Kidney Disease and Diabetes
Kidney Disease and Diabetes
One of the long-term complications of diabetes can be kidney disease and most of us are aware that prevention of the development of kidney disease is one of the reasons we need to keep good blood glucose control. Aggressive treatment of blood pressure and stopping smoking, are also methods by which kidney disease can be either prevented or treated.
- Diabetes is the single most common cause of end-stage renal disease [ESRD] in Europe and the US.
- Between 30 and 50 % of people with diabetes are at risk of kidney disease.
- People with Type 2 diabetes often have microalbuminuria and overt nephropathy shortly after the diagnosis of their diabetes, because diabetes is often present many years before diagnosis.
- The key to preventing kidney damage is early detection of the excretion of protein in the urine and early intervention with treatment.
- People with kidney disease are at higher risk of heart disease. Therefore attention should be given to lowering blood pressure and cholesterol, taking exercise and not smoking.
Definition of kidney disease or nephropathy [its medical name]
Diabetes at Your Fingertips, a very useful book, defines it as:
“In the first instance nephropathy makes the kidney more leaky so that protein [albumin] appears in the urine. At a later stage it may affect the function of the kidney and in severe cases leads to kidney failure.”
What are the ways in which diabetes can affect the kidneys?
- If there is a lot of sugar in the urine, because you are running high for whatever reason, then this can lead to infection that can spread from the bladder to the kidneys. Chronic kidney infections do not always produce symptoms and may only show up on routine clinic tests.
- In both longstanding and poorly controlled diabetes the kidneys have to work hard to get rid of the excess sugar and the small blood vessels in the kidneys can be damaged, in a similar way as the small vessels in the eyes which causes retinopathy. It is logical therefore that if both diabetes and high blood pressure are present the risk to the kidneys is greater.
Does kidney damage produce symptoms?
- In the early stages there are no symptoms and any kidney damage should be picked up in the urine tests carried out at your normal clinic visit when albumin levels are measured.
- If large amounts of urine are lost then this leads to frothing of the urine and a build up of fluid in the body with swelling of the ankles [oedema] but this should be spotted in the routine clinic urine tests.
What is microalbuminuria?
This is the name for the condition described above where abnormal amounts of protein [albumin] leak from the kidneys into the urine. It is the first sign kidney disease may be developing. If kidney damage progresses then there are increased amounts of protein excreted in the urine and this is called macroalbuminuria.
The presence of microalbuminuria is detected by testing all the urine collected during a 24hour period. The test carried out in the laboratory checks the ratio of albumin to creatinine, another substance which, if higher than normal, is a good predictor of kidney damage. Creatinine is a waste product produced as a result of muscle activity. The albumin/creatinine ratio is measured in micrograms per milligram, g/mg. People without diabetes normally excrete less than 25 g/mg per day although this ‘normal’ figure is less in men [18 g/mg] than in women [25 g/mg].
Understanding the results
From personal experience, when my daughter was given the results of her first 24 hour urine collection, we knew they were high but did not know how high. The actual figures were meaningless to us because we didn’t know the normal range and how high they can go. For example a figure of 29 sounds dreadful but not if you look at the worst possible figures! So that other people are able to understand their results and maybe not worry quite so much, with the permission of Diabetes Interview we are printing their table of ranges of albumin/creatinine ratios:
|Normal albuminuria||17g/mg or less|
|Low microalbuminuria||18-65 g/mg|
|High microalbuminuria||66-250 g/mg|
|Proteinuria||More than 250 g/mg|
|Normal albuminuria||25 g/mg or less|
|Low microalbuminuria||26-29 g/mg|
|High microalbuminuria||93-355 g/mg|
|Proteinuria||More than 355 g/mg|
Note: Don’t panic at one high result! Results of urine tests for protein can be high for various reasons – for example it could be due to an infection of the kidney, bladder and urethra or if you had been exercising vigorously around the time of the test. If subsequent tests are consistently higher than expected, then your doctor should carry out further tests and, if necessary, treatment.
Your doctor will decide when, and if, you should receive treatment for microalbuminuria. The key to preventing kidney damage is early detection of the excretion of protein in the urine and early treatment to slow down the progression of microalbuminuria to prevent further kidney damage. Microalbuminuria can progress to renal failure if left untreated.