Diabetes is the number one cause of chronic kidney (or renal) failure in the U.S., and kidney disease among people with diabetes has more than doubled in the past decade. According to the National Kidney Foundation, approximately 30% of people with long-term type 1 diabetes (about one in three) will develop kidney disease. The good news is that with early detection and proper treatment, kidney disease can be slowed and, in some cases, reversed.
Why Kidneys Are Crucial
The kidneys are the waste management system of the body, removing excess fluid and toxins from the blood stream and filtering them into the urine. The role they play is vital; if kidney function is significantly reduced and a patient develops end-stage renal disease (ESRD); the situation is life-threatening and a kidney transplant or regular dialysis treatments are the only treatment options.
One of the reasons people with diabetes are at a higher risk for kidney disease (also called nephropathy) is their increased incidence of high blood pressure. The stress of long-term hypertension can cause damage to the blood vessels of the nephrons, the functional filtering units of the kidney. Up to 65% of people with diabetes have high blood pressure; controlling it is essential to preventing diabetic kidney disease.
Signs and symptoms of kidney disease include:
- Frequent urination
- Blood and/or protein in the urine
- Burning during urination
- Puffiness and swelling (edema) in the face, hands, and feet
- High blood pressure
- Skin itching
- Nausea and vomiting
The American Diabetes Association recommends that urine tests for albumin (a type of protein) be administered to individuals with type 2 diabetes at the time of diagnosis and annually thereafter. Other measures of kidney function include blood tests for creatinine and blood urea nitrogen (BUN). Creatinine is a metabolic byproduct of creatine, the acid that supplies energy for muscle contractions, and BUN is an end-product of protein metabolism formed in the liver. Both urea and creatinine are filtered out of the bloodstream by the kidneys; high amounts of them in the bloodstream indicates renal impairment.
You may have reduced kidney function if:
- Microalbumin levels are greater than 30 mg in a 24-hour urine test
- Blood creatinine is greater than 1.2 (women) or 1.4 (men). (Note: this is a different test and measurement than urinary creatinine).
- BUN levels are greater than 8.
Ask your healthcare provider can help you interpret the lab test results.
Control Blood Pressure to Improve Kidney Health
The AACE and ADA set blood pressure guidelines for nonpregnant patients 18 years of age and older at less than 130 mmHg systolic and less than 80 mmHg diastolic.
Treatment strategies for diabetes-related hypertension include weight loss, smoking cessation, and dietary modifications (i.e., a low-sodium, low-cholesterol diet). If these lifestyle modifications fail to control blood pressure, medications such as statins, angiotension converting enzyme (ACE) inhibitors, and calcium channel blockers may be prescribed.
Control Blood Sugar Levels
Keeping blood glucose levels as close to normal as possible is one of the best weapons against diabetic kidney disease. The landmark Diabetes Control and Complications Trial found that patients with type 1 diabetes who maintained an average A1C of 7.2% reduced the risk of the development of nephropathy and other complications up to 75% — an effect that continued for at least eight years after the initial ten-year study concluded.
Some medical conditions, such as hypoglycemic unawareness, may make tight control of blood sugars unadvisable. Patients should always consult their healthcare provider and/or diabetes care team before attempting a tight control treatment regimen.
Keep an Eye on Dietary Protein
Overloading on dietary protein can speed the progression of kidney problems in people with existing kidney disease, so some physicians may recommend restricting levels as a precautionary measure. A registered dietitian experienced in diabetes and renal care can develop a meal plan that is low in dietary protein and compatible with blood sugar control goals.
It's not advisable to cut protein completely out of the picture. Insufficient dietary protein can cause nutritional deficiencies, and studies are still inconclusive on the benefits of protein reduction in lowering the risk of kidney disease in humans. The ADA currently recommends that most adults with diabetes who have no overt signs of kidney damage include the recommended daily allowance (RDA) of approximately 10% of total calories from protein in their diets. Consult with your diabetes care team before attempting a low-protein diet.
Nephrotoxic substances are those that have the potential to damage the kidneys. Advise your healthcare team of all prescription drugs, over-the-counter medications, and herbal remedies you are taking so they can monitor for the possibility of renal problems. Some potential hazards:
Analgesics. Potentially harmful in high doses or when taken over an extended period of time.
- Nonsteroidal anti-inflammatory drugs (NSAIDs). Can be toxic to patients who have reduced kidney function.
- Aminoglycoside antibiotics. Nephrotoxic to patients with kidney impairment.
- Contrast media. The injectable dye used in computerized tomography (CT scans) and some other radiographic tests. Other environmental agents, such as lead, pesticides, and solvents, can also cause kidney damage.