Aims: Adopting effective self-care behaviors is essential in maintaining optimal glycated hemoglobin (HbA1c) levels. The study aimed to evaluate the effect of health literacy-based, health belief-constructed education and counseling on glycated hemoglobin (HbA1c) in people with type 2 diabetes. Methods: The parallel-group, randomized controlled study was conducted between June 2019 and March 2020. One hundred and twenty patients were randomized to receive either 12-week health literacy-based group education and phone counseling (intervention, 60 patients) or routine diabetic care (control, 60 patients). The study was completed with 107 patients (54 intervention, 53 control). HbA1c (primary outcome), self-efficacy, perceived susceptibility, severity, barriers, and benefits (secondary outcomes) were evaluated at baseline and six months. Results: Both groups had decreases in HbA1c. There was no significant decrease in HbA1c between the intervention and control groups. However, there was a significant improvement in self-efficacy, change in perceived susceptibility, perceived barriers, and perceived benefits in the intervention group. This effect was the same for all patients in the high and low health literacy intervention groups. Conclusions: Education and counseling based on health literacy levels and framed with health belief constructs change health beliefs, predicting higher engagement and efficacy in disease management activities. Clinical trial number: NCT04677127. (c) 2021 Published by Elsevier Ltd on behalf of Primary Care Diabetes Europe.