Type 2 diabetes (T2D) in youth is increasing in prevalence in parallel with the obesity epidemic. In the US, almost half of patients with renal failure have DKD, and ≥80% have T2D. Compared to adult-onset T2D, youth with T2D have a more aggressive phenotype with greater insulin resistance (IR), more rapid β-cell decline and higher prevalence of diabetic kidney disease (DKD), arguing for separate and dedicated studies in youth-onset T2D. Early DKD is characterized by changes in intrarenal hemodynamic function, including increased renal plasma flow (RPF) and glomerular pressure with resultant hyperfiltration, is common in Y-T2D, and predicts progressive DKD. Studies evaluating the two currently approved medications for treating T2D in youth (metformin and insulin) have shown these medications are not able to improve β-cell function over time in the youth. However, recent evidence suggests that bariatric surgery in adults is associated with improvements in diabetes outcomes, and even T2D remission in many patients. Limited data in youth also supports the benefits of bariatric surgery, regarding weight loss, glycemic control in T2D, and cardio-renal health. While weight loss is important, the acute effect of bariatric surgery on factors such as insulin resistance likely includes weight loss-independent mechanisms. A better understanding of the effects of bariatric surgery on pancreatic function, intrarenal hemodynamics, renal O2 and cardiovascular function in youth with obesity with or without diabetes is critical to help define mechanisms of surgical benefits, to help identify potential novel future non-surgical approaches to prevent pancreatic failure, DKD and cardiovascular disease. The investigators' overarching hypotheses are that: 1) Y-T2D is associated with IR, pancreatic dysfunction, intrarenal hemodynamic dysfunction, elevated renal O2 consumption and cardiovascular dysfunction which improve with bariatric surgery, 2) The early effect of bariatric surgery on intrarenal hemodynamics is mediated by improvement in IR and weight loss, 3) Some aspects of cardio-renal-metabolic complications of T2D are related to obesity and others to T2D independent of obesity. To address these hypotheses, the investigators will measure GFR, RPF, glomerular pressure and renal O2, in addition to aortic stiffness, β-cell function and insulin sensitivity in youth ages 12-21 with T2D (n=40) and in (n=up to 10) youth with similar BMI but without diabetes, before and after vertical sleeve gastrectomy (VSG). To further investigate the mechanisms of renal damage in youth with T2D, two optional procedures are included in the study prior to vertical sleeve gastrectomy: 1) kidney biopsy procedure and 2) induction of induced pluripotent stem cells (iPSCs) to assess morphometrics and genetic expression of renal tissue.
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Pancreatic β-cell function
Timeframe: 4 hours (MMTT)
Pancreatic β-cell function
Timeframe: 4 hours (hyperglycemic clamp)
Effective Renal Plasma Flow (ERPF)
Timeframe: 4 hours
Glomerular Filtration Rate (GFR)
Timeframe: 4 hours