Dietary modification, particularly low-carbohydrate diet, and diabetes self-management education (DSME) have shown promise in improving glycaemic control among persons with type 2 diabetes mellitus (T2DM). However, real-world evidence from India is limited. This protocol describes the methods of a cluster randomised trial to determine the effectiveness and feasibility of adopting a low-carbohydrate diet among persons with T2DM.

Our cluster-randomised trial with a mixed-method process evaluation will use computer-generated block randomisation sequence to randomise Urban Primary Health Centres (UPHCs) (n=16) to either continue delivering the usual guideline-based care under the National Programme for Prevention and Control of Non-Communicable Diseases (NPNCD) or our study intervention. The study intervention will comprise a personalised nutrition counselling focusing on (i) low-carbohydrate diet (

We will include persons with T2DM, over the age of 30 years and above, irrespective of comorbidities, registered in the selected UPHC under care for diabetes for at least a month and with an glycated haemoglobin (HbA1c) level ≥6.5% during the screening test. We will collect data electronically using semistructured questionnaires and measure HbA1c, blood pressure, lipid profile, serum creatinine and body weight at baseline, 3, 6, 9 and 12 months after enrolment. We will use a difference in difference analysis, adjusted for clustering, to compare the change in HbA1c at the follow-up visits compared with baseline across the two study arms. We will conduct both intention-to-treat and per-protocol analysis, exploring reasons for differences in effect size.

The study protocol was reviewed and approved by the Scientific Advisory Committee/Institutional Human Ethics Committee of the research institution (NIE/IHEC/202302-03). The findings of this study will be disseminated through publication in peer-reviewed journals.

Clinical Trials Registry-India (CTRI/2024/02/062202).