REN and type 1 diabetes mellitus: Exacerbation of diabetic kidney disease by manipulations of the renin-angiotensin system such as renin overexpression [8], knockout of the bradykinin B2 receptor [7], or decorin deficiency [9] that have been studied so far in models of type 1 diabetes will not be discussed here, but the approaches are likely to be useful for type 2 diabetes as well.