Diabetic Nephropathy

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What is Diabetic Nephropathy?

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Diabetic Nephropathy is a common complication of diabetes mellitus in which there is long term damage to the kidneys as a result of long-term poorly controlled diabetes. The renal vessels and the glomerulus (filtering part of the kidney) are the main areas affected. Diabetic nephropathy is characterised by the presence of a protein called albumin in the urine, hypertension (high blood pressure), oedema (swelling), and progressive renal insufficiency.

Who gets Diabetic Nephropathy?

The incidence of Diabetes Mellitus (DM) in the Western World has increased dramatically over the past two decades. The prevalence of DM in the US rose from 8.9% in 1976 to 12.3% in 1994. This rate of increase is greater for type II than type I diabetes mellitus. Diabetic nephropathy affects 25-45% of patients diagnosed with DM under age of 30 years. It also less commonly occurs in those diagnosed at an older age.

Predisposing Factors

1. Diabetes Mellitus - Type I and type II 2. Uncontrolled diabetes - Increased rate of progression 3. Hypertension- Increased rate of progression 4. Smoking- Accelerates the deterioration in renal function

Progression

The natural history of this condition is quite predictable, more so in the case of type I diabetes mellitus. The first change is an increase in glomerular perfusion and renal hypertrophy that occur in the first two years of illness. Over this time glomerular filtration increases. Over the next three years, GBM thickening, glomerular hypertrophy and expansion of the mesangium will return this increase to normal. After 5-10 years of type I DM (more variable in type II) patients will begin to pass small amounts of protein (microalbuminuria) in the urine. Blood pressure may begin to rise at this point. Without intervention, the microalbuminuria will progress to gross amounts of protein in the urine (proteinuria). The natural history of type II DM differs from type I in three important ways: 1. Microalbuminuria (small but abnormal amounts of albumin ) or overt nephropathy (nerve breakdoown) may be present at diagnosis of type II DM reflected the long asymptomatic period common to patients with type II diabetes. 2. Hypertension more often co-exists with proteinuria in patients with type II DM. 3. Microalbuminuria is less predictive of deterioration to ESRD in type II diabetics.

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