One complication of diabetes is diabetic nephropathy. A quick and simple way to check renal function is to draw a blood sample for serum creatinine and BUN tests. These tests should be performed when the patient is diagnosed with diabetes.Although the serum creatinine and BUN tests can quickly reveal the patient’s renal function, serum creatinine is the more sensitive indicator. Many extrarenal conditions, such as dehydration, can elevate the BUN level, but serum creatinine changes little except in renal disease. A normal serum creatinine level for an adult ranges between 0.7 and 1.5 mgjdl (0.6 and 1.2 mg/dl for adults over age 65). A normal BUN level for an adult ranges between 4 and 22 mg/dl (8 and 18 mgjdl for adults over age 65). Elevations in your patient’s serum creatinine and BUN levels require further testing before a physician can make a diagnosis of diabetic nephropathy

Nursing Considerations

Test results are more accurate if your patient fasts for 8 hours beforehand; therefore, try to schedule the test for first thing in the morning, so that most of the fasting time will occur while she is sleeping. Tell her not to eat breakfast.

If your patient is taking ascorbic acid, a barbiturate, or a diuretic, her physician will probably withhold it until after the test because these drugs can raise serum creatinine levels. Note whether your patient is receiving amphotericin B, an aminoglycoside, methicillin, or chloramphenicol. Any of these nephrotoxic drugs could be the source of her renal impairment.

After drawing the blood, send the sample to the laboratory immediately. To prevent hemolysis, which can alter the test results, handle the blood sample gently.

If the BUN level is elevated but the serum creatinine level isn’t, consider possible extrarenal causes before repeating the tests. Also, keep in mind that the amount of creatinine produced in the body is related to muscle mass. Therefore, an athlete with normal renal function may have elevated levels of serum creatinine.

If your patient’s serum creatinine and BUN levels are both high, check them frequently to monitor her renal function. Abnormal renal function coupled with diabetes places your patient at increased risk for endstage renal disease and cardiovascular disease. The frequency of these tests depends on how high the patient’s serum creatinine and BUN levels are and whether she exhibits other signs.

Blood Tests

Blood tests used to diagnose diabetes include the fasting blood glucose test, the 2-hour oral glucose tolerance test, and the random blood glucose test.

The glycosylated hemoglobin test is used to monitor the effectiveness of a patient’s therapy.

Blood tests used to detect and monitor the progression of diabetic complications include a fasting lipid profile for cardiovascular disease and serum creatinine and blood urea nitrogen (BUN) tests for renal disease.

Diagnostic Tests

A physician may order diagnostic tests to diagnose diabetes, detect diabetic complications, or monitor the effectiveness of a patient’s therapy. Of course, a patient should also perform self-monitoring to check the effectiveness of her therapy.

Early detection of diabetic complications allows for early treatment, which can minimize their destructive effects. Tests that help diagnose a complication can be repeated to monitor its progress

Peripheral neuropathy, a common complication of diabetes, causes sensory loss in the arms and legs. Such sensory loss in the feet increases the patient’s risk of developing foot ulcers that could ultimately lead to amputation.Usually, sensory loss is diagnosed by an examiner touching different areas of the patient’s foot with a pin. Unfortunately, this technique isn’t reliable. An examiner may not exert the same amount of pressure on each area, and some examiners are more heavy-handed than others. In fact, the same examiner may be heavy-handed one day and have a lighter touch the next, making comparisons difficult.

Filament testing with a monofilament device alleviates these problems. The device places exactly 10 grams of force on a small area of the skin . To assess sensory loss in the feet, an examiner uses the device at 10 sites on each foot.

The test result is normal if the patient feels the filament in all 10 spots on each foot. The result is abnormal if she doesn’t feel it in one or more spots.

Filament testing can be used to monitor the progression of a patient’s sensory loss and to help in tailoring an ulcer prevention program for her.

Nursing Considerations

Have the patient lie down on the examination table and instruct her to say yes each time she feels the filament.

Have her keep her eyes closed to avoid an invalid response. After the test, develop an ulcer prevention program for your patient .

This test places exercise demands on the heart and can uncover CAD not detected with an ECG. Many patients with diabetes have additional risk factors for CAD, such as obesity, hypertension, and abnormal blood lipid levels. Thus, a physician may have a patient undergo an exercise stress test even if her ECG is normal.

A stress test can also be used to monitor the progression of CAD. A patient may require periodic stress tests, especially if new symptoms of CAD appear or new risk factors are identified.

Nursing Considerations

Review your patient’s drug history and find out from her physician which drugs should be with­held and which she should take on the day of the stress test. A physician may withhold oral antidiabetic drugs because exercise lowers blood glucose levels. If your patient uses insulin, her physician may prescribe a lower dose to avoid hypoglycemia during the test.

Instruct your patient to rest the day before the test so that she has the energy to perform it. She should also fast for at least 3 hours and avoid smoking for at least 1 hour before the test. Explain to your patient what she can expect during the test and what she should wear. This information may ease her anxiety.

Determine if your patient has autonomic neuropathy, which affects involuntary functions, such as heart rate and blood pressure. During stress testing, patients with such neuropathy may not experience chest pain even though ischemia develops. Also, the blood pressure may go very high or very low when exercising. If your patient has autonomic neuropathy, closely monitor her throughout the test. The physician may even decide that an exercise stress test is inappropriate for such a patient and substitute a dipyridamole­thallium test. With this test, dipyridamole, instead of exercise, is used to put stress on the heart. The thallium acts as a contrast agent.

A fasting blood glucose test evaluates the patient’s ability to regulate glucose levels. A blood sample is taken by venipuncture after the patient has fasted for about 8 hours. Although values may vary slightly among laboratories, a finding between 70 and 120 mgjdl is considered normal in nonpregnant adults . A physician makes a diagnosis of diabetes if the finding is 126 mgjdl or more.A fasting blood glucose test can also be used to monitor the effectiveness of the patient’s treatment. If the glucose level is consistently elevated, the patient’s prescribed regimen may need to be changed. However, an elevated fasting blood glucose level in a patient with Type 1 diabetes doesn’t always signal a need for more insulin. If the patient has the Somogyi phenomenon, less insulin may be needed. This phenomenon results from insulin ­induced nocturnal hypoglycemia, which causes counter regulatory hormones to raise blood glucose levels through internal compensatory mechanisms. To alleviate the phenomenon, the physician will decrease the patient’s insulin dosage to eliminate nocturnal hypoglycemia.

Nursing Considerations

Before the test, tell your patient that she must fast for 8 hours. Make sure she understands that during the fast she may eat nothing and drink only water. Instruct her to fast for no more than 16 hours before the test. A fast of more than 16 hours or less than 8 hours can falsely increase glucose levels.

If the patient already uses insulin or an oral antidiabetic drug, her physician will withhold it during the fast. After the test, the patient can go back to her regular medication schedule. Instruct your patient to maintain a normal activity level during the fast. Any increase in activity can lower blood glucose levels and cause a false normal result.

If your patient is hospitalized before the test and her diabetic medication hasn’t been withheld during the fast, check her during the night for hypoglycemia. If she appears restless or diaphoretic while sleeping, wake her and check her blood glucose level. Nightmares and a headache in the morning also suggest nocturnal hypoglycemia. If you detect hypoglycemia, break the fast, appropriately treat the patient, and reschedule the test. If the patient isn’t hospitalized and her diabetic medication hasn’t been withheld, have a family member check her during the night.

If you draw the blood for a fasting blood glucose test to be performed at a laboratory, send the sample immediately. If the sample is left at room temperature, blood glucose levels will decrease. If you can’t send it right away, refrigerate it.

To monitor blood glucose levels at home, a patient can perform a fasting blood glucose test, using a fingers tick and a self-monitoring meter. Explain that if the test shows hyperglycemia, she should check the calibration of her meter. If it’s correct, she should repeat the test to verify her initial results. Reassure your patient that blood glucose levels fluctuate and an infrequent elevation in the fasting blood glucose level doesn’t indicate a loss of diabetic control. Elevated levels are significant only if they persist.