World Diabetes Day: November 14: Save your kidneys
Experts offer advice on how to manage the disease foot care, the diet, renal disease management and during pregnancy.
WORLD DIABETES DAY is observed annually on November 14 to commemorate the birthday of Frederick Banting who, along with Charles Best, discovered insulin in 1921. Across 130 countries and co-sponsored by the International Diabetes Federation (IDF) and the World Health Organisation (WHO), the day was first observed in 1991 in response to concern over the escalating incidence of diabetes around the world. Since 2001, the day, organised by the IDF member associations, has laid emphasis on diabetes-related complications and has a unifying theme. This year's theme is "Diabetes and Kidney disease", and the campaign title is "Diabetes could cost you your kidneys: Act now!"
Diabetic nephropathy (DN) is one of the chronic vascular complications of diabetes, which tends to develop after several years of diabetes and results in progressive loss of kidney function. DN is a leading cause of end-stage renal disease (ESRD) accounting for nearly one-third to one half of all cases of kidney failure. The frequency of ESRD is nearly 30 per cent in Type 1 (insulin dependent) diabetic individuals and ranges from four to 20 per cent in Type 2 (non-insulin dependent) diabetic individuals. In India, diabetes already accounts for more than 25 per cent of all cases of kidney failure. Diabetic individuals with kidney complications also face an increased risk of death from cardiovascular disease.
Stages of diabetic nephropathy
Diabetic nephropathy usually progresses through several stages. In stage 1, there is hyperfiltration of urine, but no leakage of albumin or protein. In stage 2, leakage of tiny amounts of protein or albumin is present. This stage is called stage of microalbuminuria. In stage 3 or the macroproteinuria stage, increasing proteinuria leading to loss of large amounts of protein, causing "nephritic syndrome" a condition defined by fluid retention and swelling due to low amounts of protein in the blood is observed. In stage 4, the kidneys become less able to remove "poisons" from the blood resulting in a build-up in the levels of various chemicals such as urea and creatinine. This is known as "chronic renal failure". Stage 5 is known as `End Stage Renal Disease' (ESRD). Here, urine output decreases, serum creatinine levels go very high and there is an imminent need for renal replacement therapy (RRT).
Microalbuminuria in the range of 30-299 mg/24-hour has been shown to be the earliest detectable and treatable stage of diabetic nephropathy and is also a significant marker for cardiovascular diseases in both diabetic and non-diabetic subjects. Patients with microalbuminuria are more likely to progress to clinical albuminuria (greater than or equal to 300 mg/24 h) and decreasing GFR over a period of years. Once macroproteinuria occurs, the risk for ESRD is high. In parallel with these changes, there is a rise in blood pressure, which may even begin before the development of microalbuminuria but usually occurs during the early microalbuminuric phase.
Luckily, not everyone with "long standing diabetes" develops nephropathy. In fact, over 50 per cent of diabetic patients will never develop kidney disease even if their blood sugars are poorly controlled. The risk factors for diabetic nephropathy are shown in the table (see below). It was reported in the United Kingdom that South Asians are more prone to diabetic nephropathy. However, our studies as well as those by others have not confirmed this in India. In one study we found that age, diastolic and systolic blood pressure, glycosylated haemoglobin, fasting plasma glucose, and duration of diabetes were the risk factors associated with diabetic kidney disease.
During the early stages of diabetes nephropathy, there are usually no symptoms. As the condition progresses, individuals with diabetic nephropathy may show swelling (edema) of the feet and legs. Later throughout the body, increase in blood pressure, larger amounts of protein leaking into the urine (macroproteinuria) and elevated levels of fats (cholesterol and triglyceride) occur in the blood. Once the kidneys are more severely damaged, blood sugar levels may drop because the kidneys retain insulin in the body and a stage of "burnt out diabetes" may occur. In late stages, patients become severely anaemic, breathless and serum potassium levels may arise, necessitating urgent dialysis.
Screening for nephropathy at its earlier stage of microalbuminuria, is important because it is reversible at this stage. Type 2 diabetic individuals should be screened at the time of diagnosis and every year, thereafter, even if a test is normal. If microalbuminuria or later stages of nephropathy are present, the test should be repeated bimonthly in order to classify the level of albumin in the urine. Frequent measurements are recommended as albumin levels vary up to 40 per cent from one day to another.
In Type 1 diabetic patients, microalbuminuria is rarely seen within the first five years after diagnosis of diabetes. Thereafter, it is recommended to screen for microalbuminuria on a yearly basis, starting with at least five years after diabetes is diagnosed.
Management and prevention
Control of blood sugar is the most important factor in the prevention of nephropathy in both Type 1 and Type 2 diabetic individuals. Intensive management of blood sugar to achieve near-normal levels significantly reduces the progression of diabetic nephropathy.
In general, people with diabetes should aim for blood pressure 130/80 mmHg and if persistent proteinuria is present, then a more stringent target of 120/75 mmHg is recommended. In patients with underlying nephropathy, angiotensin-converting enzyme (ACE) or angiotensin receptor blocker (ARB) therapy is also indicated as part of initial management.
With the onset of overt nephropathy, dietary protein is to be restricted to 0.8 g of protein/kg body wt/day (less than 10 per cent of daily calories). Further restriction may be useful in slowing the decline of GFR in selected patients. However, nutrition recommendations for patients with renal insufficiency require an individualised approach.
Prevention of renal failure allows patients to maintain a superior quality of life and reduce economic burden on the society and the individual.
Steps to reduce the risk and/or slow progression
Monitoring/screening for microalbuminuria
Optimise glucose control
Optimise blood pressure control
Angiotension converting enzyme therapy
Controlling blood lipids and cholesterol
Cessation of smoking
End stage renal disease (ESRD)
When end stage kidney failure is reached, dialysis and transplantation are the only options. Early detection and treatment can slow the rate of kidney damage and significantly lengthen the time required to reach the stage of dialysis or renal transplantation. As recently as the 1970s, medical experts commonly excluded people with diabetes from dialysis and transplantation programmes, in part because they felt damage caused by diabetes would offset the benefits of the methods of treatment. Today, because of better control of diabetes and improved rates of survival following treatment, physicians do not hesitate to offer dialysis and transplantation to people with diabetes. Indeed nearly half of all patients in these programmes are diabetic patients.
Three treatment modalities are available for renal replacement therapy: (i) hemodialysis, (ii) Continuous ambulatory peritoneal dialysis (CAPD) and (iii) transplantation (kidney transplantation or a combined pancreas and kidney transplantation). Each technique has its own advantages and disadvantages and the kidney specialist is the best person to decide on the option for a given individual.
Prevention is the best way to avoid lasting kidney damage from diabetic nephropathy. Once the condition is established, most people tend to progress slowly to chronic renal failure. By strict control of blood sugar and blood pressure, diabetic kidney disease can be prevented in most patients.
Good diabetes care makes a difference
If you have diabetes, act now to prevent nephropathy.
Measure your Haemoglobin A1C level at least twice a year.
Work with your physician regarding insulin injections, medicines, meal planning, exercise, and blood glucose monitoring to achieve tight diabetes control.
Check your blood pressure regularly at every visit and maintain BP less than 130/80 or 120/75 if there is proteinuria.
Ask your doctor whether you might benefit from receiving an ACE inhibitor
Yearly examination for microalbumin and protein in urine. If proteinuria is present, have your blood urea and serum creatinine estimated.
Ask your diabetologist/physician whether you should reduce the amount of protein in your diet.
Dr. V. MOHAN
Dr. R. GUHA PRADEEPA
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