Glucose is the most important test to a diabetic. The fasting blood glucose 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, either a fasting plasma glucose (about an 8 hour fast) or an oral glucose tolerance test (OGTT) may be used to diagnose diabetes and pre-diabetes, but it recommends the fasting plasma glucose test because it is easier, faster, and less expensive to perform. 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. If abnormal, either 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 is 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

To monitor insulin production:
Insulin, C-Peptide