White coat adherence (WCA) is defined as an increased adherence to treatment regimens in the days prior to the visit with a healthcare provider. Little is known on the effect of WCA on glucose control in adult patients with diabetes mellitus. Continuous glucose monitoring (CGM/FGM) provides a novel approach for a detailed analysis of a potential WCA effect on glycemia.
The present study is based on CGM/FGM-data of 279 patients with diabetes treated between January 2013 and July 2018 in a tertiary referral center. The analysis compares data from the 3 days prior to a visit (p1) with the preceding 25 days (p2). Patients were included in the analysis if CGM-/FGM-data were available for at least 50% of the two single time periods, resulting in a total of 817 data sets.
Sensor use was higher during p1 than p2 (89.8±10.7% [53mmol/mol] vs 83.0±13.0%; p<0.001). Mean glucose [MG] and coefficient of variation [CV] were lower in p1 compared to p2 (MG 167.1±44.8 mg/dL vs 168.8±38.8 mg/dL, p=0.046; CV 33.4±8.7% vs 36.0±7.1%, p<0.001; respectively). Time in range (70-180mg/dL) was higher in p1 than p2 (60.2±22.1% vs 59.1±19.0%, p=0.014). Sensitivity-analysis showed a predominant WCA effect in patients with HbA1c > 7% (53mmol/mol).
The present study reveals a statistically significant WCA effect on pre-visit glucose control. The absolute effect-size was comparably small, indicating that CGM/FGM data from the time period immediately before a clinical visit reliably reflects glycemic control of a longer pre-visit period.