HbA1c Evidence for a Prediabetes Diagnosis Delays Onset of Type 2 Diabetes

Abstract

Objective: This study examined the influential role of making a prediabetes diagnosis resulting in the subsequent delay in onset of type 2 diabetes. Research Design and Methods: Using electronic medical records, a multivariable logistic regression model examined demographic and clinical risk factors associated with a prediabetes diagnosis among patients with HbA1c evidence of prediabetes. A multivariable non-proportional Cox regression examined development to type 2 diabetes (maximum 7 year follow-up). Results: Analysis includes 40,970 patients with incident prediabetes (76.8% undiagnosed). Logistic regression showed higher baseline HbA1c levels significantly influenced assigning a prediabetes diagnosis: compared to patients with HbA1c level 5.7-5.9% (low), OR 1.66 (99% CI 1.54-1.78) for HbA1c level 6.0-6.2% (medium) and OR 1.62 (CI 1.43-1.83) for HbA1c level 6.3-6.4% (high). Cox model results, which included an interaction between HbA1c and prediabetes diagnosis, found HbA1c the most significant predictor. Patients with diagnosed prediabetes progressed to type 2 diabetes slower than those undiagnosed. Comparing diagnosed patients to undiagnosed within the same HbA1c level, HRs ranged from 0.47 (CI 0.37-0.61) in the high HbA1c level to 0.83 (CI 0.67-1.02) in the low HbA1c level. Conclusions: From the LEADR cohort (1) HbA1c levels were the principle factor associated with risk for prediabetes diagnosis. Modeling development to diabetes, baseline HbA1c was the significant predictor of risk. Findings suggest assignment of a prediabetes diagnosis is associated with slower development of diabetes and this protective benefit of being diagnosed increases with a higher baseline HbA1c. Prediabetes diagnosis is useful for delaying onset of type 2 diabetes.