A Time-To-Event Analysis to Conceptualize and Predict Delay in Type 2 Diabetes Diagnosis in Primary Care

Background: Delayed diagnosis of Type 2 diabetes (T2D) contributes to the development of diabetes-related health complications. Although signs of T2D are commonly identified in primary care, delays in diagnosis remain a significant challenge. The relationship between patient-level factors (e.g., demographics and healthcare utilization patterns), practice-related factors (e.g., primary care location), and the time to T2D diagnosis represents a critical, yet understudied, research area. Methods: We conducted a retrospective observational cohort study of 736 adults who received care from two primary care clinics within an integrated healthcare system in the mid-Atlantic region of the United States (2017--2023). Kaplan--Meier survival analysis and Cox proportional hazards models quantified diagnostic delays from the first elevated hemoglobin A1c (HgA1c \((\ge)\)5.7% [39\,mmol/mol]) to documented T2D diagnosis. Patient features, primary care location, continuity of care and visit regularity were evaluated in multivariate models as potential contributors to diagnostic delay. A Markov cohort state-transition model characterized diagnostic pathways over one year following the initial abnormal HgA1c measurement. Results: Median time to formal T2D diagnosis varied significantly between the two primary care locations (10 months vs. 6.6 months) which highlighted practice-specific gaps in timely diagnosis. High continuity and regularity of primary care visits were significantly associated with shorter time to diagnosis. Markov cohort model revealed that 60.6% of individuals remained undiagnosed one year after the initial abnormal HgA1c. Conclusion: Our study highlights the role of clinical practice influencing diagnostic delay in T2D within primary care. Improved continuity and regularity of care accelerate the T2D diagnosis, while location-specific diagnostic disparities persist. These findings underscore the urgent need for targeted clinical and policy interventions aimed at improving patient engagement, strengthening continuity of care, and facilitating earlier diagnosis.