Diabetes
Glucose is one of the most important tests to a diabetic. The fasting blood glucose (FBG) level is used to screen for and diagnose diabetes and pre-diabetes. It is usually done as part of a regular physical, is ordered when someone has symptoms suggesting diabetes, and is ordered routinely when a person presents to the emergency room with an acute condition.
According to the American Diabetes Association, a fasting plasma glucose, an oral glucose tolerance test (OGTT), or an A1c test may be used to diagnose diabetes and pre-diabetes. Each test has advantages, disadvantages, and limitations. For example, the FBG requires an 8 hour fast. The OGTT requires that the patient have a fasting plasma glucose test, followed by the patient drinking a standard amount of glucose solution to "challenge" their system, followed by another plasma glucose test 2 hours later. With the A1c, people don't have to fast for 8 hours or endure multiple blood samples being taken over several hours, but the test is not recommended for everyone. It should not be used for diabetes diagnosis in pregnant women, people who have had recent severe bleeding or blood transfusions, those with chronic kidney or liver disease, and people with blood disorders such as iron-deficiency anemia, vitamin B12 anemia, and hemoglobin variants. Also, only A1c tests that have been referenced to an accepted laboratory method (standardized) should be used for diagnostic or screening purposes. Currently, point-of-care tests, such as those that may be used at a doctor's office or a patient's bedside are too variable for use in diagnosis but can be used to monitor treatment (lifestyle and drug therapies).
If the initial test result is abnormal, the test should be repeated on another day to confirm a diagnosis of diabetes. Gestational diabetes is usually diagnosed using a glucose challenge test (GCT) as a screen, followed by OGTT if the screen is abnormal, per recommendations of the U.S. Preventive Services Task Force.
Sometimes random urine samples are tested for glucose, protein, and ketones during a physical. If glucose and/or protein or ketones are present on the indicator strip dipped in the urine sample, the patient has a problem that needs to be addressed. This is a screening tool, but it is not sensitive enough for monitoring.
Diabetics must monitor their own blood glucose levels, often several times a day, to determine how far above or below normal their glucose is and, based on their doctor's instructions, what modifications they should make to their medications. This is usually done by placing a drop of blood (obtained by pricking your skin with a small lancet device), onto a glucose strip and then inserting the strip into a glucose meter, a small machine that provides a digital readout of the blood glucose level.
A1c (also called hemoglobin A1c or glycohemoglobin) is a test that, in addition to being used for screening and diagnosis, is also ordered several times a year to monitor patients with type 1 or type 2 diabetes. It is a measure of the average amount of glucose present in the blood over the last 2 to 3 months and helps the doctor to determine how well a treatment plan is working to control the patient's blood glucose levels over time.
Microalbumin, often ordered as a microalbumin/creatinine ratio, is a test that measures very small amounts of protein in the urine (microalbuminuria). This is a symptom of the very early stages of kidney disease. Microalbumin is usually measured annually.
Urine and/or serum ketone tests may be ordered to monitor patients who present at the emergency room with symptoms suggesting acute hyperglycemia and to monitor patients who are being treated for ketoacidosis. A build-up of ketones can occur whenever there is a decrease in the amount or effectiveness of insulin in the body.
Several other laboratory tests may be used to monitor diabetes, evaluate organ function, and detect emerging complications. These include:
To monitor kidney function:
Creatinine Clearance, GFR, EGFR, CMP, BUN, Creatinine, Cystatin C
To monitor cholesterol and other lipids:
Cholesterol, HDL cholesterol, LDL cholesterol, Triglycerides, Lipid profile
