Can salt substitutes lower blood pressure in diabetes? A new Cochrane review aims to find out

By Priyanjana Pramanik, MSc.Reviewed by Susha Cheriyedath, M.Sc.Jun 18 2025

With global hypertension and diabetes on the rise, researchers are investigating whether switching to potassium- or magnesium-based salts can help manage blood pressure without sacrificing taste or adherence.

Study: Sodium salt substitution for blood pressure in adults with diabetes. Image Credit: luchschenF / Shutterstock

In a recent research protocol published in the Cochrane Database of Systematic Reviews, researchers described their methods to systematically evaluate whether replacing regular sodium salt with substitutes such as potassium chloride, magnesium chloride, or other edible salts can reduce blood pressure in people with diabetes mellitus.

Their analysis will focus on changes in systolic, diastolic, and mean arterial blood pressure as the outcomes of interest, aiming to clarify both the benefits and harms of replacing common salt in the diet for people with this condition.

Dual burden of diabetes and hypertension

Hypertension (high blood pressure) is one of the leading causes of global illness and death, contributing significantly to cardiovascular diseases like heart attacks, strokes, and heart failure.

The World Health Organization estimates that by 2025, around 1.6 billion people worldwide will be living with hypertension, with a large proportion in low- and middle-income countries.

Diabetes mellitus, another major public health challenge, often coexists with hypertension. In people with diabetes, physiological changes such as increased fluid volume and vascular resistance make them particularly prone to high blood pressure, which further raises their risk for severe cardiovascular complications.

Potential for substituting table salt

Reducing dietary salt intake is a widely recommended and tested lifestyle strategy for controlling blood pressure. However, people vary in how strongly their blood pressure responds to sodium reduction, and adherence to a low-sodium diet can be challenging.

Besides simply cutting salt, substituting regular table salt (sodium chloride) with salts richer in potassium or magnesium has shown promise in lowering blood pressure in the general population.

Magnesium and potassium play important roles in regulating vascular tone and fluid balance. Evidence suggests that people with diabetes often have lower levels of these minerals, which may worsen blood pressure control.

Salt substitutes that combine reduced sodium with increased potassium and magnesium may offer a practical way to lower blood pressure without requiring drastic changes in diet or taste.

Substitutes have shown good consumer acceptance in taste trials, including national studies such as the Dutch Food Survey and a triangle test in Peru. For people with diabetes, who struggle with both high blood pressure and low potassium or magnesium levels, salt substitution could be a particularly useful intervention.

Despite existing guidelines such as those from the American Diabetes Association recommending reduced sodium and increased potassium intake via dietary approaches like DASH, there is a lack of clear, high-quality evidence specifically focused on salt substitution in diabetic populations.

Study objectives and methods

This review aims to assess whether substituting regular sodium salt with other edible salts, such as potassium chloride or magnesium chloride, effectively lowers blood pressure in adults with type 1 or type 2 diabetes mellitus. The primary focus is on measuring changes in systolic and diastolic blood pressure using standardized methods.

To achieve this, the review will follow Cochrane’s guidelines and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 reporting standards. It will include randomized controlled trials (RCTs) and quasi-randomized controlled trials (quasi-RCTs) that compare a diet with substitutes to regular sodium with a regular sodium salt diet, a sodium-restricted diet, or no intervention. Eligible studies must measure salt intake using 24-hour urinary excretion.

Participants will be adults with type 1 or type 2 diabetes, excluding pregnant women to ensure the review focuses solely on type 1 and type 2 diabetes mellitus. Studies with other comorbidities can be included if data for the diabetic subgroup are available. Trials must last at least one week.

Primary outcomes include changes in mean, diastolic, and systolic blood pressure. Secondary outcomes will cover withdrawals, adverse effects, changes in blood and urinary markers (glucose, creatinine, albumin, magnesium, potassium, and sodium), treatment adherence, and quality of life. The review will include both narrative and quantitative syntheses where appropriate data are available.

Systematic review process

This systematic review will comprehensively identify and analyze studies evaluating the effects of salt substitution on blood pressure in individuals with diabetes. An experienced Information Specialist will search major electronic databases without restrictions on language or publication status.

Bibliographies of relevant studies and systematic reviews will also be screened, and retraction checks will be performed via established retraction sources. Two authors will independently screen abstracts, titles, and full texts, extract data using standard templates, and assess the risk of bias using Cochrane’s RoB 1 tool.

Extracted data will include participant demographics, intervention details, study design, and outcomes, such as quality of life, biochemical markers, urinary excretion levels, changes in blood pressure, and adverse events.

For analysis, treatment effects will be measured as mean differences or risk ratios with 95% confidence intervals, applying a random-effects meta-analysis if studies are sufficiently homogeneous.

Subgroup and sensitivity analyses will explore factors such as the type of salt substitute, trial duration, comparator, type of diabetes, and the use of other interventions. The certainty of evidence will be assessed using the GRADE approach, considering study limitations, inconsistency, indirectness, imprecision, and publication bias.

The protocol notes that health equity will not be assessed as part of this review.