PurposeLittle is known about predictors of adherence to diabetes medication in Saudi Arabia. This study aimed to investigate whether illness perceptions, beliefs about medicine, and God locus of health control beliefs were associated with adherence to medication and glycaemic control (HbA1c) in Saudi patients with type 2 diabetes (T2D).Patients and methodsA convenience sample of 115 adults with T2D were recruited from a diabetes outpatient clinic. Validated self-reported measures of adherence to medication, illness perceptions, beliefs about medicine, and God locus of health control were administered. Patients’ most recent HbA1c levels were extracted from medical records. Multivariable logistic and linear regressions were used to examine the association between illness perceptions, beliefs about medicine and adherence to medication and HbA1c.ResultsMore than two thirds of patients (69%) reported poor adherence to medication. All illness perceptions domains, beliefs about medicine, and God locus of health control beliefs were associated with adherence. Multivariable logistic regression revealed that older age (OR= 3.76, p= 0.023), worse consequences perceptions (OR= 0.21, p= 0.011), worse illness identity (OR= 0.23, p= 0.010), and greater illness coherence (OR= 3.24, p= 0.022) were independent predictors of adherence. Two thirds of patients (67%) had suboptimal HbA1c; and perceptions of a cyclical timeline and lower insulin effectiveness were associated with higher HbA1c. In multiple linear regression, perceptions of a cyclical timeline (β= 0.19, p= 0.040) were an independent significant predictor of HbA1c.ConclusionIn Saudi Arabia, patients’ perceptions of T2D, beliefs about medicine, and God locus of control beliefs are associated with adherence. These results inform the development of interventions based on the Common-Sense Model (CSM) to encourage improved adherence and glycaemic control among Saudi patients with T2D. Further research with larger and more diverse samples is warranted to expand the generalizability of these findings.