Patient adherence to and tolerability of treatment with metformin extended-release formulation in patients with type 2 diabetes. GLUCOMP study

Introduction. Appropriate treatment of diabetes requires regular intake of recommended drugs. Multifactonal therapy, which necessitates the concomitant use of many medications, may decrease patient adherence. The purpose of the study was to assess type 2 diabetic patients' adherence to and tolerability of metformin extended-release formulation in the outpatient setting. Materials and methods. This non-interventional study was conducted in a group of 4737 patients [including 2468 (52%) women] with mean age of 60.6 +/- 9.4 years, diabetes duration of 5.6 +/- 4.4 years, duration of treatment with metformin extended release formulation of 8.3 +/- 12 months at an average dose of 1667 +/- 350 mg. The study enrolled patients aged over 18 years with type 2 diabetes if they were treated with metformin extended-release formulation at a dose of 1500-2000 mg for less than 1 year prior to the study enrollment. The exclusion criteria included: pregnancy, breast-feeding and any contraindications for metformin treatment. Treatment adherence was assessed by a tablet count (percentage of prescribed tablets taken) and using the Morisky-Green scale. Treatment adherence was defined as follows: excellent patient adherence if > 90% of prescribed tablets were taken; good: 76-90%; moderate: 51-75%; poor: 50%. Treatment tolerability was also evaluated based on the medical history focused on gastrointestinal symptoms, as well as patient preference for using specific types of metformin. Other patient data, clinical data and laboratory test results were recorded at the beginning of the study and after 3 months. Results. After 3 months of treatment with metformin extended release formulation 96% of study subjects demonstrated excellent or good adherence. Treatment adherence was significantly lower with 2 or 3 concomitant medications as compared to one (p < 0.001). Adverse events occurred in 715 patients (15% out of 4758 patients undergoing safety analysis). The occurrence of adverse events significantly decreased treatment adherence (p < 0.001). Approximately 90% of patients declared they had preferred the use of metformin extended-release formulation. Conclusions. Metformin extended-release formulation is a suitable, well tolerated therapeutic option which helps to obtain good patient cooperation based on good adherence.