Evaluation of the efficacy of simplified nutritional instructions from physicians on dietary salt restriction for patients with type 2 diabetes mellitus consuming excessive salt: protocol for a randomized controlled trial

Background: Hypertension is present in more than 50% of patients with type 2 diabetes mellitus. Dietary salt restriction is recommended for the management of high blood pressure. Instructions on dietary salt restriction, provided by a dietitian, have been shown to help patients reduce their salt intake. However, appointments for the dietitians in hospitals are often already fully booked, making it difficult for patients to receive instructions on the same day as the outpatient clinic visit.

Aim: The aim of this trial is to test a new intervention to assess whether guidance on dietary salt restriction provided by physicians during outpatient visits is effective in reducing salt intake in patients with type 2 diabetes mellitus who have an excessive salt intake.

Methods: In this unblinded randomized controlled trial (RCT), a total of 200 patients, male or female, aged between 20 and 90 years, who have type 2 diabetes mellitus and consume excessive salt will be randomly assigned to two groups: an intervention group and a control group. In addition to being given routine treatment, participants in the intervention group will be given individual guidance on restricting their dietary salt intake by a physician upon enrollment. The control group will only be given routine treatment. Participants will be followed up for 24 weeks. The primary outcome will be dietary salt intake, which will be assessed at baseline and at 8, 16, and 24 weeks. The secondary outcomes, including body weight, body mass index, hemoglobin A1c level, blood pressure, blood glucose level, serum lipid profile, and urinary albumin excretion level, will be assessed at baseline and at 8, 16, and 24 weeks.

Discussion: The results of this RCT have the potential to provide a simple and novel clinical approach to reduce salt intake among patients with type 2 diabetes, making regular visits to their physician, in outpatient facilities. This protocol will contribute to the literature because it describes a practical intervention that has not been tested previously, and it may serve as guidance to other researchers interested in testing similar interventions.

Trial registration: University Hospital Medical Information Network (UMIN), UMIN000028809. Registered retrospectively on 24 August 2017. http://www.umin.ac.jp.