# The Effect of Increased Sodium Intake with a Carbohydrate-Rich Meal on Glucose Homeostasis in People without Diabetes after Roux-en-Y Gastric Bypass: a Proof-of-Concept, Randomized, Open-Label, Crossover Study

## TL;DR

This study tested if adding salt to a carb-rich meal affects blood sugar in people who had gastric bypass surgery, finding a small reduction in peak blood sugar but no major impact overall.

## Contribution

This is the first study to investigate the effect of sodium supplementation on glucose homeostasis after Roux-en-Y gastric bypass in non-diabetic individuals.

## Key findings

- Adding 2 g of NaCl lowered peak postprandial glucose but not nadir glucose after Roux-en-Y gastric bypass.
- Sodium supplementation had no significant effect on insulin, c-peptide, or GLP-1 levels after the meal.
- Overall glucose homeostasis was not substantially altered by the addition of sodium chloride.

## Abstract

Roux-en-Y gastric bypass (RYGB) induces substantial weight loss and changes in glucose homeostasis, partly through alterations in gastrointestinal anatomy and nutrient absorption. Sodium-glucose co-transporters-1 (SGLT-1) facilitate intestinal glucose absorption, a process that may be compromised post-RYGB. Animal studies suggest that sodium supplementation to a meal may enhance SGLT-1 activity post-RYGB. In this study, we investigated whether adding sodium chloride (NaCl) to a carbohydrate-rich meal affects glucose homeostasis in people after RYGB.

In this open-label, randomized, crossover study, eleven adults without diabetes post-RYGB (mean age 57.3 ± 11.3 years, BMI 35.1 ± 7.5 kg/m2, 64% female) underwent two mixed meal tolerance tests (MMTT), on separate days, either with or without 2 g of additional NaCl (785 mg sodium). The primary outcome was the difference in nadir postprandial plasma glucose between conditions. Secondary outcomes included differences in area under the curve (AUC 0 − 180‘), fasting and peak plasma glucose, insulin, c-peptide and glucagon-like peptide-1 (GLP-1) concentrations.

The addition of 2 g NaCl did not alter nadir plasma glucose (3.7 mmol/L with NaCl vs 3.5 mmol/L without NaCl, 95% CI: -0.50 to 0.30, p = 0.55), fasting glucose or AUC0 − 180’ glucose. However, peak plasma glucose was lower with NaCl (7.8 vs 8.3 mmol/L, 95% CI: -0.88 to -0.08, p = 0.02). No differences were observed in AUC 0 − 180’, fasting and peak insulin, c-peptide and GLP-1 concentrations between the conditions.

In individuals post-RYGB without diabetes, sodium supplementation during a carbohydrate-rich meal did not substantially affect glucose homeostasis, although it appeared to reduce peak postprandial plasma glucose. Further studies are warranted to explore the clinical relevance of this effect.

The online version contains supplementary material available at 10.1007/s11695-025-08420-4.

2 g of NaCl with a meal lowered peak but not nadir postprandial glucose after RYGB.

2 g of NaCl with a meal did not influence postprandial insulin, c-peptide, or GLP-1.

2 g of NaCl with a meal had limited impact on overall glucose homeostasis after RYGB.

The online version contains supplementary material available at 10.1007/s11695-025-08420-4.