Test for Glycated Hemoglobin. Another test examines blood levels glycated hemoglobin, also known as hemoglobin A1c (HbA1c). Measuring glycated hemoglobin is not currently used for an initial diagnosis, but it may be useful for determining the severity of diabetes.
The basis for its use as a diagnostic measurement in diabetes is as follows:
- Hemoglobin is a protein molecule found in red blood cells. When glucose binds to it, the hemoglobin becomes modified, a process called glycation.
- Glycation affects a number of proteins, and elevated levels of glycolated hemoglobin is strongly associated with complications of diabetes.
- A glycated hemoglobin level of 1% above normal range identifies diabetes in 98% of patients. Normal HbA1c levels do not necessarily rule out diabetes, but if diabetes is present and levels are normal, the risk for complications is low.
The test is not affected by food intake so it can be taken at any time. A home test has been developed that might make it easier to measure HbA1c. In general, measurements suggest the following:
- Normal HbA1c levels should be below 7%.
- Levels of 11 - 12% glycolated hemoglobin indicate poor control of carbohydrates. High levels are also markers for kidney trouble.
Testing for Insulin Resistance. Investigators hope that some day a simple test for insulin resistance will be available that will be able to identify people at risk for diabetes. Some research suggests that measuring insulin and triglyceride levels during a fasting period may predict a person's sensitivity to insulin.
Autoantibody Tests
Type 1 diabetes is characterized by the presence of a variety of antibodies called autoantibodies that attack the islet cells. These antibodies are referred to as autoantibodies, because they attack the body's own cells -- not a foreign invader. Blood tests that test for these autoantibodies can help differentiate between type 1 and type 2 diabetes.
Screening Tests for Complications
Screening for Heart Disease. All patients with diabetes should be tested for high blood pressure (hypertension) and unhealthy cholesterol and lipid levels and given an electrocardiogram. For cholesterol, people with diabetes should aim for LDL levels below 100 mg/dL, HDL levels over 50 mg/dL, and triglyceride levels below 150 mg/dL. Blood pressure goals should be 130/80 mmHg or lower. Other tests may be needed in patients with signs of heart disease.
High blood pressure is strongly associated with diabetic nephropathy (kidney disease). In fact, patients with type 2 diabetes who show signs of microalbuminuria typically already have hypertension. Type 1 diabetes patients with microalbuminuria, on the other hand, usually have normal blood pressure readings in the doctor's office. A 2002 study using home monitors, however, found that in type 1 patients, high systolic blood pressure during sleep often occurs before development of nephropathy. (Systolic pressure is the first and higher number in a blood pressure reading.) Home blood pressure monitoring, may help identify type 1 patients at risk for kidney damage.
Previous Section
