(145) Misdiagnosis of Adult-Onset Type 1 Diabetes and associated DKA Risk and Timing in Adults with Autoimmune Risk Factors

Background: : Type 1 diabetes mellitus (T1DM) in adults is often misdiagnosed as type 2 diabetes mellitus (T2DM) given the higher background prevalence of T2DM in adulthood. This misdiagnosis can result in suboptimal glycemic control due to inadequate treatment with possible progression to diabetic ketoacidosis (DKA). Common autoantibody tests, such as anti-glutamic acid decarboxylase 65 (anti-GAD65), anti-islet antigen-2 (anti-IA2), and anti-zinc transporter 8 (anti-ZnT8), can help differentiate T1DM from T2DM; however, these diagnostic tests are often underused at the time of diagnosis. Adults with other autoimmune conditions, such as celiac disease or autoimmune thyroid disease, are at increased risk of developing T1DM. There is limited research exploring how often misdiagnosis occurs in these high-risk groups and how it relates to the occurrence and timing DKA.

Objective: : To evaluate the frequency of initial misclassification of adult-onset T1DM and compare DKA risk and timing by diagnosis status and high-risk factors.

Methods: : This retrospective cohort study will use electronic health records from a large integrated delivery system in Texas. Adults (≥18 years) with a first incident diabetes diagnosis between January 30, 2018, and July 30, 2022, will be included. Patients will be classified as misdiagnosed if were initially coded/treated as T2DM and subsequently meet T1DM criteria. T1DM and T2DM will be defined using ICD-10 codes, and patients are required to have at least two ICD-10 codes for the respective condition. The index date will be the first documented diabetes diagnosis, and patients will be followed from index until T1DM confirmation, death, loss to follow-up, or study end. Two groups will be compared for outcomes: patients with T1DM misdiagnosed as T2DM and patients with T1DM without misdiagnosis. The primary outcome will be time to DKA, analyzed using a Cox proportional hazards model. Secondary outcomes will assess the total number of DKA events before correct diagnosis and autoantibody testing utilization. Analyses will be stratified by predefined high-risk factors, including coexisting autoimmune conditions such as autoimmune thyroid disease and celiac disease.

Results: : Results In Progress

Conclusions: : Conclusions In Progress

Sponsorship:: Baylor Scott and White Health