Diabetic Kidney Disease is the single largest cause of kidney failure in the U.S., accounting for approximately 40% of all cases. These patients then require chronic dialysis or a kidney transplant to stay alive. It’s estimated that kidney failure requiring dialysis will develop in 20% to 40% of Type 2 diabetics who have diabetes for more than ten years. By the year 2020, it’s estimated that 80% of dialysis patients will be Type 2 diabetics.

Diabetes, along with high blood pressure, affects kidney function slowly over a period of years. You don’t develop symptoms due to diabetic kidney disease until it is too late and you’re about to go on dialysis. Remember, diabetes is a silent killer.

Misconceptions About Diabetic Kidney Disease

• Often people have the misconception that if you’re urinating fine, then your kidneys must be functioning normally. Wrong! You will continue to urinate without symptoms while diabetes and high blood pressure damage your kidneys. Pain, burning, or difficulty urinating are usually symptoms of urinary bladder infection or prostate enlargement, not kidney disease.

• People often mistakenly think that pain in the lumber region is due to kidney disease. Pain in the lumbar region is almost always due to diseases of the lumbar spine, such as a herniated disc, arthritis, or a muscle spasm. Only rarely are kidneys responsible for pain in the lumber region.

• Another misconception is that if your kidney ultrasound or CT scan is normal, then your kidneys must be normal, too. The fact is that these imaging tests focus on structural problems in the kidneys, such as stone formation, obstruction or tumors. Diabetes and high blood pressure, on the other hand, cause a chronic, slow decline in kidney function. Diabetic kidney disease is diagnosed by utilizing blood and urine tests.

Before I discuss how diabetes affects your kidneys, let me first briefly discuss the normal functions of the kidneys.

Normal Functions of The Kidneys

By far, the most important function of the kidneys is to form urine and thereby, remove waste products of cellular metabolism from the blood stream and deposit them into the urine. The basic functioning unit of the kidneys is called the nephron. The formation of urine takes place in the nephron as a result of filtration of water, electrolytes (such as sodium, potassium and calcium), and waste products of metabolism (such as creatinine from the muscles).

Clinically, the filtration rate of the kidneys is called GFR (Glomerular Filtration Rate). It is measured as creatinine clearance, a test that involves collecting urine for a twenty-four-hour period. Blood urea nitrogen (BUN) and serum creatinine are the typical tests for kidney function and are included in most blood chemistry panels. Serum creatinine is a more accurate test for kidney function than BUN. In the US, laboratories use serum creatinine and give an estimated GFR.

The Other Important Functions of the Kidneys:

• Regulation of electrolytes (such as potassium, sodium and calcium) in the blood

• Maintaining adequate hydration

• Regulation of blood pressure

• Regulation of Vitamin D metabolism

• Production of a hormone, erythropoietin, which is important for the normal production of red blood cells

Stages in the Development of Diabetic Kidney Disease

Diabetes affects kidneys slowly over a period of years and causes a progressive decrease in kidney functions. We divide this gradual decline in kidney functions into five stages.

Stage 1: Hyperfiltration

There is an increase in the filtration rate at the nephron level, which is the basic functioning unit of the kidney.

Normal creatinine clearance is 80–120 ml/minute. In the stage of hyperfiltration, the creatinine clearance rate may be as high as 170 ml/minute or more. In the blood chemistry panel, BUN and creatinine are normal at this stage. Patients do not have any symptoms at this stage of Diabetic Kidney Disease, which usually lasts several years.

Diabetic Kidney Disease is easily halted and even reversed at this point. Therefore, it is very important to diagnose kidney disease at this stage. This can easily be accomplished by measuring creatinine clearance, which requires a twenty-four-hour urine collection.

Stage 2: Microalbuminuria

At this stage, albumin, a special protein, starts to leak into the urine due to damage to the wall of the nephron. Clinically, this albumin leakage can be detected by measuring albumin excretion in the urine. A urinary albumin excretion of more than 30 mg but less than 300 mg in a twenty-four-hour period is known as microalbuminuria. In the blood chemistry panel, BUN and creatinine are usually normal at this stage.

As with Stage 1 Diabetic Kidney Disease, patients do not have any symptoms of Diabetic Kidney Disease at this stage, which usually lasts for several years. Routine urine testing does not detect this small amount of albumin excretion. Instead, three special methods of screening for microalbumin excretion are available:

• Measurement of albumin-to-creatinine ratio in a random urine sample
• Timed (four hours or overnight) urine collection
• Twenty-four-hour urine collection

Diabetic Kidney Disease at this stage can be halted and even reversed in a majority of patients.

Stage 3: Frank Proteinuria

With further progression of Diabetic Kidney Disease, larger quantities of albumin start to spill into the urine. If a twenty-four hour urine albumin excretion exceeds 300 mg in twenty-four hours, it is called Frank Proteinuria. In the blood chemistry panel, BUN and creatinine may be abnormal at this stage. This stage of Diabetic Kidney Disease may last a few years.

Patients in this stage may start experiencing some ankle swelling. Many patients, however, do not experience any symptoms at this stage.

Stage 4: Nephrotic Syndrome

With further progression of Diabetic Kidney Disease, urinary protein excretion may reach several thousand milligrams per day. A proteinuria of more than 3000 mg in twenty-four hours is known as Nephrotic Range Proteinuria. In the blood chemistry panel, BUN and creatinine are usually abnormal at this stage.

Often patients have high blood pressure as well. Patients with Nephrotic Syndrome usually have symptoms of leg swelling, abdominal swelling, and even shortness of breath due to the accumulation of fluid inside the chest cavity.

Stage 5: End Stage Renal Disease

In this stage, patients have many symptoms such as fatigue, leg swelling, poor appetite, intractable itching, and mental confusion.  In the blood chemistry panel, BUN and creatinine are always abnormal at this stage. Patients also have high blood pressure, which is usually difficult to treat.

These patients are treated with chronic dialysis, usually three times a week. They are prone to all sorts of complications, such as infections and clotting of the dialysis access, low blood counts, high risk for bleeding, Vitamin D deficiency, Parathyroid Disease, and Osteoporosis. These patients are also at a very high risk for heart attacks, strokes, and leg amputations. They are usually frequent visitors to the hospital. Quality of life is often poor at this stage.

How to Prevent Diabetic Kidney Disease

Fortunately, Diabetic Kidney Disease can be prevented, but only with early diagnosis and aggressive treatment of Diabetes and high blood pressure. Unfortunately, Diabetes and hypertension remain un-diagnosed and untreated in millions of people worldwide.

By the time Diabetes is diagnosed, a number of people have already developed Diabetic Kidney Disease. Several excellent clinical studies, including my own clinical experience, have demonstrated that aggressive control of blood glucose and high blood pressure can significantly reduce the risk for kidney disease.

By using the five-step treatment approach, I have been able to prevent end stage renal disease in the vast majority of my diabetic patients.

1. Good Control of Diabetes

Diabetic Kidney Disease primarily develops in those patients who have poor control of diabetes. Excellent control of Diabetes can prevent development of kidney disease. I set the following targets for controlling diabetes in my patients. 

Target Blood Glucose Values 

• Premeal blood glucose levels should be 90–120 mg/dl.
• Two-hour postmeal blood glucose levels should be less than 140 mg/dl
• Hemoglobin A1c (HbA1c) should be less than 6.0%

2. Good Control of Blood Pressure

Hypertension should be aggressively treated in diabetic patients. I aim for blood pressure to be less than 130/80 mm Hg in most of my diabetic patients. The selection of drugs to control blood pressure is important.

I use ACE (Angiotensin Converting Enzyme) inhibitors and/or ARB (Angiotensin Receptor Blocking) drugs as the first choice to treat high blood pressure in diabetic patients. Several excellent scientific studies have clearly demonstrated that the ACE inhibitors as well as ARBs not only control high blood pressure, but also preserve kidney function.

Other Drugs That can be Used to Treat Severe High Blood Pressure Include:

• Diuretics, in small doses (such as hydrochlorthiazide or indapamide)
• Calcium channel blockers (such as Norvasc, diltiazem, or verapamil)
• Alpha blockers (such as Cardura)
• Beta-blockers (such as carvedilol, atenolol or metoprolol)
• Centrally acting drugs such as clonidine

3. Urinary Microalbumin Excretion Test

This special urine test should be done on a yearly basis, especially if your Diabetes is not optimally controlled. A routine urine test does not check for it. As I mentioned earlier, there are three ways to carry out this test.

• Measurement of albumin-to-creatinine ratio in a random urine sample
• Timed (four hours or overnight) urine collection
• Twenty-four-hour urine collection

Diabetic patients who have microalbuminuria should be considered for an ACE inhibitor or an angiotensin receptor blocking (ARB) drug even if their blood pressure is not elevated, only if they don’t develop symptoms of low blood pressure.

A number of well-designed scientific studies have shown that ACE (Angiotensin Converting Enzyme) inhibitors as well as ARB (Angiotensin Receptor Blocking) drugs can reduce microalbuminuria and slow down the progression of diabetic kidney disease.

However, I must emphasize that an excellent control of diabetes is the most important factor to prevent as well as slow down chronic kidney disease in diabetics. The case of Susan (Case Study #5 from Chapter on Treatment of Diabetes) is a good example. She was on an ARB drug, Losartan, but she was still having marked albuminuria, as her Diabetes was uncontrolled. Once, her Diabetes got under better control, her albuminuria reduced markedly within a matter of few months.

ACE (Angiotensin Converting Enzyme) Inhibitors

ARB (Angiotensin Receptor Blocking) Drugs

For more details, please refer to my book, “Reverse Your Type 2 Diabetes Scientifically.”