Background and Aim: Self-care has a vital role in the control and prevention of complications in patients with Type-2 diabetes mellitus (T2DM), two important behaviors in self-care being medication adherence and physical activity. Regular physical activity has been shown to improve glycemic control, reduce blood pressure, reduce lipids and improve cardiorespiratory fitness in individuals with T2DM. In addition, medication adherence is a key factor in controlling and decreasing the risk of related complications. This study aimed to determine and predict the most important factors affecting the levels of physical activity and medication adherence in patients with T2DM based on the theory of planned behavior.

Materials and Methods: This cross-sectional study, based on the planned behavior theory, was performed on 160 selected men and women with T2DM referring to urban health centers in Yasuj, Iran in 2016; the selection was done by random cluster sampling. Data on medication adherence and physical activity were collected using questionnaires and analyzed using SPSS version 20 software, the statistical tests being descriptive statistics, Pearson correlation coefficient and multiple linear regression; a p<0/05 was considered to indicate statistical significance.

Results: Altogether, 45% and 43% of the patients had a low and medium level of physical activity, respectively, only 12% having an acceptable level. The adherence to medication was much better ─ 76% had a good adherence. As regards the planned behavior theory constructs, perceived behavior control had a significant relationship with physical activity and medication adherence. Results of multiple linear regression also showed that perceived behavior control was a predictive variable for physical activity level and medication adherence in the patients.

Conclusion: Based on the findings, which indicate that the most important construct is perceived behavior control as regards medication adherence and level of physical activity, it is concluded that it is vital to strengthen the self-care component of health programs and support such programs.