KIDNEY AND DIABETES MELLITUS

Alternative names: diabetic nephropathy, diabetic renal disease

Diabetic nephropathy represents currently the main cause of terminal kidney failure. Amongst us, 25% of the patients on hemodialysis suffer from diabetic nephropathy. In addition to this elevated prevalence, nephropathy in diabetics is associated with a high frequency of death by other causes, mainly vascular ones.

In diabetes mellitus (DM), several complications occur in the target organs:
 

retinopathy in the eyes
hypertension, infarction and angina in the heart
obstructions of arteries of limbs in the vascular system
nephropathy in the kidney

What is it?

Diabetic nephropathy is a renal disease that occurs in diabetic patients. Around 35-45% of the patients with insulin-dependent diabetes mellitus and 20% of the non-insulin-dependent diabetics develop renal disease after more than 10 years of diabetes. Diabetic renal disease may develop slowly or rapidly, leading the patient to chronic kidney failure. The functional decline of the kidney in the diabetics owing to nephropathy is predictable and progressive. Once nephropathy is established, the monthly loss of renal function ranges from 0.5% to 1%. The renal lesion is characterized by affecting the renal filter (glomerular sclerosis) and hence a renal loss of proteins of varying degree takes place through urine (proteinuria). With the deterioration of the glomerular filtration comes renal failure, almost always accompanied by arterial hypertension.

How does it manifest itself?

The diabetic renal disease begins with chronically uncontrolled glycemia. Excessive hyperglycemia overcomes the kidney ability to save glucose, allowing it to be lost through urine (glycosuria). The increased effort due to excessive glycosuria makes the kidney become enlarged, this being the first alteration sign found in imaging exams. Even with suitable compensation of blood sugar, minimal lesions keep occurring in the kidney for a period of 2 to 3 years without clinical or laboratory manifestation.

The next phase of onset of diabetic nephropathy occurs by the appearance of proteins in the urine in the form of microalbuminuria. This period of small albumin loss through urine may last from 5 to 10 years. Over time, proteinuria increases a lot and kidney failure signs emerge with elevation of blood urea and creatinine. Thus, the already established chronic renal disease advances irreversibly to ultimate kidney failure.

In short, hyperglycemic patients present with a great urinary volume (polyuria) and hyperglycosuria. This situation highly increases the kidney effort and entails, consequently, its enlargement. That´s why the diabetics´ kidneys are large. In routine laboratory tests with diabetics, protein loss is always investigated. When microalbuminuria appears, glomerular sclerosis lesions also appear, becoming scattered over time and increasing albumin loss through urine.

How is it diagnosed?

Diabetics can be insulin-dependent or non-insulin-dependent. Both types must undergo frequent urine tests for detection of microalbuminuria, which is an early indicator for diabetic nephropathy. Thus, protein loss through urine is fundamental to diagnose the diabetic´s renal disease. The presence of elevated urea or creatinine only occurs when the kidney has already lost more than 50% of its functional capacity. As the renal function declines, arterial hypertension, edema, hematuria and urinary infection may appear.

How to treat it?

The adequate management of diabetic nephropathy depends on the stage in which it is found. The doctor evaluates each case and determines the necessary treatment, which always includes:
 

strict control of blood sugar with use of insulin or specific drugs;
maintenance of arterial pressure as normal as possible;
suitable diet concerning especially sugars, proteins and sodium (salt);
and use of inhibitors of the angiotensin-converting enzyme in order to keep arterial pressure levels normal;

The goal of the treatment for diabetic nephropathy consists of prevention or reduction in the speed of progression to chronic renal failure, which, once established, allows two treatment options only;
 

dialysis
kidney transplant

The criteria for beginning dialysis are:
 

creatinine levels above 6mg%;
urea above 150 mg%;
nausea and vomiting;
itching;
urinous breath and great decrease in diuresis;
weakness and intense anemia.

Thereby, the patient is prevented from reaching an advanced degree of uremia with uremic encephalopathy and pericarditis.

How to prevent it?

The onset of renal disease in the diabetic depends to a great extent on the management of glycemia.

It usually takes years for the disease to establish, but this happens faster if some measures aren´t taken, namely:
 

efficient and permanent control of blood glucose;
maintenance of tensional levels near normal, with use of blockers of angiotensin-converting enzyme I
diets free of protein excess.

The pathogenesis of diabetic nephropathy is complex, involving a number of factors that interact with metabolic disorders and genetic factors. Several biochemical and cell alterations are involved in this disease. Thus far, some elements of the pathogeny keep on being discussed.

Questions you can ask your doctor about:

Is my kidney affected because I´m diabetic?

How can I find if my kidney is being damaged?

Can diabetics undergo transplantation?

In addition to my kidney, can other organs be affected?

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