Tevfik Demir completed his primary education at Isparta Ülkü Primary School and his secondary and high school education at Isparta Anatolian High School. He won Akdeniz University Faculty of Medicine in 1992 and graduated in 1998. After working as a research assistant at Dokuz Eylul University Faculty of Medicine Department of Internal Diseases between 1999-2003, he passed the specialty exam and worked at Dokuz Eylul University Faculty of Medicine, Department of Internal Medicine, Department of Endocrinology and Metabolism between 2003 and 2007. After serving as a military doctor in Diyarbakır Military Hospital Internal Medicine and Endocrinology and Metabolism Diseases Polyclinic between 2007-2008, he worked in Mersin State Hospital Endocrinology and Metabolism Department between 2008-2011.
Demir, who was awarded the title of associate professor by succeeding in the associate professorship exam he took in 2011, has been working at Mersin State Hospital until the end of 2011. He has been working as a lecturer at Dokuz Eylül University Faculty of Medicine since 2011. Between 2012 and 2013, he served as the Head of the Department of Endocrinology and Metabolism Diseases, Department of Internal Medicine, Department of Internal Medicine, Faculty of Medicine, Dokuz Eylul University. Since 2017, he has been working as a professor at Dokuz Eylul University Faculty of Medicine, Department of Internal Medicine, Department of Internal Medicine, Endocrinology, and Metabolic Diseases.