Glycemic Improvement Despite Limited Weight-Loss Response in Adults with Obesity and High Cardiometabolic Burden: A Real-World Study from the Brazilian Amazon

Objective: Obesity and type 2 diabetes mellitus frequently coexist and require therapeutic strategies capable of addressing both excess adiposity and cardiometabolic risk. However, real-world evidence on whether improvements in cardiometabolic parameters are accompanied by clinically meaningful weight loss remains limited, particularly in public healthcare settings in the Brazilian Amazon. This study evaluated longitudinal changes in body weight and cardiometabolic parameters among adults with obesity receiving routine outpatient endocrinology care within the Brazilian Unified Health System and investigated the relationship between weight change, glycemic response, and factors associated with therapeutic target achievement. As a complementary metabolic analysis, longitudinal changes in the triglyceride–glucose (TyG) index, as a surrogate marker of insulin resistance, were also evaluated. Methods: This retrospective longitudinal observational study included 90 adults with obesity receiving routine outpatient endocrinology care within the Brazilian Unified Health System in Marabá, Pará, Brazil. Participants had at least six months of follow-up, with a mean follow-up duration of 14.3 ± 4.0 months. Changes in anthropometric, glycemic, blood pressure, and lipid parameters were evaluated between baseline and follow-up. The TyG index was calculated from fasting plasma glucose and triglyceride concentrations, with longitudinal TyG analysis restricted to participants with paired measurements available at baseline and follow-up. Standardized within-participant effect sizes were estimated using Cohen’s dz with bootstrap 95% confidence intervals (CIs). Spearman correlations were used to examine associations between percentage weight change and cardiometabolic changes. Multivariable logistic regression models evaluated factors associated with achieving HbA1c < 7.0% among participants with type 2 diabetes mellitus and ≥5% weight loss in the overall cohort. Results: Body weight changed minimally during follow-up (mean Δ = −0.47 kg; dz = −0.072; 95% CI −0.306 to 0.126), whereas HbA1c decreased by 1.00 percentage point (dz = −0.441; 95% CI −0.751 to −0.219). Small reductions were also observed in fasting plasma glucose (Δ = −31.53 mg/dL), LDL cholesterol (Δ = −15.79 mg/dL), and triglycerides (Δ = −35.30 mg/dL). Among 51 participants with complete paired fasting plasma glucose and triglyceride measurements, mean TyG decreased from 9.68 ± 0.85 to 9.29 ± 0.79 (mean Δ = −0.39; 95% CI −0.58 to −0.20; p < 0.001), with a moderate standardized within-participant effect (dz = −0.569; bootstrap 95% CI −0.881 to −0.301). Only 21/90 participants (23.3%) achieved ≥5% weight loss, while 44/90 (48.9%) gained weight. Among participants with paired HbA1c measurements, the proportion with HbA1c ≥7.0% decreased from 72.9% to 52.9%. Percentage weight change was not significantly correlated with changes in HbA1c (rs = −0.018; p = 0.882), fasting plasma glucose, or lipid parameters, nor with change in TyG (rs = −0.041; p = 0.776). Self-reported medication adherence was associated with a greater median reduction in HbA1c (−1.55 vs. 0.00 percentage points; p = 0.003) and higher adjusted odds of achieving HbA1c < 7.0% (OR = 3.58; 95% CI 1.08–11.86; p = 0.037) but was not associated with weight-loss response. No evaluated baseline characteristic was significantly associated with achieving ≥5% weight loss. Conclusions: In adults with obesity receiving routine outpatient endocrinology care within the Brazilian Unified Health System in the Brazilian Amazon, longitudinal follow-up was accompanied by modest improvements in glycemic and selected lipid parameters but minimal average weight reduction. The TyG index also decreased significantly among participants with paired measurements, consistent with improvement in this surrogate marker of insulin resistance; however, this finding should not be interpreted as direct evidence of improved insulin sensitivity or reduced cardiovascular risk. Clinically meaningful weight loss was achieved by fewer than one quarter of participants, and nearly half gained weight. Medication adherence was associated with better glycemic control but not with weight loss. These findings indicate that improvements in conventional and surrogate metabolic markers were not consistently accompanied by meaningful reductions in body weight and support the incorporation of weight-specific outcomes and comprehensive obesity-directed strategies into chronic disease care.