New research from Washington State University’s Elson S. Floyd College of Medicine provides important evidence linking blood-based biomarkers of neurodegeneration with long-term glycemic control and diabetes-related complications in adults with type 1 diabetes (T1D).
The study, led by fourth-year medical student Nikki Delgado and published in Diabetes Research and Clinical Practice, advances understanding of potential biological pathways connecting T1D with cognitive decline and risk for Alzheimer’s disease and related dementias (AD/ADRD). It included collaborators from leading research institutions across the country.
The researchers analyzed plasma samples and continuous glucose monitoring data from adults enrolled in the Glycemic Variability and Fluctuations in Cognitive Status in Adults with Type 1 Diabetes (GluCog) Study, which is led by principle investigators Naomi Chaytor, PhD, professor and chair of WSU’s Department of Community and Behavioral Health, and Laura Germine, PhD, an associate professor at the Albert Einstein College of Medicine in New York.
Investigators examined several blood-based biomarkers commonly associated with neurodegeneration and Alzheimer’s disease, including neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), amyloid beta ratios, and phosphorylated tau.
The study found that higher levels of NfL—a marker of neuronal injury—were associated with chronic hyperglycemia: higher mean glucose, lower glucose time in range, more time spent with glucose above 180 and 250 mg/dL, higher HbA1c, and the presence of diabetes-related complications such as neuropathy and diabetic ketoacidosis. Importantly, these associations appeared to reflect neuronal injury rather than Alzheimer’s-specific pathology, underscoring the need for longitudinal research to clarify how long-term glycemic exposure may affect brain health in people living with T1D.
Collectively, the findings emphasize the importance of optimal glycemic management not only for traditional diabetes outcomes, but also for long-term brain health. As blood-based biomarkers become increasingly accessible, this work lays the foundation for future studies aimed at identifying individuals at higher neurological risk and informing targeted interventions for people living with T1D.
The team reflects a highly collaborative, multi-institutional effort, with contributors from Washington State University, Rutgers University, Harvard Medical School and McLean Hospital, Mayo Clinic, the University of Pennsylvania, SUNY Upstate Medical University, AdventHealth Translational Research Institute, and other leading research centers across the United States.
Luciana Mascarenhas Fonseca, PhD, served as the study’s senior author while at WSU and is now at Rutgers University’s Brain Health Institute and Krieger Klein Alzheimer’s Research Center. Dr. Fonseca mentored Delgado throughout the project.