Longitudinal association between medication adherence and glycaemic control in Type 2 diabetes.

Aim Despite the widespread assumption that adherence drives glycaemic control, there is little published support for this in Type 2 diabetes. The study objective was to determine whether self-reported medication adherence predicts future glycaemic control in Type 2 diabetes, after accounting for baseline control. Methods Medication adherence (4-item Morisky scale), glycaemic control (HbA1c%), and other variables were assessed in 287 adult primary care patients prescribed oral medication (40% also on insulin) for Type 2 diabetes. Glycaemic control was reassessed 6 months later. Regression analyses examined concurrent and future glycaemic control as a function of baseline medication adherence after adjustment for baseline glycaemia and other potential confounders. Results Only half of patients reported high adherence. Cross-sectional adjusted analysis replicated prior reports of an adherence-HbA1c association ( P = 0.011). Even after adjusting for baseline HbA1c, each one-point increase in baseline Morisky total score was associated with a 1.8 mmol/mol (or 0.16%) increase in HbA1c measured 6 months later. Additionally, baseline endorsement of forgetting to take medication was associated with a 4.7 mmol/mol (or 0.43%) increase in 6-month HbA1c ( P = 0.005). This effect persisted after adjusting for psychological distress and did not vary by key demographic and medical features. Conclusions Even after stringent adjustment for baseline glycaemic control, self-reported adherence to diabetes medication predicts long-term glycaemic control. The Morisky scale is an easy-to-use clinical tool to identify patients whose glycaemic control will subsequently worsen, regardless of age, gender and psychological distress. [ABSTRACT FROM AUTHOR]