In this study, microscopic qualitative analysis of the oral epithelium cytological smears in the potential early phase of diabetes was performed and a comparison was made between type I and II diabetic patients and a healthy control group. The cytological assessment of the oral changes was realized on superficial and profound smears, from cheek and ventral tongue mucosa and buccal and palate. It was stained with PAP stain (Papanicolaou), and cytological changes of the oral cell population were correlated with the type, duration, and complications of diabetes. To detect changes, the experiment was conducted on 100 samples: 50 healthy people, 50 people with type I diabetes, and type II diabetes. They were taken from different areas, stained, and then examined with an optical microscope to calculate the number of cells and compare them. The results showed that the number of cells in healthy people is much higher than in people with diabetes. The increase in the cheek area and the decrease in all areas of the oral cavity. The diagnosis was made according to age groups and based on the sugar level and cumulative blood sugar. The results proved a statistical relationship between the sugar level and the number of cells in the oral cavity, considered a modern diagnostic method for diabetes.