Triglyceride-glucose index as a predictor of body composition changes in patients undergoing bariatric surgery

The triglyceride-glucose index (TyG) is a practical marker for assessing insulin resistance. This study evaluates the ability of the TyG index to predict body composition changes in patients following bariatric surgery.

A retrospective cohort study of 190 participants (45 diabetics, 89 pre-diabetics, and 56 normal glycemic) undergoing bariatric surgery at Sina Hospital from 2024 to 2025 was conducted. Body composition was measured via bioelectrical impedance analysis (BIA) at baseline, 3- and 6-months post-surgery. The main outcome was the association between baseline TyG levels and changes in body composition. Subgroup analyses were performed based on glycemic status.

Among diabetics, baseline TyG negatively correlated with free fat mass (rho=-0.427, p = 0.005), basal metabolic rate (rho=-0.733, p = 0.002), and total body water (rho=-0.441, p = 0.005) at 3-months post-surgery. Pre-diabetic and normoglycemic participants showed similar negative associations between baseline TyG and fat mass changes at 3 months (rho=-0.250, p = 0.023 and rho=-0.348, p = 0.011) and 6 months (rho=-0.228, p = 0.036 and rho=-0.436, p = 0.002) post-surgery. Weight and body mass index also demonstrated significant negative correlations with baseline TyG. Additionally, TyG index significantly decreased at both 3- and 6-months across all subgroups.

The TyG index appears to be a useful predictor of body composition changes after bariatric surgery, particularly among patients with diabetes. The significant alterations observed in the TyG index within the first 3- and 6- months post-surgery suggest its potential as a marker of metabolic health in bariatric interventions.

The online version contains supplementary material available at 10.1007/s40200-026-02001-7.