2293-P: Increased Risk for Dementia in the Setting of Traumatic Brain Injury (TBI) in Type 2 Diabetes (T2D) Patients

Introduction and Objective: Persons with T2D are at high risk for dementia, and TBI may further increase that risk. Past studies of dementia in those with diabetes and TBI are small in size and/or limited to type 1 diabetes. We used the large Veterans Affairs Health Care System to examine differences in patient characteristics and dementia risk in newly diagnosed T2D patients with and without TBI. Methods: Date of first T2D diagnosis was the index date and all-cause dementia (ACD) the outcome. Patients with ACD at baseline or within the 1st year, and those with TBI diagnosed after the index date were excluded. Characteristics at the index date were extracted and TBI patients were each matched to 30 non-TBI patients on age, sex, and index calendar year bins. We compared ACD risk between TBI/non-TBI patients with Kaplan-Meier plots and Cox proportional hazards models. Results: From 320,650 T2D patients, 10,540 had prior TBI and 15,924 developed ACD with median onset time 6.5 years (median censoring time = 8.4 years). TBI patients had more comorbidities, cardiovascular medications, and smokers (panel A), and developed ACD onset sooner (panel B). When further adjusting these matched groups for race, ethnicity, and specific index year, TBI remained associated with higher ACD risk (hazard ratio 2.0; 95% confidence interval 1.9-2.1). Conclusion: Our data suggest that newly diagnosed T2D with TBI have more diabetes complications and increased ACD risk, highlighting a particularly high-risk group. Disclosure D. Tjandra: None. S. Macwan: None. D.R. Miller: None. J. Zhou: None. P. Reaven: Research Support; Current; Dexcom, Inc., Lilly Global Health Partnership. Funding U.S.