The study was conducted on 93 type 1 and 93 type 2 DM patients, all recruited from the diabetic endocrine metabolic unit, Kasr El-Aini Teaching Hospital, Cairo University. Blood collected on EDTA and plain vacutainer tubes of all patients was screened for: Mitochondrial DNA mutation at position 3243, by PCR amplification followed by digestion using Apa 1 restriction endonuclease enzyme, anti-GAD ab by IRMA, anti-IA-2 ab by IRMA, anti-insulin ab by ELISA performed on type 1 DM only, All the patients were assessed for DM control by measurement of HbA1c level by quantitative colourimetric ion exchange chromatographic determination.