One-Hour Post-Load Glucose Is Associated with Multisystem Complications in People Living with Obesity

Background: Obesity is associated with a broad range of complications that frequently develop before the onset of type 2 diabetes mellitus (T2DM). Identifying early metabolic markers associated with such complications is essential for improving risk stratification and supporting complication-driven therapeutic strategies. Plasma glucose measured at 1 h during the oral glucose tolerance test (OGTT) has emerged as a sensitive marker of early dysglycemia and adverse cardiometabolic outcomes, but its relationship with established obesity-related complications in individuals without diabetes remains incompletely characterized. We aimed to investigate the association between 1 h post-load plasma glucose levels during OGTT and obesity-related complications in adults living with obesity without T2DM. Methods: This observational cross-sectional study included 47 adults with obesity evaluated during their first visit to obesity clinics. Individuals with T2DM or prior use of anti-obesity pharmacotherapy were excluded. All participants underwent a standard 75-g OGTT with plasma glucose and insulin measurements at fasting, 1 h, and 2 h. Obesity-related complications were recorded retrospectively through structured questionnaires, clinical assessment, and medical record review. Between-group comparisons were performed using non-parametric tests, and repeated OGTT measurements were analyzed using non-parametric longitudinal models. Results: Higher 1 h post-load glucose levels were observed in participants with arterial hypertension (p < 0.001), dyslipidemia (p = 0.020), metabolic dysfunction-associated steatotic liver disease (p = 0.005), impaired glucose tolerance (p = 0.027), obesity hypoventilation syndrome (p = 0.039), urinary incontinence (p = 0.038), and chronic kidney disease (p = 0.048). In most comparisons, 1 h post-load glucose demonstrated stronger discriminatory capacity than fasting or 2 h glucose values. Insulin levels increased markedly after glucose loading in all participants, reflecting generalized insulin resistance, but showed limited ability to discriminate between complication phenotypes. Conclusions: In people living with obesity without T2DM, elevated 1 h post-load plasma glucose during OGTT is consistently associated with multisystem obesity-related complications. These findings support the clinical relevance of 1 h post-load glucose as an integrated marker of early metabolic and systemic burden that may inform complication-driven risk stratification in obesity. Due to the observational study design, causality cannot be inferred.