• 795 E. Second St., Ste 4, Pomona, CA 91766

  • Meet Our Team

  • Andrew S. Pumerantz, DO, FACP

    Founder, Executive Director

    An internist trained at Yale as an infectious disease specialist, Dr. Pumerantz is Professor of Internal Medicine, Assistant Provost for Strategic Initiatives, and Executive Director of the Western Diabetes Institute (WDI) at Western University of Health Sciences (WesternU). Dr. Pumerantz was formerly WesternU’s infectious disease division chief and internal medicine department chair. In 2009, he founded WDI as an academic, integrated practice and research unit focused on the 'whole person' with diabetes and multimorbidity. At WDI, Dr. Pumerantz created the Diabetes Cross- Disciplinary Index© (DXDI©) to facilitate complex phenotypic pattern and trend visualization, cross-ecosystem communication, and health outcomes tracking. In a 2015 collaboration with a clinical and technology team in the UK at the University of Dundee, a modified version of DXDI© was incorporated into NHS Scotland’s award-winning platform, “SCI-Diabetes” (Scottish Care Information-Diabetes). Dr. Pumerantz is also Visiting Clinical Professor of Global Health at Jodhpur School of Public Health, India. A 1988 graduate of Philadelphia College of Osteopathic Medicine, Dr. Pumerantz completed internal medicine residency and chief medical residency at Beth Israel Medical Center, New York. He is certified by the American Board of Internal Medicine and is a Fellow of the American College of Physicians.

  • Erene Nawar, MD


    Dr. Nawar is a clinical endocrinologist in the WDI’s Center for Endocrine and Metabolic Health where she provides valuable expertise to assist each patient in achieving and maintaining the highest level of health and wellness. Dr. Nawar works intimately with the rest of WDI’s cross-disciplinary team as well as the patient’s own primary care provider to formulate and implement a personalized and coordinated care plan. To effectively and safely optimize the control of a patient’s blood glucose levels, she and WDI’s clinical pharmacist collaborate on medication therapy management protocols, including insulin titration. In addition, Dr. Nawar’s expertise encompasses a broad range of endocrine and metabolic conditions, including obesity, osteoporosis, thyroid, parathyroid, pituitary, and adrenal disorders. She has a particular interest in polycystic ovary syndrome (PCOS) and women’s health.

    Dr. Nawar was raised in Southern California and received a Bachelor’s in Neurobiology from the University of California Irvine. She received an MD from Northwestern University’s Feinberg School of Medicine in Chicago and then returned to Southern California for internal medicine residency at the University of California Los Angeles (UCLA)-Olive View Medical Center. She joined WDI after completing fellowship training in Endocrinology, Diabetes and Metabolism at the University of California Irvine Medical Center in Orange.

  • Graciela Reza & Rosa Ybarra-Martinez

    Care Coordinator/Promotora de Salud

    The WDI care coordinators, Graciela and Rosa, are the liaisons between patients and the whole integrated healthcare team. Their passion is to ensure delivery of the best care by engaging and encouraging each patient to better problem solve and to pursue any recommended lifestyle modifications. They work directly with each patient on scheduling various follow up appointments and activities while empowering each with knowledge of their unique condition. The care coordinators provide WDI patients with links to available resources and programs within their respective neighborhoods and communities. The care coordinators strive to align the goals of the team-based care plan with each of the patient's own personal goals for their health and wellness.

  • Melanie Barbee, RDN, CDE┬«

    Registered Dietitian Nutritionist

    Melanie is a Registered Dietitian Nutritionist and Certified Diabetes Educator at WDI where she manages the ADA- and AADE-accredited programs in Diabetes Self-Management Education & Training. Mel provides personalized nutrition education and care plans in both Spanish and English and is an integral and seminal member of the WDI IPU team. A registered dietitian for over 20 years, Melanie earned a Bachelor's in Dietetics & Food Administration from California Polytechnic University, San Luis Obispo and a Master's with an emphasis in Community Nutrition from California State University at Long Beach. 

  • Christal Pham, PharmD, CDE

    Clinical Pharmacist

    As WDI's clinical pharmacist, Christal works closely with the IPU's patients who are often on multiple medications and complex regimens for several chronic health conditions in addition to diabetes. She is an indispensable provider of expertise within WDI's cross-disciplinary team to ensure the safe, cost-effective, proper, and personalized use of medications. As a Certified Diabetes Educator, Christal is an essential component of the IPU team serving as a vital resource to improve self-management education, medication adherence, and the implementation of a precise and personalized treatment plan across the full cycle of care. Christal communicates with neighborhood dispensing pharmacists as a liaison of the IPU team.

  • John Nguyen, DPT

    Physical Therapist

    Dr. John Nguyen is WDI's physical therapist in charge of the Center for Fitness and Function. He is expert in evaluating the diabetic foot as well as a patient's overall functionality and fitness. John works with the rest of the WDI team coordinating fitness and supervised exercise with nutrition and oral health to prevent disease complications by helping patients seek better lifestyles and the maintenance of optimal health. He grew up in the San Gabriel Valley and received his Doctorate of Physical Therapy (DPT) from Loma Linda University.

  • Heidi Davila, RDHAP

    Registered Dental Hygienist in Alternative Practice

    Heidi is a Registered Dental Hygienist in Alternative Practice at WDI's Center for Periodontal Health where the goal is to help people with diabetes attain and maintain their periodontal health for a lifetime. She brings twenty-five years of clinical experience working in both a general practice setting and with periodontists on specialty cases. In addition, she was a clinical instructor in the USC dental hygiene program following her graduation in 1989. Heidi's main focus at the WDI's Center for Periodontal Health is to strategically integrate periodontal and systemic health through screening of all diabetic patients for periodontitis, initiating appropriate treatment, and instructing proper oral hygiene techniques for maintenance of healthy gum tissue and teeth so as to minimize the risk of infection and to reduce systemic inflammation. Heidi refers more advanced periodontal disease cases to local dentists, as necessary, and she is an integral part of WDI's value-based "whole-person" health care delivery.

  • Edward Barnes, MD


    Dr. Barnes is a nephrologist in the Center for Kidney Health and is integral as an embedded specialist for the WDI IPU where he enjoys working closely with patients to prevent the development and progression of kidney disease. He is an expert in performing and interpreting kidney ultrasounds and he strives to incorporate technology and innovation into practice. Dr. Barnes is Associate Professor of Internal Medicine; Chief, Division of Nephrology and Hypertension; and Assistant Dean of Longitudinal & Experiential Learning at WesternU/COMP. He is also Medical Director for the DaVita Dialysis Center in south Pomona. After earning an MD from University of Kansas School of Medicine, Dr. Barnes completed internal medicine residency at Brooke Army Medical Center in San Antonio, Texas. He then served in the United States Army for a decade and is a Veteran of Operation Iraqi Freedom. During his Army service, Dr. Barnes earned the Meritorious Service Medal for exemplary work as the Dialysis Director at Brooke.

  • Cesar Ochoa, MD, PhD

    Clinical Research Coordinator

    Dr. Ochoa is the Clinical Research Coordinator and a co-investigator at the Western Diabetes Institute.

    Prior to coming to WDI, he worked at the Keck School of Medicine at USC in the Divisions of Endocrinology and Cardiovascular Medicine. Dr. Ochoa has over 10 years of experience in clinical research and education. He holds a B.S. degree in Health Sciences from the Preparatoria #2 Cuernavaca in Morelos, Mexico, a Medical Degree from University of Morelos in Mexico and completed a Postdoctoral Minority Fellowship in Research (PhD) through National Institute of Health (NIH) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) funding at the University of Southern California (USC). He was a co-investigator in landmark studies, including TRIPOD (Troglitazone in Prevention of Diabetes), PIPOD (Pioglitazone in Prevention of Diabetes), and ActNOW Multicenter Study for Diabetes Prevention. Dr. Ochoa has published peer-reviewed papers and has lectured at conferences in Mexico and USA in the fields of general research, diabetes and its prevention, obesity, metabolic syndrome, and others.

    Dr. Ochoa helps WDI coordinate its diabetes research registry (approved by the Institutional Review Board of Western University of Health Sciences). The registry allows clinical investigators to test a variety of hypotheses about population health, epidemiology, and patient-centered health outcomes. The registry supports publication of original research studies in peer-reviewed journals such as in BMJ.

  • Raymond Maeda, OD

    Clinical Director, Eye Care Institute

    Associate Dean of Clinical Affairs & Associate Professor, College of Optometry

    Dr. Maeda joins WesternU from the Indian Health Service at Hu Hu Kam Memorial Hospital in Sacaton, Arizona. Prior to that, Dr. Maeda was on faculty at the Southern California College of Optometry. His clinical interests are in primary eye care and ocular disease, particularly caring for the patient with ocular complications from diabetes. He has provided eye care for patients in a variety of settings: private practice, teaching hospital, clinical teaching facility, and inter-professional clinic. He strongly feels that his patients need to be well-informed so that they can be a partner in the treatment and care for their eyes.