis performed between the groups, HbA1c values were found to be significantly higher ingroup IV than in groups I, II, and III (6.0 ± 1.47, 6.4 ± 0.6, 7.03 ± 0.7, and 7.6 ± 1.23, respectively; p< 0.001),which indicate the association between severity of depression and HbA1c level.Conclusion: We detected a significant association between BDI and HbA1c level in patients with chronic HFwith T2DM. Therefore, more strict control of blood glucose level may improve quality of life and decreasedepressive symptoms in patients with diabetic HF.