Effectiveness of primary care-led low-carbohydrate diet and self-management advice on glycaemic control in individuals with type 2 diabetes mellitus: protocol of a cluster randomised controlled trial.

Introduction: 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.

Methods and analysis: 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 (<130 g/day) (ii) diabetes self-management principles. A primary care nurse will deliver the intervention at baseline, 3, 6, 9 and 12 months.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.

Ethics and dissemination: 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.

Trial registration number: Clinical Trials Registry-India (CTRI/2024/02/062202).