Both the frequency of HbA1c testing and the frequency of self‐monitoring of blood glucose predict metabolic control: A multicentre analysis of 15 199 adult type 1 diabetes patients from Germany and Austria

BACKGROUND The objective of this study was to examine the association between metabolic control and frequency of haemoglobin A1c (HbA1c ) measurements and of self-monitoring of blood glucose, as well as the interaction of both. METHODS Data of 15 199 adult type 1 diabetes patients registered in a standardized electronic health record (DPV) were included. To model the association between metabolic control and frequency of HbA1c testing or of self-monitoring of blood glucose, multiple hierarchic regression models with adjustment for confounders were fitted. Tukey-Kramer test was used to adjust P values for multiple comparisons. Vuong test was used to compare non-nested models. RESULTS The baseline variables of the study population were median age 19.9 [Q1; Q3: 18.4; 32.2] years and diabetes duration 10.4 [6.8; 15.7] years. Haemoglobin A1c was 60.4 [51.5; 72.5] mmol/mol. Frequency of HbA1c testing was 8.0 [5.0; 9.0] within 2 years, and daily self-monitoring of blood glucose frequency was 5.0 [4.0; 6.0]. After adjustment, a U-shaped association between metabolic control and frequency of HbA1c testing was observed with lowest HbA1c levels in the 3-monthly HbA1c testing group. There was an inverse relationship between self-monitoring of blood glucose and HbA1c with lower HbA1c associated with highest frequency of testing (>6 daily measurements). Quarterly HbA1c testing and frequent self-monitoring of blood glucose were associated with best metabolic control. The adjusted Vuong Z statistic suggests that metabolic control might be better explained by HbA1c testing compared to self-monitoring of blood glucose (P < .0001). CONCLUSION This research reveals the importance of quarterly clinical HbA1c monitoring together with frequent self-monitoring of blood glucose in diabetes management to reach and maintain target HbA1c .