Blood glucose levels and glycaemic burden in 76,341 patients attending primary care: Bittersweet findings from a 9-year cohort study

Aims: Diabetes care is principally applied in the primary care setting whereby we examined trends in glycaemic levels and goals and estimated avoidable glycaemic burden.

Methods: We retrieved glycated haemoglobin (HbA_1C) results and glucose-lowering prescription records from a patient-based medical database during 2005-2013. There were 275,480 available HbA_1C measurements from 76,341 individuals managed by 960 general practitioners from 321 clinics across Australia. Change in mean levels and glycaemic control over time were assessed according to sex, age and glucose-lowering therapy. The time that HbA_1C levels exceeded 7% (53mmol/mol) in untreated (n=4888), non-insulin (n=11,534) and insulin treated (n=4049) patients was calculated as area under the curve (AUC) and months above threshold.

Results: Average age of patients was 62.1±15.1years (47.1% women). HbA_1C levels decreased from 7.1% (54mmol/mol) in 2005 to 6.6% (49mmol/mol) in 2013 and the proportion of patients who achieved a HbA_1C target of <7% improved by 16% in men (53-69%) and 21% in women (55-76%). HbA_1C levels decreased with advancing age in men and increased with insulin treatment; correspondingly, HbA_1C goal attainment increased and decreased, respectively. Avoidable glycaemic burden was 9.3±17.7months in untreated, 16.2±25.2months in non-insulin, and 26.8±34.6months in insulin-treated patients.

Conclusions: Amid considerable improvements, many treated patients still do not attain HbA_1C levels ≤7% and time spent above this threshold was delayed. Earlier and more vigorously intensified management may reduce lengthy periods of uncontrolled hyperglycaemia in primary care.