Joslin Diabetes Center is one of twenty-two Type 1 Diabetes TrialNet International Clinical Centers at the forefront of type 1 diabetes research. Led by Jason Gaglia, MD, MMSc, the TrialNet team at Joslin Diabetes Center is dedicated to preventing type 1 diabetes and stopping disease progression by preserving insulin production before and after diagnosis.

Our Team

Jason Gaglia, MD, MMSc

Jason Gaglia, MD, MMSc

Principal Investigator

Dr. Gaglia’s research has been focused on immunology and type 1 diabetes. His accomplishments include cloning the immune regulatory molecule TIM-3, being a member of the National Institutes of Health Clinical Islet Transplant Program, and leading a clinical trial demonstrating the feasibility of using magnetic resonance imaging to measure inflammation in the pancreas with the development of type 1 diabetes.

Maria Koen

Maria Koen, NP-C, CDE

Research NP/Sub-Investigator

Maria Koen is a Family Nurse Practitioner and Certified Diabetes Educator who has specialized in the care of patients with diabetes since 2001. Her clinical and research interest areas include management of Type 1 diabetes, advanced technologies including pump therapy and CGM systems and modalities aimed at prevention of diabetes.  In her role as a clinical research nurse practitioner, she conducts research focused on improvement in glycemic control and/or preservation of beta cell function in individuals with Type 1 diabetes. 

Christina Astley

Christina Astley, MD, ScD


Christina is a physician-scientist at Boston Children's Hospital with research interests in the drivers of type 1 diabetes remission and dysglycemia (supported by a K23 from the National Institute of Diabetes and Digestive and Kidney Diseases), as well as causal inference methods for understanding the origins of complex diseases. Her background is in pediatric endocrinology (MD from the Harvard-MIT Division of Health Sciences and Technology at Harvard Medical School, Residency and Fellowship at Boston Children's Hospital) as well as mathematical modeling and epidemiology (ScD from the Harvard School of Public Health). She is currently an Instructor in Pediatrics at Harvard Medical School, an Attending in Endocrinology at Boston Children's Hospital, and Affiliate Faculty of the Joslin Diabetes Center. 

Hannah Na

Hannah Na, BS

Clinical Research Coordinator

Hannah is one of the Clinical Research Coordinator’s on Dr. Gaglia’s immunobiology research team at the Joslin Diabetes Center. She received her Bachelor of Science degree in Computer Science with a minor in Molecular Biology from Bowdoin College in 2022. Hannah joined the TrialNet team in March of 2022, where she has been working on a variety of clinical trials studying type 1 diabetes in children and adults. Hannah was diagnosed with type 1 diabetes in 2016 and has previously worked in various diabetes research labs and as a camp counselor at the Joslin summer camp.

David Kim

David Kim, BS

Clinical Research Coordinator

David is one of the Clinical Research Coordinator’s on Dr. Gaglia’s immunobiology research team at the Joslin Diabetes Center. He graduated from Boston College in 2021 with a Bachelor of Science degree in biology. Throughout his undergraduate experience, he worked under Dr. Emrah Altindis to study the effects of Parabacteroides distasonis on the gut microbiome in hopes to define a potential link between Type 1 Diabetes pathogenesis and the gut microbiota. His interest in immunobiology continues to inspire his work with TrialNet.

Belle Lin

Belle Lin, BS

Research Assistant

Belle is the Research Assistant on Dr. Gaglia’s immunobiology research team at the Joslin Diabetes Center. She received her Bachelor of Science degree in Human Biology, Health and Science, with minors in Gerontology, Health Policy, and Infectious Disease from Cornell University in 2021.  Belle joined the TrialNet team in June 2022, and she is excited to work on clinical trials studying the prevention and intervention of type 1 diabetes in children and adults.

Research Studies

Risk Screening Risk Screening for Relatives

If you have a relative with T1D, you may be eligible for risk screening that can detect the early stages of T1D years before symptoms appear. More

Monitoring Monitoring

Depending on your risk screening results, you may be eligible for monitoring. We’ll monitor you for disease progression and let you know if you become eligible for a study. More

Prevention Study Abatacept Prevention Study

TrialNet tested the drug abatacept to see if it could delay or prevent stage 1 T1D (two or more diabetes-related autoantibodies, but normal blood sugar) from progressing to stage 2 (abnormal blood sugar) or to stage 3 (clinical diagnosis). In an earlier study in people newly diagnosed (stage 3), participants treated with abatacept had 59% better insulin production and a 9.6-month average delay in progression of insulin loss compared to those who received placebo. That difference extended out to 3 years. Details

Prevention Study Hydroxychloroquine (HCQ)

We are testing the drug hydroxychloroquine (HCQ) to see if it can delay or prevent early stage T1D (stage 1) from progressing to abnormal glucose tolerance (stage 2) and ultimately prevent clinical diagnosis (stage 3). HCQ is already used to reduce symptoms and progression of other autoimmune diseases, such as rheumatoid arthritis and lupus. This is the first study to see if it can prevent or delay T1D. Details

Long Term Long-Term Follow-up

If you are diagnosed with T1D while participating in one of our prevention studies, we’re still here for you. You can continue to receive personal monitoring while helping us learn more. More

Newly Diagnosed Tolerance Using Plasmid (TOPPLE) Study: Phase 1

TrialNet is testing the safety of a new treatment, NNC0361-0041, in adults diagnosed with type 1 diabetes (T1D) in the past 48 months. This is a Phase 1 study, which means it is the first time this treatment is being tested for safety in people. If this study results in no safety concerns, we plan to conduct a larger study to see if this same treatment can slow down or stop T1D in people at high risk, before clinical diagnosis. More