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.

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 AUC 0 - 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.