Description

Puberty is a complex process of physiological changes, including neuroreproductive and growth hormone activation and rapid organ growth, that may predispose organs to injury. The kidneys may be especially susceptible because they are highly metabolically active and second only to the heart with respect to oxygen consumption per tissue mass. During puberty, the kidneys almost double in size, likely increasing the kidneys' already high energy expenditure. In parallel, puberty is associated with physiologic insulin resistance (IR), which is accentuated in obesity. Our central hypothesis is that obese youth with prediabetes and T2D experience relative kidney hypoxia during puberty due to a metabolic mismatch between increased energy expenditure and impaired substrate metabolism. In turn, the kidney hypoxia results in loss of glomerular charge and size selectivity leading to increased transglomerular transport of protein and kidney dysfunction. Our preliminary data showed that pubertal adolescents with obesity and/or diabetes exhibit relative kidney hypoxia compared to normal weight controls using functional magnetic resonance imaging (MRI) and that relative kidney hypoxia is greater in late vs. early puberty. However, determining the pubertal mechanisms contributing to kidney injury in youth with obesity and T2D requires serial evaluations throughout puberty. To assess the impact of pubertal changes within a 5-year study period, the investigators propose an accelerated longitudinal study design in which the investigators will enroll adolescents (8-14 years, 50% girls) with obesity and/or elevated hemoglobin A1c (HbA1c ≥6%) [n=60], and healthy normoglycemic controls [n=40] at Tanner (pubertal) stages 1-4 and examine them at baseline, 1 and 2-years. The investigators will then compare data by Tanner stage to construct an integrated portrayal of the physiological changes that occur throughout puberty. Given the rarity of T2D prior to pubertal onset, the investigators chose to enroll a high high-risk group: youth with obesity and/or HbA1c ≥6.0% to represent youth ranging from those at magnified risk of developing T2D to those recently diagnosed.