Abstract Context Physiologic changes in glucose metabolism are well-described to occur during puberty. However, there are important gaps in understanding the interaction between obesity and the normal physiologic changes during puberty, as well as how these changes could contribute to the increased risk of comorbidities, such as type 2 diabetes and dyslipidemia, in youth with obesity. Objective The objective of this study was to compare longitudinal changes in insulin sensitivity (Si) and secretion during pubertal progression in youth with obesity versus those with normal weight. Design Longitudinal observational study evaluating youth from early puberty (Tanner [T]2-T3) until puberty completion (T5). Setting Pediatric academic hospital Clinical Translational Research Center. Participants Pubertal youth with normal weight (n = 47; 22 female, 25 male) and obesity (n = 37; 23 female, 14 male) Main Outcome Measures Si, insulin response (acute insulin response to glucose, AIRg) and disposition index (DI) by intravenous glucose tolerance test at baseline (T2-T3), T4, and T5 Results Youth with obesity had significantly lower Si and higher AIRg at each time point (P < 0.001), but DI was similar between the groups. There were no group differences in trajectory of Si, AIRg or DI over time. Leptin, insulin-like growth factor-1, and obesity were most strongly associated with Si and AIRg at all time points. Conclusions Obesity significantly impacts Si during puberty, even at the earliest stages. However, in general, obese youth have adequate β-cell compensation for the significantly reduced Si of puberty. Future studies are needed to better predict the subset of youth who fail to maintain β-cell compensation during puberty.