Refill adherence of antihyperglycaemic drugs related to glucose control (HbA_1c) in patients with type 2 diabetes

The aim of this study was to examine a potential association between: (1) refill adherence to antihyperglycaemic drugs and glucose control, and (2) adherence to antihyperglycaemic and cardiovascular drugs for the same patients. Consecutive patients with type 2 diabetes at six Swedish health centres were included. Refill adherence was determined from repeat prescriptions. Satisfactory refill adherence was defined as the percentage of the patients with refills covering ≥80% of the prescribed treatment time. A total of 994 prescriptions were collected from 422 patients, 346 patients had antihyperglycaemic drugs (mean HbA_1c 6.5%) and 76 were on diet and exercise but not on drugs (mean HbA_1c 6.2%) (P = 0.0098). A total of 257 patients (74%) had satisfactory refill adherence. Mean HbA_1c for the adherent patients was 6.5% and for the non-adherent patients 6.8% (P = 0.025). For patients on insulin only, 69% had satisfactory refill adherence with mean HbA_1c 6.6% compared to 7.3% (P = 0.005) for the non-adherent patients. Ninety-two percent of the patients with satisfactory refill adherence to antihyperglycaemic agents were also adherent to cardiovascular drugs compared to 62% among those who were non-adherent to antihyperglycaemic drugs (P < 0.001). Patients with satisfactory refill adherence have lower HbA_1c-levels and higher adherence to cardiovascular drugs than non-adherent patients.