Decade-long diabetes monitoring reveals steady improvement in patient control
A Swedish laboratory's analysis of 722,000 HbA1c tests over 12 years shows patient blood sugar levels have improved significantly—dropping 10% at median—despite a major equipment change. The finding suggests diabetes management is working better over time, with implications for how hospitals track quality and adjust treatment protocols.
Originaltitel: Patient result monitoring of HbA<sub>1c</sub> shows small seasonal variations and steady decrease over more than 10 years
<p><strong>OBJECTIVES:</strong> Internal and external quality assurance materials often use highly processed matrixes. This can render the materials non-commutable. Monitoring laboratory methods with patient medians helps in identifying and correcting systematic errors that may affect diagnostic accuracy. The aim of the present study was to use HbA<sub>1c</sub> patient results for monitoring of method performance over time.</p><p><strong>METHODS:</strong> Test HbA<sub>1c</sub> results from 2010 to 2022 was analyzed (n=722,553) regarding changes over time and seasonal variation. The HbA<sub>1c</sub> testing was initially performed on a Cobas 501 instrument using immunological detection but in May 2017 the method was replaced by capillary electrophoresis on Capillarys 3 Tera.</p><p><strong>RESULTS:</strong> There was a steady decrease in HbA<sub>1c</sub> values. From 2011 to 2021 the decrease was for 0.10 percentile 6.6 %, lower quartile 7.9 %, median 10.2 %, mean values 9 %, upper quartile 11.2 %, and 0.90 percentile 9.3 %. No clear shift in HbA<sub>1c</sub> levels was observed due to the shift in methods. The median HbA<sub>1c</sub> values per month was approximately 44 mmol/mol (6.2 %, DCCT/NGSP). The only month with a median HbA<sub>1c</sub> that differed by more than 1 mmol/mol was July with a median value of 42 mmol/mol (6.0 %).</p><p><strong>CONCLUSIONS:</strong> The patient data showed a similar decrease as in the National Diabetes Register which indicates that the method is stable over time without any sudden changes and that the seasonal variation is low. The continuous decrease in HbA<sub>1c</sub> values over time is most likely to a shift towards earlier detection of patient with diabetes and improved treatment.</p>