INTRODUCTION: Type 2 diabetes mellitus (T2DM) is a common chronic condition with significant health and socioeconomic consequences. In Nepal, T2DM is a common disease for which people consult ayurvedic (traditional medical system) practitioners and use ayurvedic medicines. Strong concerns remain about the suboptimal T2DM management of many patients by ayurvedic practitioners, and therefore, based on the best available scientific evidence, we have developed a clinical guideline for managing T2DM by ayurvedic practitioners. The research question to be addressed by a definitive cluster randomized controlled trial (RCT) is whether the introduction of a clinical guideline can improve the management of T2DM by ayurvedic practitioners in Nepal as compared to usual ayurvedic management (i.e., without any clinical guideline). In preparation for this future work, this current study aims to determine the feasibility of undertaking the definitive cluster RCT. METHODS: This is a 2-arm, feasibility cluster RCT with a blinded outcome assessment and a qualitative evaluation. The study is conducted in 12 public and private ayurveda centers in and outside the Kathmandu Valley in Nepal (1:1 intervention:control). Eligible participants should be new T2DM adult patients (i.e., treatment naïve) - the glycated hemoglobin level should be 6.5% or above but less than 9%. At least 120 participants (60/group) will be recruited and followed up for 6 months. Important parameters, needed to design the definitive trial, will be estimated, such as the standard deviation of the outcome measure (i.e., glycated hemoglobin level at 6-month follow-up), intraclass correlation coefficient, cluster size, recruitment, the time needed to recruit participants, follow-up, and adherence to the recommended ayurvedic medicine. Semi-structured qualitative interviews will be conducted with around 20 to 30 participants and all the participating ayurvedic practitioners to explore their experiences and perspectives of taking part in the study and of the intervention and a sample of eligible people declining to participate in the study to explore the reasons behind nonparticipation. DISCUSSION: We are now conducting a feasibility cluster RCT in Nepal to determine the feasibility of undertaking the definitive cluster trial. The first participant was recruited on 17 July 2022. If the feasibility is promising (such as recruitment, follow-up, and adherence to the recommended ayurvedic medicine), then the parameters estimated will be used to design the definitive cluster trial. Decisions over whether to modify the protocol will mainly be informed by the qualitative data.