Introduction: Diabetes mellitus is a chronic metabolic disorder that induces elevated plasma glucose levels. Diabetic patients are more susceptible to infections, especially fungal infections. There is a direct relationship between increased blood glucose levels and the number of Candida hyphae in the oral mucosa. This study aimed to evaluate oral candidiasis and the different Candida species found in patients with and without diabetes mellitus. Methods: A search for studies on oral candidiasis and diabetes mellitus was carried out in the following databases: PubMed (MEDLINE, Cochrane Library), Web of Science (WoS) and Google Scholar. For dichotomous outcomes, the estimates of effects of an intervention were expressed as odds ratios (OR) using the Mantel-Haenszel (M-H) method with 95% confidence intervals. Results: 25 studies were included in this meta-analysis. Diabetes Mellitus patients tripled the probability of being infected by Candida species (OR:3.16, p<0.001). Likewise, Candida species infections were more likely in patients with poor glycemic control (OR:2.94, p<0.001) and with dentures (OR:2.22, p<0.001). In contrast, neither gender nor diabetes mellitus type of diabetes conditioned fungal infections (p>0.05). The most prevalent Candida species in both diabetics and controls were C. albicans and C. tropicalis. Diabetics had significantly fewer C. non-albicans species oral infections than non-diabetics (p=0.04). Conclusions: Diabetics are more prone to oral candidiasis, especially C. albicans infections.