In type 1 diabetes (T1D), adjuvant treatment with inhibitors of the renin-angiotensin-aldosterone system (RAAS), which dilate the efferent arteriole, is associated with prevention of progressive albuminuria and renal dysfunction. Uncertainty still exists as to why some individuals with long-standing T1D develop diabetic kidney disease (DKD) while others do not (DKD resistors). We hypothesized that those with DKD would be distinguished from DKD resistors by the presence of RAAS activation.