Are your kidneys in good shape? Is your filter breaking down due to diabetes? Dr Nicolin Datz, the new author in this series explains how one can answer these questions with just a simple urine test and protect the kidneys.

“Why did I have to give a urine sample to the lab today? What exactly do you do with it?”

“We have to examine your kidney function.”

“What has this got to do with my diabetes?”

Such a dialogue could easily have been taken from one of our consultations.
Twice a year, we require a urine sample from our patients. Only a few really know why they have to do this, or for what the urine is being tested.

In actual fact, the examination is to do with the kidneys. As a result of high blood sugar, deposits can be formed on the walls of the blood vessels – including those of the kidneys.

Diabetes can damage blood vessels
Diabetes is a chronic condition in which a lack of insulin causes high blood sugar levels. In order to normalize the blood sugar, insulin is injected or delivered via a pump. However, despite the highest degree of care, blood sugar levels can still swing radically. This can often be seen in children, whose bodily development is not yet complete. This is why phases of high and low blood sugar are not always avoidable.

Diabetes causes complications, but this doesn’t necessarily have to be the case. If, for example, high blood sugar remains constant over a long period of time, underlying complications are more likely to develop.

Diabetic angiopathy is the term we give to complications that involve damage to the large and small blood vessels. We make a difference between diabetic ‘macro’ angiopathy and ‘micro’ angiopathy: diabetic macroangiopathy referring to damage of the large vessels (=atherosclerosis); and diabetic microangiopathy referring to damage in the small vessels including the tiny arteries (capillaries).

What causes the damage?
Diabetic angiopathy is caused by long-term high blood sugar. High blood sugar concentrations in the small blood vessels can lead to metabolic disorders, leading to an increased permeability of the blood vessels and to a thickening of the membranes. Eventually, the blood supply to the organs becomes less efficient.

This is especially true for the eyes, the kidneys and the nerves, as the blood vessels in these organs are particularly small. We refer to these conditions as retinopathy (damage to the retina of the eye), diabetic nephropathy (damage to the kidneys) and diabetic neuropathy (damage to the nerves).

It is important to mention that these types of conditions do not appear with short-term jumps in blood sugar, but after years of poor blood sugar control. The first signs of damage may not even start to appear until after 10 to 15 years of diabetes duration.

The higher the HbA1c value, the higher the likelihood of developing such complications. If metabolic control remains good, it is indeed possible to prevent these complications from developing.
 
How kidneys work
Kidneys actually function like a filter: they filter from the blood superfluous matter that our bodies do not need, and produce the urine through which this waste (such as urea, uric acid and creatinine) is excreted. Essential elements, such as protein, are not excreted.

The filter consists of tiny blood vessels that, if the blood sugar levels remain high over long periods of time, are afflicted. The kidneys can no longer function optimally and the elements essential to the body are able to seep through, such as protein, which is subsequently excreted via the urine.
 
Microalbuminuria
Nephropathy begins with a slightly raised protein excretion rate. It is so small that it cannot be detected on a conventional test strip. This is why the urine has to be examined in the laboratory. If protein is then detected, it is referred to as microalbuminuria.  

Temporary microalbuminuria
Should microalbuminuria be determined, this could indicate the presence of kidney damage (nephropathy). However, raised protein levels in the urine can also be caused by other reasons, such as physical exertion or exhaustion, bladder infection, high blood pressure, and other acute infections.

In addition, raised albumin excretion can occur in children and adolescents, especially during puberty. This is only temporary, and later disappears. This form of microalbuminuria cannot be explained and is presumed harmless.

Chronic microalbuminuria
There is a considerable difference between chronic and temporary microalbuminuria. Chronic microalbuminuria indicates the presence of diabetic nephropathy. In order to hinder its further development, blood pressure and blood sugar must be brought under control.

Can I detect nephropathy myself?
No. The presence of early nephropathy can only be detected in a laboratory test. Visible symptoms do not set in at this stage. In order to detect nephropathy early, a urine sample should be taken once or twice annually.

How common is diabetic nephropathy?
Studies have shown that, after 30 years of diabetes duration, approximately 30–35% of patients develop nephropathy. Diabetes therapy has improved so much in recent years, however, that this figure is likely to drop in the future.

One thing is certain: Good metabolic control reduces the risk of developing diabetic nephropathy; and only through prevention and regular screening is early detection possible.