1378-P: The Association between Baseline Hemoglobin A1c (A1C) and Risk of Progression from Prediabetes to Diabetes across Adult Age Groups

Introduction & Objectives: While A1c is a strong predictor of conversion from prediabetes to type 2 diabetes, it is unclear whether A1c values within the prediabetes range confer the same risk of conversion to type 2 diabetes within different adult age groups.

Methods: Using linked population-based administrative health databases, we investigated the progression from prediabetes to diabetes among adults (≥20 years) with laboratory criteria for prediabetes living in Ontario, Canada between 2012-2022. New diabetes cases were captured using a well-validated administrative data algorithm. Competing risk and Cox proportional hazards models were used to assess the association between A1c increments (~0.2%) within the prediabetes range (5.70-6.49%, vs <5.7%) and diabetes incidence in different decades.

Results: Among 3,022,169 individuals with prediabetes, 139,450 (4.6%; mean age 54.1 ± 15.8 yrs) progressed to diabetes over a mean follow up of 4.78 years. The cumulative incidence of diabetes was greatest among those with baseline A1C levels of 6.30-6.49% in both younger (20-29 yrs: 34.5%) and older adults (≥70 yrs: 19.2%). Increased A1c conferred a far greater relative risk of progression to diabetes in adults aged 20-29 and 30-39 (A1c 6.30-6.49%: HR 51.7, 95% CI 45.0-59.3 and HR 41.3, 38.8-44.0, respectively). Relative conversion rates were more modest in adults aged ≥70 years across all A1c categories (A1c 6.30-6.49%: HR 9.7, 9.3-10.1).

Conclusion: Baseline A1c was a stronger predictor of conversion from prediabetes to diabetes among younger adults, suggesting that diabetes prevention efforts should consider baseline A1C and age to reduce future risk of progression.