Autophagy is considered as a mechanism of progression of heart failure, but under certain conditions, it can also act as an adaptation mechanism. Beclin-1 plays the key role in autophagy. We studied the features of Beclin-1 expression in cardiomyocytes of the left ventricle in arterial hypertension, type 1 diabetes mellitus, and their combination. The experiment was performed on male 38-week-old Wistar Kyoto rats and SHR rats aged 38 and 57 weeks. Type 1 diabetes mellitus was modeled by a single parenteral administration of streptozotocin. Expression of Beclin-1 in cardiomyocytes of the left ventricle was evaluated by immunohistochemical analysis. In arterial hypertension, a decrease in the intensity of Beclin-1-dependent autophagy of cardiomyocytes was seen, while in combined pathology, we observed an opposite effect manifested as a significant increase in the expression of protein Beclin-1. © 2021, Springer Science+Business Media, LLC, part of Springer Nature.