The A1C Test and Patients with Chronic Kidney Disease

Disclaimer: This article is for informational purposes only and is not intended to be a substitute for medical advice or diagnosis from a physician.

In the United States, about 1 in 10 people have diabetes, a disease that affects the way the body produces or uses insulin. Insulin is a hormone that helps regulate glucose (sugar) in the blood.

When blood sugar levels get too high, health problems can develop, including kidney problems. In fact, about half of all people diagnosed with diabetes will develop kidney disease.

Persistently high sugar levels can damage the small blood vessels in the body. In the kidneys, diabetes can also cause damage to the tiny filters called glomeruli that filter the blood. The result is that your kidneys may begin to leak protein into the urine, and can become unable to properly eliminate the water, salt and waste products from your body.

Another complication of diabetes is nerve damage, often causing burning and numbness in the feet. However, it can sometimes also lead to trouble emptying the bladder. Pressure from a full bladder that doesn’t empty properly can further damage the kidneys.

What is the A1C test?

The A1C, or hemoglobin A1C test, is used to measure long-term blood glucose levels. It is typically given every three to six months to people with diabetes. This laboratory test shows the person’s average blood glucose control for the previous two to three months. It differs from the finger stick blood test that is used daily to monitor current blood sugar levels. For someone with diabetes, the goal is to have an A1C reading of less than 7.0 percent. For someone who is not diabetic, a normal A1C level is 4.0 percent to 5.9 percent.

Research has shown that when A1C levels are close to normal, the risk for complications of diabetes decreases. Even when A1C levels decrease by just one percentage point, the risk for complications, including kidney problems, eye disease, cardiovascular disease and nerve damage, decrease by an average of more than 50 percent.

If you have diabetes, your healthcare team may use the A1C test as a guide when prescribing diabetes medications, if needed. The A1C test is the most commonly used lab test for measuring long-term glucose levels.

Use of the A1C test in kidney patients

When people are diagnosed with both diabetes and chronic kidney disease (CKD), it becomes more difficult to rely upon A1C test results. Complications from kidney disease, including malnutrition and anemia, can affect the A1C result.

One study that tracked diabetes patients with end stage renal disease (ESRD) who were undergoing hemodialysis found that A1C tests underestimated blood glucose levels. Other studies have also shown that A1C tests may not be reliable when used on people with both diabetes and renal disease.

Scientists are currently examining other ways of evaluating blood glucose in patients with diabetes and ESRD. Some believe that tests measuring short-term blood glucose levels may work better for monitoring these patients. One such test measures glycated albumin, which is the amount of glucose that collects on albumin, the main protein found in blood plasma.

What should you do if your A1C level is high?

If your doctor does use the A1C test and your blood sugar levels are high, there are several things that can be done to lower it:

• Become physically active. Activity affects insulin and helps sugar move from your blood into your muscles, where it can be used for energy.
• Maintain a healthy weight. Body fat, especially around the midsection, is linked to insulin resistance. Less body fat will mean your body is likely to produce less insulin.
• Use carbohydrate counting to help manage how high your blood sugar rises after eating.
• If you are not able to achieve desired results through diet and exercise alone, your healthcare team may prescribe medication or make changes in your current medication plan.
• You may also be asked to monitor your blood sugars at home to keep track of how well you are doing.

Work with your dietitian to create a meal plan that supports good health. You may also want to consult a diabetes educator for tips on balancing your efforts to lose weight, increase exercise, follow your medication schedule and reduce stress.

A1C at a glance

The A1C is a test that monitors long-term blood sugar levels. In most people with diabetes, it is a good indicator of the risk from complications of diabetes. When people are diagnosed with both diabetes and chronic kidney disease, it becomes more difficult to rely upon A1C test results. If your A1C level is too high, exercise, diet and medication are all ways of bringing your level back into an acceptable range.