BACKGROUND: It is expected that a steady increase in the incidence of diabetes and resistant hypertension (RHTN), along with an increase in life expectancy, will lead to a noticeable increase in the proportion of patients with heart failure with preserved ejection fraction (HFpEF). At the same time, data on the frequency of HFpEF in a selective group of patients with RHTN in combination with diabetes are still lacking, and the pathophysiological and molecular mechanisms of its formation have not been yet studied sufficiently.AIM: To assess the features of the development HFpEF in diabetic and non-diabetic patients with RHTN, as well as to determine the factors associated with HFpEF.MATERIALS AND METHODS: In the study were included 36 patients with RHTN and type 2 diabetes mellitus (DM) (mean age 61.4 ± 6.4 years, 14 men) and 33 patients with RHTN without diabetes, matched by sex, age and level of systolic blood pressure (BP). All patients underwent baseline office and 24-hour BP measurement, echocardiography with assess diastolic function, lab tests (basal glycemia, HbA1c, creatinine, aldosterone, TNF-alpha, hsCRP, brain naturetic peptide, metalloproteinases of types 2, 9 (MMP-2, MMP-9) and tissue inhibitor of MMP type 1 (TIMP-1)). HFpEF was diagnosed according to the 2019 AHA/ESC guidelines.RESULTS: The frequency of HFpEF was significantly higher in patients with RHTN with DM than those without DM (89% and 70%, respectively, p=0.045). This difference was due to a higher frequency of such major functional criterion of HFpEF as E/e’≥15 (p=0.042), as well as a tendency towards a higher frequency of an increase in left atrial volumes (p=0.081) and an increase in BNP (p=0.110). Despite the comparable frequency of diastolic dysfunction in patients with and without diabetes (100% and 97%, respectively), disturbance of the transmitral blood flow in patients with DM were more pronounced than in those without diabetes. Deterioration of transmitral blood flow and pseudo-normalization of diastolic function in diabetic patients with RHTN have relationship not only with signs of carbohydrate metabolism disturbance, but also with level of pulse blood pressure, TNF-alfa, TIMP-1 and TIMP-1 / MMP-2 ratio, which, along with the incidence of atherosclerosis, were higher in patients with DM than in those without diabetes.CONCLUSIONS: Thus, HFpEF occurs in the majority of diabetic patients with RHTN. The frequency of HFpEF in patients with DN is significantly higher than in patients without it, which is associated with more pronounced impairments of diastolic function. The progressive development of diastolic dysfunction in patients with diabetes mellitus is associated not only with metabolic disorders, but also with increased activity of chronic subclinical inflammation, profibrotic state and high severity of vascular changes.