Understanding factors influencing medication adherence in Type 2 diabetes guided by the COM-B behaviour change model...

Type 2 Diabetes Mellitus (T2DM) requires a multifaceted management approach involving lifestyle modifications, education, and pharmacological treatments. Medication adherence is critical for achieving glycaemic control; however, up to 45 % of patients fail to meet HbA1c targets. The Morisky Medication Adherence Scale (MMAS) is a validated tool widely used in clinical practice to assess self-reported medication adherence, offering valuable insights into patient behaviours affecting treatment outcomes.

This systematic review evaluates medication adherence in adults with T2DM using the MMAS and to identify modifiable factors influencing non-adherence. The COM-B model was used to structure the analysis by mapping barriers and enablers to the Capability, Opportunity, and Motivation components that underpin medication-taking Behaviour.

A systematic review was conducted following the PRISMA framework. MEDLINE, EMBASE, EMCARE, and Ovid Nursing databases were searched for cross-sectional studies published between January 2013 and December 2024 that utilised the MMAS scale to assess adherence in adults with T2DM receiving oral or injectable anti-glycaemic therapies. A narrative synthesis was conducted using the COM-B model to identify key barriers and enablers influencing adherence.

Of 9990 records screened, 30 studies from 17 countries, involving 8405 participants, met the inclusion criteria. Overall, 40.9 % of participants demonstrated high adherence, while 42.6 % had low adherence. Key barriers included poor diabetes knowledge, depression, polypharmacy, side effects, inadequate patient-provider communication, and lack of continuity in care. Enablers encompassed patient education, family support, effective patient-provider communication, and structured diabetes education programmes.

The MMAS remains a reliable tool for assessing self-reported medication adherence in T2DM. However, adherence levels remain suboptimal. Addressing modifiable factors, such as depression, enhancing diabetes education, and improving healthcare communication, may improve adherence, glycaemic control, and overall T2DM management outcomes.

Registered with PROSPERO (CRD42022359969).