Differences in HbA1C at the time of diabetes diagnosis in the adult population of Ontario, Canada

Aims — To determine the proportion of adults with HbA_1c ≥ 8.0% (64 mmol/mol) at diabetes diagnosis, as an indicator of delayed diagnosis or less intensive screening.

Methods — We conducted a cross-sectional population-level study using clinical, administrative and immigration data from Ontario, Canada. We identified all individuals diagnosed with diabetes between June 2012 and June 2015, and determined the HbA_1c between 60 days prior to and 30 days after diagnosis. Individuals were stratified based on many sociodemographic, clinical and primary care characteristics, and the proportion with HbA_1c ≥ 8.0% (64 mmol/mol) was determined.

Results — Mean HbA_1c at diabetes diagnosis in the population was 7.3 ± 1.9% (56 ± 21 mmol/mol), and 21.1% had HbA_1c ≥ 8.0% (64 mmol/mol) at diagnosis. Factors for which there were important differences in the proportion with HbA_1c ≥ 8.0% (64 mmol/mol) included age, sex, ethnicity, comorbidities, frequency of primary care and primary care rostering.

Conclusions — In a real-world population-level setting, more than one-fifth of individuals diagnosed with diabetes have HbA_1c levels ≥8.0% (64 mmol/mol), suggesting a delay in diagnosis due to inadequate screening. Differences were found based on age, sex and clinical factors, but not based on socioeconomic or immigration factors.