Diabetic Kidney Disease: Chronic Kidney Disease and Diabetes

Abstract

The traditional clinical hallmark of chronic kidney disease (CKD) in diabetic microvascular disease of the kidney has been overt proteinuria; once manifest, diabetic nephropathy was considered apparent. The term “nephropathy” classically was associated with foamy urine, hypertension, and renal edema formation attributable to sodium retention and fostered by impaired kidney function and hyperglycemia. In fact, the simultaneous diagnosis of the triad of proteinuria, high blood pressure, and edema actually indicated that “the horse was out of the barn”; diabetic kidney disease was already present and likely had been for years. To emphasize the impact of diabetes on the renal parenchyma at much earlier stages of the disease, the National Kidney Foundation's Kidney Dialysis Outcomes Quality Initiative Clinical Practice Guidelines and Clinical Practice Recommendations for Diabetes and Chronic Kidney Disease now promote the term “diabetic kidney disease” (DKD) as a nonproteinuric designation of CKD in type 1 or type 2 diabetes.1 DKD will occur in 30–40% of people with diabetes, and one-third of these individuals may develop kidney failure. DKD occurs in patients with either type 1 or type 2 diabetes; however, patients with type 2 diabetes often present with a mixed picture of atherosclerotic renal changes coincident with diabetic histological findings. Judgment of whether hypertension or diabetes is the dominant lesion, in the absence of a kidney biopsy, is typically predicated on whether a renal ultrasonogram depicts small or normal-to-large kidneys. In the former instance, hypertensive angiosclerosis is considered causative, whereas the latter circumstance coincides with DKD, irrespective of the level of proteinuria. Importantly, when microalbuminuria, macroalbuminuria, or intermediate levels of protein excretion are detectable, the glomerular filtration rate (GFR) has usually passed through the stage of hyperfiltration. Thus, DKD is already present at a normal or slightly less-than-normal GFR. Principally, kidney function is declining with the GFR. At …