Table 2 Factors affecting adherence and persistence to metformin [19]

Difficulties in understanding the rationale for long-term metformin treatment

Poor health care team-patient relationship

Regimen complexity, especially in patients with multiple comorbid conditions

Difficulty swallowing; psychological difficulty swallowing tablets

Lack of times for in-depth communication with patient

Large size of or rough coating on metformin tablets

Memory problems (e.g., in older patients)

Lack of awareness of problems with treatment adherence

Inflexible treatment regimens

Socioeconomic factors (e.g., medication costs, lack of support during treatment)

Gastrointestinal side effects

Cultural attitudes and beliefs