A Longitudinal Examination of Patient Portal Use on Glycemic Control among Patients with Uncontrolled Type 2 Diabetes.

Abstract Aim This study examined glycemia level over a 2-year period between portal users and non-users. Methods This retrospective cohort study used data from electronic health records (EHRs) of a large academic medical center and its ancillary patient portal. A total of 15,528 patients with uncontrolled type 2 diabetes mellitus (T2DM) were included. Using propensity score matching (PSM), portal users and non-users were balanced on demographic and clinical characteristics. Mixed-effects polynomial regression modeling was employed to evaluate the HbA1c change over time between groups. Results The patient sample was 85.9% (13,333) white and 52.5% (7375) male. On average, patients were 62.8 (SD, 11.7) years old and with obesity (mean BMI: 34.2±7.2 kg/m2) with uncontrolled T2DM (initial HbA1c: 8.5±1.5%). After PSM, portal users (n=4924) and non-users (n=4924) were matched on all variables except for the insurance. The mixed-effects modeling showed a nonlinear decrease of HbA1c in both groups over time. A significant interaction was observed with a greater decline, followed by a smaller rise of HbA1c in portal users than non-users. Conclusions The use of the patient portal was significantly associated with a lower HbA1c. This finding supports patient portals as a promising tool for improving clinical outcomes in patients with uncontrolled T2DM.