Sidney C. Ontai, M.D., MBA

Sidney C. Ontai, M.D., MBA

Assistant Professor, Texas A&M College of Medicine

Dr. Ontai is a full time Texas A&M clinical faculty and a director of DeTar Healthcare System's family medicine residency program. He has been in practice for 30 years, in private rural practice for a community clinic and as faculty in three previous family practice residencies at the University of California - Irvine, University of Southern California and Texas Tech University.

A graduate of Harvard University, Dr. Ontai received his medical degree from the University of Hawaii Medical School, and obtained an MBA from the University of California –Los Angeles. He is certified by the American Board of Family Medicine.

Dr. Ontai has a special interest in reversing and preventing diabetes, coronary artery disease and other chronic illnesses with whole plant based diets and water only fasting. He also uses telemedicine to see patients in rural West Texas communities and to expose residents to this important clinical tool.


Mark L. Stevens, M.D.

Mark L. Stevens, M.D.

Assistant Professor, Texas A&M College of Medicine

Dr. Stevens brings 25 years of family medicine experience, including time spent in private practice, to the residency clinic.

Dr. Stevens received his medical degree from the University of Texas Medical School in San Antonio, and completed his residency at San Jacinto Methodist Hospital in Baytown. He worked as Clinical Preceptor for the University of Texas Medical Branch School of Medicine where he was named UTMB’s Preceptor of the Year. He is certified by the American Board of Family Medicine.

Dr. Stevens is a Victoria native, having been born at DeTar Hospital, and he is dedicated to the health and well-being of the people of this area. He is particularly interested in diabetes prevention and management.