What is Diabetic Nephropathy?

Diabetic nephropathy is also known as Kimmelstiel-Wilson syndrome, or nodular Diabetic glomerulosclerosis and intercapillary glomerulonephritis. It is a progressive kidney disease caused by angiopathy of capillaries in the kidney glomeruli. The disease is characterized by nephrotic syndrome and diffuse glomerulosclerosis. This is because of the longstanding diabetes mellitus, and is the major indication for dialysis.

When diagnosed with chronic kidney disease you will have to undergo treatment for long periods, and it is important that you choose the right nephrologist, because your nephrologist and you will form a team to take good care of your health.

Facts Explained

Diabetic nephropathy is the most common cause of renal failure, accounting for more than half of all cases of end-stage renal disease in the United States. (End-stage renal disease is disease that requires renal replacement with either dialysis treatment or a kidney transplant. Renal disease will affect between 20-40% of diabetics in their lifetime. Diabetic nephropathy involves steadily increasing proteinuria, accompanied by elevated blood pressure, with a progressive decline in GFR. There is also a greatly increased risk of cardiovascular disease.
Proteinuria is both a consequence of the glomerular damage in diabetes mellitus, and a cause of further damage, since it leads to inflammation and fibrosis in the renal tubules and a loss of functional nephrons. A specific assay for the small blood protein albumin is a more sensitive test to determine proteinuria than is a typical urine dipstick test for protein. If high values are measured, this is termed albuminuria. The table below gives values that are used to define moderately increased albuminuria (a precursor to diabetic nephropathy) and established disease. As with many physiological variables (e.g. blood pressure, hyperglycemia), cut-off values are used for definitions, however, the reality is that proteinuria is a continuous variable, and the risk of renal damage increases with the degree of proteinuria, no matter the amount.

Diabetic nephropathy causes characteristic changes to the structure of the glomerulus known as glomerulosclerosis. In glomerulosclerosis, there are increased extracellular deposits inside the renal corpuscle, with a decreased surface area available for filtration. The glomerular basement membrane becomes thicker, yet more leaky. Historically, these changes had been attributed to effects on endothelial cells and mesangial cells, the cells that support the capillary loops. However, more recent research suggests that effects on podocytes may be the most important factor in causing diabetic glomerulosclerosis.

Diabetic nephropathy can cause a disruption of the podocyte cytoskeleton, which results in a change in shape known as podocyte effacement. As well, diabetic nephropathy may cause the loss of podocytes. The most important consequence of these changes in the glomerulus is that they cause a leaky filtration membrane, so there is abnormally increased filtration of protein. Proteinuria then causes damage to the renal tubules and further loss of nephrons.