Trends and disparities in diabetes prevalence in Ontario, Canada between 2015-2021

Background — The rising prevalence of diabetes disproportionately impacts socially-disadvantaged communities. We aimed to determine whether trends of diabetes prevalence vary by age, sex, and neighbourhood socioeconomic status (SES).

Methods — We conducted a population-based cross-sectional time-series analysis using health administrative data for adults aged ≥20 years (>90% type 2 diabetes) from 2015 (N=10,935,448) to 2021 (N=11,885,060). Annual crude and age-sex standardized prevalence rates were estimated using a validated administrative case definition. Neighbourhood SES was measured using the Material Deprivation Domain of the Ontario Marginalization Index and categorized into quintiles (Q1 least deprived to Q5 most deprived).

Results — Age-sex standardized prevalence of diabetes increased nearly 6% from 10.8 in 2015 to 11.4% in 2021. Increases were consistent across all age and sex groups, with the largest relative increases among adults aged 20-34 years (males +17.1%, females +11.3%). Diabetes prevalence rose across all neighbourhood deprivation quintiles, remaining highest in the most deprived areas from 2015 to 2021 (13.3% to 14.1%). Relative increases ranged from 5.8% in the most deprived areas to 7.1% in the least deprived areas. A clear socioeconomic gradient was observed where diabetes prevalence was 42% higher in the most deprived neighbourhoods (Q5 RR 1.42, 95% CI 1.41-1.44; all p<0.0001) compared to the least (Q1) deprived areas, underscoring the structural nature of diabetes inequities.

Conclusions — Diabetes prevalence continues to increase in the lowest income areas, calling for more tailored and culturally sensitive policy interventions and programs to reduce the future burden of diabetes among populations living with social disadvantage.