Tests and diagnosis
By Mayo Clinic staff
Home blood sugar monitoring
You can determine if you have low blood sugar by using a blood glucose meter — a small computerized device that measures and displays your blood sugar level. You have hypoglycemia when your blood sugar level drops below 70 milligrams per deciliter (mg/dL) or 4 millimoles per liter (mmol/L).
It's important to record the date, time, test results, medication and dosage, and diet and exercise information each time you test your blood. Also, note any low blood sugar reactions. Your doctor diagnoses hypoglycemia using your records and looks for patterns to see how your medications and lifestyle affect your blood sugar.
Glycated hemoglobin (A1C) test
Your doctor may also conduct an A1C test. This blood test indicates your average blood sugar level for the past two to three months. It works by measuring the percentage of blood sugar attached to hemoglobin, the oxygen-carrying protein in red blood cells. The A1C test confirms your home blood sugar monitoring results and determines the effectiveness of your diabetes treatment program.
How often you need the A1C test depends on the type of diabetes you have and how well you're managing your blood sugar. Most people, however, receive this test between two and four times a year.
- Cryer PE. Glucose homeostasis and hypoglycemia. In: Kronenberg HM, et al. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa.: Elsevier Saunders; 2008. http://www.mdconsult.com/das/book/body/172399185-6/0/1555/204.html?tocnode=54108916&fromURL=204.html#4-u1.0-B978-1-4160-2911-3..50035-2_3179. Accessed Nov. 19, 2009.
- McCulloch DK. Management of hypoglycemia during treatment of diabetes mellitus. http://www.uptodate.com/home/index.html. Accessed Nov. 9, 2009.
- Hypoglycemia (low blood glucose). American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hypoglycemia-low-blood.html. Accessed Nov. 19, 2009.
- Hypoglycemia. National Institute of Diabetes and Digestive and Kidney Diseases. http://diabetes.niddk.nih.gov/dm/pubs/hypoglycemia/hypoglycemia.pdf. Accessed Nov. 19, 2009.
- A1C. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/a1c/. Accessed Dec. 2, 2009.

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