Joslin Diabetes Center is one of twenty-five 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. 

Mikayla Mackey

Mikayla Mackey, BA

Clinical Trials Manager

Mikayla is the Clinical Trials Manager for the Gaglia research group at the Joslin Diabetes Center.  She received her Bachelor of Arts degree in psychology, with a concentration in health and counseling, from Emmanuel College in 2017.  Mikayla joined the TrialNet team as a Clinical Research Coordinator in May of 2019 and recently transitioned to Clinical Trials Manager.  In this role, she helps oversee a portfolio of clinical studies examining ways to prevent and/or mitigate type 1 diabetes in children and adults. Mikayla enjoys working with the broad spectrum of TrialNet participants not only at the Joslin Diabetes Center, but also at the Joslin summer camps, and outreach events such as JDRF’s TypeOneNation.

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 is testing the drug abatacept to see if it can delay or prevent progression of early stage T1D (stage 1 or stage 2), and ultimately prevent clinical diagnosis (stage 3). In earlier studies for people newly diagnosed (stage 3), abatacept helped slow down disease progression. 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