Randomized Controlled Trial of Simple Salt Reduction Instructions by Physician for Patients with Type 2 Diabetes Consuming Excessive Salt

Abstract

Objectives: We verified the clinical usefulness of an approach method in which a physician gives simple salt reduction instructions during outpatient visits to patients with type 2 diabetes. Methods: This study was an open-blind, randomized controlled trial. Subjects were outpatients with type 2 diabetes whose estimated salt intake using spot morning urine sample exceeded the target of salt intake. The control group (CG) was notified only of the current salt intake, whereas the intervention group (IG) was given the brief salt reduction instruction by a physician in addition to the information regarding their current salt intake. Results: The change in estimated salt intake was -0.6 g (from 10.1 to 9.5 g, p = 0.029) in the CG after 8 weeks, and -0.9 g (from 10.1 to 9.2 g, p = 0.001) in the IG, although there were no significant differences between them (p = 0.47). After 24 weeks, both groups no longer differed significantly from the baseline. In addition, multivariate linear regression analyses indicated that high salt intake and low estimated glomerular filtration rate at baseline were significantly associated with salt reduction after 8 weeks. Conclusions: Salt-reducing effects were observed after 8 weeks in both the IG and CG, but no significant difference was observed. Moreover, patients with high salt intake and renal disfunction may be more effective in accepting salt reduction instructions. Making patients aware of the importance of salt reduction through a physician is effective for continuous salt reduction, and it is important to continue regular and repetitive guidance.

Keywords: hypertension; nutritional instructions; randomized controlled trial; salt intake; salt restriction; type 2 diabetes mellitus.

Figure 1

Changes at 8 and 24 weeks from baseline. Changes at 8 and 24 weeks from baseline were compared between the intervention group (IG) and control group (CG) using mixed models for (A) estimated salt intake, (B) systolic blood pressure (SBP), (C) diastolic blood pressure (DBP), (D) estimated glomerular filtration rate (eGFR), and (E) HbA1c. (* p < 0.05, ** p < 0.001) Solid line: intervention group (IG), dotted line: control group (CG).

Figure 2

Subgroup analysis of changes in estimated salt intake. Changes in estimated salt intake 8 and 24 weeks after baseline were analyzed in the following subgroups: (A) age, (B) gender, (C) with or without antihypertensive drugs, and (D) HbA1c. A mixed model was used for the analysis. (* p < 0.05, ** p < 0.001). Solid line: IG, dotted line: CG.