<p>Cognitive decline (CD) is a common disorder in patients with type 2 diabetes mellitus (T2DM), which is affected by various factors. The present study aimed to investigate the factors affecting its occurrence CD in patients T2DM. The PubMed, Web of Science, Scopus, and Embase databases were searched for pertinent research on the risk factors for the beginning of CD. The remaining studies were assessed using predetermined inclusion and exclusion criteria after duplicate studies were eliminated. The Comprehensive Meta-Analysis software (version 2) was used to analyze the data. The Egger test and Begg and Mazumdar test was used to examine publication bias, while the I-square statistic was used to evaluate study heterogeneity. 95% confidence limits and odds ratios were used in the analysis. 40 studies were authorized for assessment and statistical analysis using the systematic review procedure. These studies' findings indicate that, using both crude and adjusted analyses, the odds ratio for the occurrence of CD in people with diabetes is higher for factors like low educational attainment, men, abnormal Hemoglobin A1c (HbA1C) levels, physical inactivity, depression, and stroke. Factors like low education, abnormal HbA1C levels, depression, and stroke as well increase the risk of developing CD in diabetic patients. These cases in diabetic patients require special attention.</p>