The Effects of Bariatric Surgery on Kidney Oxygenation in Obese Adults With Type 2 Diabetes and Hyperfiltration

DKD (diabetic kidney disease) is the leading cause of chronic kidney disease (CKD) and leading to significant morbidity and early mortality. Although multiple mechanisms underlying DKD have been proposed, the exact underlying mechanisms remain uncertain resulting in limited treatment options. Accumulating evidence, derived from animal and human studies has indicated that chronic kidney hypoxia is a key underlying determinant of DKD and recent studies in T2D patients have related truncal obesity to glomerular hyperfiltration and unfavorable kidney hemodynamic function that may drive kidney hypoxia. Hyperfiltration is defined as increased whole-kidney GFR or as single-nephron hyperfiltration in people with GFR in the normal range. Hyperfiltration is an early recognized key factor driving kidney disease progression in people with diabetes as it drives subsequent eGFR loss. Increased and dysfunctional (i.e., altered adipose tissue biology) visceral adipose tissue (VAT) present in central obesity is thought to disturb the balance between kidney oxygen- consumption and delivery through secretion of endocrine signals resulting in induction of insulin resistance, mitochondrial dysfunction and impaired substrate metabolism amongst others. In line with this theory, reduction of abdominal obesity following bariatric surgery has demonstrated to improve kidney outcomes in some but not in all individuals. In part this may be sex-specific. Since women have a lower risk for progression of DKD, the role of kidney hypoxia in DKD need to be studied in this regard individualized for sex. In this study, the investigators will address the effects of bariatric surgery on changes in kidney oxygenation using a sex-specific approach in people with hyperfiltration.