Diabetic nephropathy/Sclerosis

Alternative names:

diabetic glomerulosclerosis; diabetic kidney disease; Kimmelstiel-Wilson disease

Definition:

A kidney disorder that is a complication of diabetes mellitus, characterized by proteinuria and progressive reduction in kidney function.

Causes, incidence, and risk factors:

Uncontrolled diabetes causes damage to many tissues of the body. Kidney damage caused by diabetes most often involves thickening and hardening (sclerosis) of the internal kidney structures, particularly the glomerulus (kidney membrane). Kimmelstiel-Wilson disease is a form of diabetic nephropathy in which sclerosis of the glomeruli is accompanied by nodular deposits of hyaline (a type of connective tissue).

The glomeruli are the site where blood is filtered and urine is formed. They act as a selective membrane, allowing some substances to be excreted in the urine and other substances to remain in the body. As diabetic nephropathy progresses increasing numbers of glomeruli are destroyed, resulting in impaired kidney functioning. Filtration slows and protein (which is normally retained in the body) may leak in the urine. Protein may appear in the urine for 5 to 10 years before other symptoms develop. Hypertension often accompanies diabetic nephropathy.

Diabetic nephropathy eventually causes nephrotic syndrome (a group of symptoms characterized by excessive loss of protein in the urine) and chronic renal failure. The disorder continues to progress, with end-stage renal disease developing within 2 to 6 years after the appearance of chronic renal failure or significant hypertension.

The mechanism that causes diabetic nephropathy is unknown. It may be caused by inappropriate incorporation of glucose molecules into the structures of the basement membrane and the tissues of the glomerulus.

The disorder affects about 4 out of 10,000 persons. About 40% of people with insulin-dependent diabetes will eventually develop end-stage renal disease. 80% of people with diabetic nephropathy as a result of IDDM have had this diabetes for 18 or more years. At least 20% of people with NIDDM will develop diabetic nephropathy, but the time course of development of the disorder is much more variable than in IDDM. The risk is related to the control of the blood-glucose levels. Risk is higher if glucose is poorly controlled than if the glucose level is well controlled.

Diabetic nephropathy is generally accompanied by other diabetic complications including hypertension, retinopathy, and vascular (blood vessel) changes, although these may not be obvious during the early stages of nephropathy. Nephropathy may be present for many years before nephrotic syndrome or chronic renal failure develops. Nephropathy is often diagnosed when routine urinalysis shows protein in the urine, indicating renal dysfunction.