Diabetes mellitus is associated with increased risk of dementia, especially in patients with mild cognitive impairment, including changes which are unlikely to be found in everyday clinical practice, especially in patients with diabetes, which is associated with the presence of disease complications. Therefore, you must understand the importance of screening for cognitive disorders in the early stages in patients with diabetes mellitus. The aim of our study was to investigate the feasibility of the Stroop test to determine the state of cognitive impairment and cerebral blood flow status in the relevant areas of the brain evidenced by single-photon emission computed tomography (SPECT). The study involved 40 patients aged 60 to 70 years. The 27 women and 13 men. Exclusion criteria were the presence of stroke, traumatic brain injury, the abuse of alcohol. Evaluation of cognitive impairment was carried out using the Stroop test. For information on the perfusion of brain tissue using single photon emission computed tomography (SPECT). Patients were divided into 2 groups. The first group included patients who by SPECT were found hypofrontality, the second-with no signs of it. There has been a significant decrease in executive functions during the Stroop test of the part 3 in the patients of the first group than the second group. That is, the first group of patients, there is a decrease in cerebral blood flow in the anterior cingulate cortex and dorsolateral prefrontal cortex, which is confirmed by a SPECT of hypofrontality. Stroop test, a sensitive test in patients with diabetes mellitus type 2 and can be recommended for the diagnosis of cognitive disorders and diabetes associated disorders, for early detection of abnormalities in the cognitive field that will allow for the timely prevention of the condition and reduce the disability of patients.