There are two types of diagnostic methods: 1, identification of DNA in biological fluids by means of PCR, nested-PCR, and real-time PCR; and 2, molecular methods, such as microsatellite analysis to identify parasite strains (11). The nested-PCR assay has been reported as the most significant and sensitive assay for diagnosing toxoplasmosis (12). In a study by Fallahi et al. conducted on children with cancer to identify T. gondii infections, the nested-PCR method showed the proper sensitivity and specificity for detecting toxoplasmosis (13). Molecular diagnostics can be a very useful tool in diagnosing T. gondii in diabetic patients. In addition to finding the appropriate target gene sequences, the exact design of primers for the correct implementation of the PCR is important. Reports indicate that procedures with multiple gene copies, such as nested-PCR, are better than a single-gene copy (14). Molecular methods used in laboratories worldwide to identify the forms of T. gondii are a 529 bp repeat element (RE) (gene bank accession number AF146527), with 200 - 300 copies (15), and B1 gene (gene bank accession number AF179871) with 35 copies (14).These are used to determine sequences in the genome of T. gondii because high specificity and sensitivity are important. Accuracy and sensitivity of the two genes (RE and B1) have been compared (16-19). Finding a positive PCR in the patient’s sero-negative toxoplasmosis is an important factor, which suggests that the results may not be reliable. This is true when the nested-PCR assay with specific primers does not show false results.