Understanding Medication Adherence and Glycaemic Level in People With Type 2 Diabetes Across Countries: A Cross‐Sectional and Longitudinal Analysis of Medication Beliefs, Illness Perceptions, Resistance to Illness and Mood

BACKGROUND AND AIMS: Low medication adherence is prevalent in diabetes, and many adherence factors found are non-modifiable by interventions. Adherence interventions have limited effectiveness due to a lack of tailoring and understanding of common modifiable factors. Hence, this study aimed to identify common and distinctive factors associated with medication adherence and glycaemic levels among people with type 2 diabetes in Singapore and the United Kingdom (UK) using cross-sectional and longitudinal analyses of standardised measures. METHODS: Medication adherence, medication beliefs, illness perceptions, mood, and glycaemic level were assessed using validated questionnaires and glycated haemoglobin (HbA1c) among 550 participants. Regressions and multilevel models investigated factors associated with baseline and 3-6-month adherence and HbA1c. RESULTS: Overall, participants with greater resistance to illness (β = -0.084, p = 0.031), medication concern (β = -0.069, p = 0.026) and reduced understanding of diabetes (β = 0.105, p = 0.053) had lower baseline adherence. Participants with greater adherence (β = -0.088, p = 0.006), personal control (β = -0.154, p < 0.001) and reduced emotional impact (β = 0.076, p = 0.008) had lower baseline HbA1c. Perceived treatment control was associated with follow-up adherence (β = 0.140, p = 0.051), while personal control was associated with follow-up HbA1c (β = -0.092, p = 0.009). In Singapore, resistance to illness (β = -0.110, p = 0.011) and medication concern (β = -0.101, p = 0.006) were significant adherence factors. Participants with greater testing treatment tendency (β = 0.146, p = 0.028) and lower personal control (β = -0.132, p = 0.006) had higher HbA1c. In the UK, sensitivity to medication was related to adherence (β = -0.262, p = 0.019), while adherence (β = -1.020, p = 0.040) and personal control (β = -1.803, p = 0.001) were linked to HbA1c. CONCLUSIONS: Common factors, such as resistance to illness and perceived personal control, may affect medication adherence or glycaemic level. Distinctive factors associated with medication adherence or glycaemic level include perceived sensitivity to medication and testing treatment. The common and distinctive factors identified could be used to support broadly applicable and locally relevant personalised intervention development.