The glycosylated hemoglobin test evaluates your patient’s response to diabetes therapy. The test measures the degree to which glucose attaches to hemoglobin (a process called glycosylation). Glycosylation occurs continually during the 120-day life of a red blood cell (RBC). The higher the blood glucose level, the greater the attachment. Once glucose attaches to hemoglobin, the process is nearly irreversible, which makes the glycosylated hemoglobin test an accurate reflection of your patient’s average blood glucose level during the 4 to 8 weeks before the test.The test values are given as a percentage of the total hemoglobin within an RBC. Three he­moglobins can be measured as Ala, Alb and Alc. The hemoglobin most commonly measured is Alc because it’s normally present in the largest quantity (3% to 6% of total hemoglobin). Ala is typically 1.6%, Alb is 0.8%. The closer to normal the patient can maintain her blood glucose level over an extended period, the closer to normal her glycosylated hemoglobin will be.

Nursing considerations

If your patient uses insulin, she should have a glycosylated hemoglobin test every 3 months. For patients who don’t use insulin, the frequency of the test depends on their response to therapy, which is determined by fasting blood glucose levels.

Your patient needs no preparation before the test. If you’re collecting the specimen, perform a venipuncture and collect the blood in a 5-ml lavender-top tube. Make sure the tube fills completely. Then gently invert it several times to mix the blood and anticoagulant adequately. If hemolysis occurs, collect a new specimen.

If the glycosylated hemoglobin value is elevated but the patient reports normal blood glucose levels from her self-monitoring tests, perform a second glycosylated hemoglobin test to rule out collection or laboratory error. If the second test is consistent with the first, evaluate the patient’s self-monitoring technique and correct any errors. If the patient’s technique is correct, the problem may be that she’s reporting normal values even though her tests reveal elevated glucose levels. Try to make your patient comfortable enough to express any problems she’s encountering in trying to comply with her treatment plan, and emphasize the importance of blood glucose control in delaying the development of long-term complications.

As with other chronic complications of diabetes, encourage your patient to modify risk factors associated with atherosclerosis, such as cigarette smoking and hypertension. And make sure that her plan of care includes exercise, diet, and, if necessary, drugs to control cholesterol levels.

Management of Foot Problems

Foot ulcers can lead to serious complications. If your patient has poor circulation, which impedes healing, she may develop ischemia or gangrene and may require amputation of her toes or foot. Meticulous foot care, along with tight blood glucose control and other measures, can help prevent these complications. In fact, up to 50% of amputations performed on patients with diabetes could be avoided with aggressive foot care.

If your patient has a foot ulcer and you suspect an infection, obtain a wound culture to check for bacteria. If she has an infection, the physician will prescribe an antibiotic. An infected wound may require incision, drainage, or debridement. If the physician suspects osteomyelitis, the patient will undergo tests, such as a nuclear bone scan.

Keep in mind that blood glucose levels usually climb in response to infection, increasing the patient’s insulin requirements. To promote wound healing, your patient should control her blood glucose levels to avoid hyperglycemia. If levels reach 200 mg/dl, macrophages and other white blood cells (WBCs) can’t fight the infection effectively. If your patient has an infected wound, be sure to monitor her for complications of severe hyperglycemia, such as DKA.

Drug Therapy

The physician may prescribe pentoxifylline to help ease your patient’s symptoms of intermittent claudication. This drug increases RBC flexibility and decreases blood viscosity, plasma fibrinogen, and platelet aggregation. This, in turn, improves blood flow and enhances tissue oxygenation. The physician may also prescribe platelet inhibitors, such as aspirin or ticlopidine, to help slow the progression of atherosclerosis.

Surgery

Several surgical options are available for treating peripheral vascular disease, including aortobifemoral bypass, axillofemoral or axillobifemoral bypass, and femoropopliteal bypass.

The procedure of choice depends on the location and severity of the patient’s arterial occlusion and on her overall medical condition. Before reconstructive surgery is performed, the physician will treat other medical problems that may interfere with healing, such as infection.

Bypass grafting is done with grafts made of Dacron, polytetrafluoroethylene, or other synthetic materials. Sometimes, one of the patient’s veins is used for the bypass. However, the vein that’s used must be free from disease. By restoring circulation to the affected limb through a bypass, the physician may be able to avoid or minimize amputation.

Bypass surgery is indicated for intermittent claudication only if the patient has unresponsive foot ulcers, infections, or gangrene or if the pain interferes with her occupation. If the occlusion is isolated, percutaneous transluminal angioplasty of the femoral, iliac, or popliteal artery may be performed. It may be used with laser angioplasty to open the artery and enhance blood flow.