Mary & Dick Allen Diabetes Center
Ranked #33 Nationally in Diabetes & Endocrinology
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- Diabetes 101
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- Meet the Team
- Contact Us
Hoag is committed to improving lives for people with diabetes through clinical and educational services. The Mary & Dick Allen Diabetes Center delivers innovative, personalized programs for patients of all ages and all types of diabetes diagnosis.
Quick support
What is your risk of developing type 2 diabetes?
Take our online health risk assessment to discover if you are at risk of developing type 2 diabetes. After taking this assessment you’ll get more information on what your next steps should be.
Virtual Events and Cooking Classes
Register for cooking demonstrations and community education classes to learn and be empowered to thrive with diabetes. Cooking classes include healthy recipes designed by nutritionists to help you manage your diabetes.
Join a Support Group
Hoag hosts support groups for people with Type 1 Diabetes, Type 2 Diabetes and diabetes during pregnancy.
We believe every child and adult with diabetes deserves advanced, comprehensive and compassionate care.
The Mary & Dick Allen Diabetes Center provides a full range of services for both adults and children with diabetes. Our team includes endocrinologists, certified diabetes care & education specialists (CDCES), registered dietitians (RD), registered nurses (RN), a nurse research coordinator and a national board certified health & wellness coach. Clinical, educational and support services offered here at Hoag are designed to meet the needs of patients with diabetes and their families. Specialty programs include:
Medical nutrition therapy
ADA-accredited diabetes self-management education
The Mary & Lee Iacocca Program in Type 1 Diabetes
Herbert Program for Young Adults with Type 1 Diabetes
Type 2 Diabetes Support
Ueberroth Family Program for Women with Diabetes
Sweet Success Program for Pregnant Women
Hoag Hospital is Recognized for High Performance for Diabetes Care
Pre-diabetes
Type 1 Diabetes (T1D)
Type 2 Diabetes
Pregnancy & Diabetes
Patient Testimonial Carousel
“Dr. Ahn is amazing. He puts a lot of emphasis on the social aspect of diabetes. He takes a more holistic approach to his care. To him, it is not just about treating the disease part of diabetes, but also the psychosocial dynamics of the disease.”
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Contact usDiabetes 101
In simple terms, diabetes refers to a condition that develops when the body is unable to process the glucose (sugar) from food effectively subsequently resulting in above normal (high) levels of sugar in the blood. If left unmanaged, persistent high blood sugar levels can have serious health consequences leading to heart disease, significant nerve damage, poor blood circulation in the feet, vision (eye) -related complications, and kidney disease.
In people without diabetes, a hormone called insulin (secreted by an organ called pancreas) works efficiently to transport the glucose from the food to body cells to be used as energy for the body. In people with diabetes however, this mechanism gets disrupted and the body is unable to use the glucose effectively as a result of a complete lack of or less than adequate levels of insulin. This causes glucose (sugar) to build up in the blood stream leading to high blood glucose.
Common diabetes symptoms include:
Increased thirst and urination
Increased hunger
Fatigue
Blurred vision
Numbness or tingling in the feet or hands
Sores that do not heal
Unexplained weight loss
These symptoms can start quickly, in a matter of weeks or develop slowly—over the course of several years. Often these symptoms can be so mild that they go unnoticed by patients.
Types of Diabetes
In type 1 diabetes the body attacks and destroys insulin-producing cells; as a result, no insulin is produced. We still do not fully understand why this happens although based on current research and scientific evidence we know that it is not related to our diet or lifestyle. About 5-10% of all people with diabetes have type 1 diabetes. Until there’s a cure, this type of diabetes requires lifelong insulin therapy and glucose monitoring.
Type 2 diabetes is the most common form of diabetes. In people with type 2 diabetes, either the body does not produce adequate levels of insulin, or it is unable to use the insulin being produced effectively (also known as insulin resistance). As a result, the glucose starts building up in the blood stream leading to high blood glucose. We now know that a variety of genetic and environmental (lifestyle) factors together increase our risk for type 2 diabetes. This form of diabetes was typically seen in people above the age of 40, however, in the last decade or so an increasing number of children are developing type 2 diabetes.
Gestational diabetes is a form of diabetes that can develop during pregnancy. It is a result of the body not being able to produce enough insulin to cope with the additional bodily changes and demands that normally occur during pregnancy. Women are usually diagnosed in the late second-early third trimester of their pregnancy. However, a few women may get diagnosed early on in their pregnancy and it could be that they had underlying diabetes or insulin resistance before they became pregnant – but weren’t aware of it.
All women with gestational diabetes have an increased risk of developing type 2 diabetes later in life and are encouraged to get tested for diabetes or prediabetes every 3 to 5 years.
Before people develop type 2 diabetes, they may have a condition called “prediabetes”, which means their blood glucose levels are higher than normal but not high enough yet to be diagnosed as diabetes. Long-term damage to the body, especially the heart and circulatory system, may be occurring during prediabetes. People with prediabetes you should be checked for type 2 diabetes every one to two years.
Diabetes Management
When you have diabetes, the goal is to maintain blood glucose at a healthy level to prevent future complications and keep your diabetes in control. A diabetes care team can work with you to create a diabetes treatment plan that includes:
Medical nutrition therapy (MNT)- whether you have type 1, type 2, or gestational diabetes, it is not only important to be aware of what you eat but, also how much and when you eat.
Physical activity – daily exercise is one of the most important parts of maintaining your blood glucose levels. It is recommended to partake in 30 minutes of moderate exercise every day to avoid the risk of future complications.
Medication – for type 2 diabetes, you may need to take pills, injectable medication, and/or insulin. To control type 1 diabetes, insulin must be taken through injections or an insulin pump.
Monitoring – it is necessary to frequently monitor yourself to see how your diabetes treatment plan is working to meet your target blood glucose goals
At the Mary & Dick Allen Diabetes Center, we believe that every patient with diabetes is unique and should be provided with treatment options that are best suited to their lifestyle. We offer our patients a multidisciplinary team approach to diabetes management. Our services include physician consultations, culturally competent education, highly trained certified diabetes educators, and psycho-social care including peer support groups. We work together to achieve best possible clinical and psychological outcomes for our patients.
For more information, please visit the American Diabetes Association.
The Mary & Dick Allen Diabetes Center is dedicated to making a positive difference in the lives of people with diabetes through its clinical, education and support services. Innovative and customized programs at the Allen Diabetes Center include the Sweet Success Program tailored for women who have diabetes while pregnant; pediatric diabetes services, and the Herbert Program for Young Adults with Type I Diabetes.
Diabetes Statistics
- In 2018, 34.2 million children and adults – or 10.5% of the US population – have diabetes.
- Another 88 million Americans have prediabetes and are at risk for developing type 2 diabetes.
- Recent estimates project that as many as one in three American adults will have diabetes in 2050 unless we take steps to Stop Diabetes.
- People with diabetes are nearly twice as likely to be hospitalized for a heart attack or stroke.
- Diabetes causes 50% of all cases of kidney failure.
- More than half a million American adults have advanced diabetic retinopathy, greatly increasing their risk for severe vision loss.
- More than half of all amputations in adults occur in people with diabetes.
- About 60-70 percent of people with diabetes have mild to severe forms of nerve damage that could result in pain in the feet or hands, slowed digestion, sexual dysfunction and other nerve problems.
- The American Diabetes Association estimates that the total national cost of diagnosed diabetes in the United States is $327 billion.
- Direct medical costs reach $237 billion and the average medical expenditure among people with diabetes is 2.3 times higher than those without the disease.
- Indirect costs amount to $90 billion (disability, work loss, premature mortality).
- One in 7 health care dollars is spent treating diabetes and its complications.
- One in 4 health care dollars is spent caring for people with diabetes.
Services
Our services are comprised of assisting teens and young adults transition to adult care, offering individualized and culturally sensitive education for adults with or at-risk for diabetes, and to provide education and support for women who are pregnant with diabetes or plan to become pregnant. Our programs and services are designed to overcome cultural, socioeconomic, and linguistic barriers with a strong focus on psychosocial support as part of the patient’s experience with us.
About Us
History & Mission
The Mary & Dick Allen Diabetes Center at Hoag, founded in 2009 after the Allens’ granddaughter was diagnosed with type 1 diabetes, is dedicated to empowering and supporting people with diabetes or at risk through patient-centered care, education, prevention, and community advocacy, with a strong focus on overcoming barriers and providing psychosocial support.
Community Outreach
Discover how the Allen Diabetes Center goes beyond clinical care—offering free cooking demos, prevention programs, senior education, and peer support groups that bring practical tools and community connection to life with diabetes.
Intern Opportunities
Step into a hands-on learning experience at the Allen Diabetes Center—where interns and dietetic preceptors contribute to real research, develop culturally sensitive programs, shadow experts, and make a direct impact in the lives of people living with diabetes.
Patient Stories
Living with diabetes can be challenging, but it also inspires stories of resilience, hope, and transformation. Our patients and families generously share their experiences to help others feel less alone, offer encouragement, and show what’s possible with the right care and support. From learning how to manage diabetes day-to-day, to celebrating milestones in health and wellness, these stories highlight the strength of our community and the compassionate care that makes Hoag a trusted partner in every stage of the journey.
Programs
The Mary & Dick Allen Diabetes Center offers one of Orange County’s most comprehensive outpatient programs for adults, children, and families living with diabetes—providing specialized medical care, education, and support services tailored to every stage of life.
Resources & Events
Events
Diabetes Cooking
Healthy Recipes
Referral Info
Support Groups
SHAPE Program
Meet Hoag's Diabetes Team
Physicians and Leadership
David T. Ahn, MD
Dr. David Ahn is an Endocrinologist with a focus in Diabetes and Metabolism and currently serves as Chief of Diabetes Services at Hoag. He previously was an Assistant Clinical Professor at UCLA. Born and raised in Southern California, Dr. Ahn received his Medical Degree and completed a fellowship in Endocrinology at UC San Diego. He is passionate about empowering people with type 1 diabetes, type 2 diabetes, pre-diabetes and gestational diabetes to optimize their blood sugar control while minimizing the emotional burden of living with chronic disease. He has an interest in diabetes technology, including continuous glucose monitors, insulin pumps and smartphone apps.
Kris V. Iyer, M.D., F.A.C.P., F.A.C.E
Senior Vice President & Chief Physician Development Officer
Diana W. Zhao, MD
Dr. Diana Zhao is an endocrinologist who provides treatment for obesity and weight management, diabetes, as well as other endocrine disorders. After earning her medical degree at Medical College of Wisconsin, she returned to Southern California to complete an internal medicine residency at LAC + USC Medical Center, followed by a fellowship in Endocrinology at Harbor-UCLA and City of Hope Medical Center. During the COVID-19 pandemic she worked as a hospitalist and served as clinical instructor at the UCLA School of Medicine which greatly broadened her clinical experience. She sees patients with many types of endocrine disorders and has a clinical interest in obesity medicine. She values every interaction with her patients. Dr. Zhao finds it rewarding when she can educate her patients in a way that they understand. She strives to relieve her patients’ burdens of chronic metabolic diseases with both a shared decision making and an evidence-based approach. Dr. Zhao is excited to have returned to her hometown of Irvine to serve Orange County residents. Having grown up in China, Dr. Zhao is fluent in Mandarin. During her free time, she enjoys yoga, traveling and spending time with her husband and son.
Karen Engelman
Director, Diabetes Center
Christine Miller
Front Office Supervisor
Jonathan K. Huang, MD
<div> <p dir="ltr" style="text-align: start;"><span>Jonathan K. Huang, MD is an endocrinologist who specializes in Type 1 Diabetes, Type 2 Diabetes, and other endocrine or metabolic disorders. Dr. Huang earned his Bachelor of Arts in Neuroscience at Pomona College in Claremont, CA, graduating magna cum laude in 2014. He obtained his Doctor of Medicine degree in 2019 at the Keck School of Medicine at the University of Southern California, where he remained for his Internal Medicine Residency in 2022 and Endocrinology Fellowship in 2024. </span></p> <p dir="ltr" style="text-align: start;"><span>Throughout his career, Dr. Huang has accumulated significant achievements and accolades. His research has been published in prestigious journals, and he has also presented his work at various conferences, such as the Society of Academic Emergency Medicine Western Regional Meeting and the American Association of Clinical Endocrinologists. His contributions to medical education include serving as the Managing Director for the Keck Peer Instruction Program. </span></p> <p dir="ltr"><span>Outside of his professional life, Dr. Huang is an avid learner and enjoys cooking, golfing, and exploring new advancements in his field that allow him to better serve his patients. His dedication to both clinical and research excellence and innovation is matched by his commitment to serving his patients and the community.</span></p> </div>
Clinical Staff
Kirsten Bohrnell, R.D., C.D.C.E.S.
Registered Dietitian Certified Diabetes Care & Education Specialist
Cristi Bristol, BSN, RN, CDCES
Certified Diabetes Care and Education Specialist Registered Nurse
Michelle Connell, RN, CDCES
Certified Diabetes Care and Education Specialist
Meghan Gonzalez, RD, CDCES
Certified Diabetes Care and Education Specialist Registered Dietitian
Ruth Hwang, P.A.-C.
Physician Assistant Endocrinology
Julia Murphy, P.A.-C.
Physician Assistant Endocrinology
David Pham, PharmD, BCPS, CDCES, BC-ADM, APh
Diabetes Pharmacist Certified Diabetes Care and Education Specialist
Michelle Speetzen, BSN, RN, CDCES
Registered Nurse Certified Diabetes Care and Education Specialist Inpatient Diabetes Educator
Elizabeth Vitale, MS, RD, CDCES
Certified Diabetes Care and Education Specialist Registered Dietitian Training in Adult Weight Management
Valerie Wolf, B.S.N., R.N., R.D., C.D.C.E.S.
Registered Nurse Registered Dietitian Certified Diabetes Care & Education Specialist Research Coordinator
Support Staff
Martha Castelan
Medical Assistant
Itzel Garcia Vasquez
Medical Assistant
Violet Marquez
Medical Assistant
Diabetes Research & Wellness Coordinators
Brittany Dennis, M.S.
Research Coordinator
David Mina, M.P.H., C.D.C.E.S.
Health & Wellness Program Coordinator Certified Diabetes Care and Education Specialist
Valerie Wolf, B.S.N., R.N., R.D., C.D.C.E.S.
Registered Nurse Registered Dietitian Certified Diabetes Care & Education Specialist Research Coordinator
Contact the Mary & Dick Allen Diabetes Center
The Mary & Dick Allen Diabetes Center is located at Hoag Health Center - Newport Beach and Hoag Health Center - Irvine (Woodbridge). These facilities have classrooms with state of the art education technology and private consultation rooms for individual patient appointments.
Phone: 949-764-8065 Email: DiabetesCare@hoag.org
The Allen Diabetes Center offers a variety of programs and services to help manage your diabetes, such as:
Diabetes Education and Medical Nutrition Therapy (MNT)
Advanced Diabetes Education
Weight Management / Diabetes Prevention
Gestational Diabetes (Sweet Success)
Registered Dietitian Consultation
Endocrinology Consultation
Please have your physician complete the referral form to be eligible to participate in the above services.