Tests and diagnosisBy Mayo Clinic staff
Your doctor sets your target blood sugar range. For many people who have diabetes, target levels are:
- Fasting at least eight hours (fasting blood sugar level) — between 90 and 130 mg/dL (5 and 7 mmol/L)
- Before meals — between 70 and 130 mg/dL (4 and 7 mmol/L)
- One to two hours after meals — lower than 180 mg/dL (10 mmol/L)
Your target blood sugar range may differ, especially if you're pregnant or you develop diabetes complications. Your target blood sugar range may change as you get older, too. Sometimes reaching your target blood sugar range is a challenge. But the closer you get, the better you'll feel.
Home blood sugar monitoring
Routine blood sugar monitoring with a blood glucose meter is the best way to be sure that your treatment plan is keeping your blood sugar within your goal range. Check your blood sugar as often as your doctor recommends.
If you have any signs or symptoms of severe hyperglycemia — even if they're subtle — check your blood sugar level. If your blood sugar level is 240 mg/dL (13 mmol/L) or above, use an over-the-counter urine ketones test kit. If the urine test is positive, your body may have started making the changes that can lead to diabetic ketoacidosis. You'll need your doctor's help to lower your blood sugar level safely.
Glycated hemoglobin (A1C) test
During an appointment, your doctor may 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.
An A1C level of 7 percent or less means that your treatment plan is working and that your blood sugar was consistently within the normal range. If your A1C level is higher than 7 percent, your blood sugar, on average, was above the normal range. In this case, your doctor may recommend a change in your diabetes treatment plan.
Keep in mind that the normal range for A1C results may vary somewhat among labs. If you consult a new doctor or use a different lab, it's important to consider this possible variation when interpreting your A1C test results.
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 with diabetes, however, receive this test between two and four times a year.
- Hyperglycemia (high blood glucose). American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hyperglycemia.html. Accessed Feb. 25, 2012.
- Your guide to diabetes: Type 1 and type 2. National Institute of Diabetes and Digestive and Kidney Diseases. http://diabetes.niddk.nih.gov/dm/pubs/type1and2/index.aspx. Accessed Feb. 25, 2012.
- Halter JB, et al. Hazzard's Geriatric Medicine and Gerontology. 6th ed. New York, N.Y.: The McGraw-Hill Companies; 2009. http://www.accessmedicine.com/content.aspx?aID=5133173. Accessed Feb. 25, 2012.
- Longo DL, et al. Harrison's Online. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/content.aspx?aid=9141196Accessed March 1, 2012.
- A1C. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/a1c/. Accessed Feb. 25, 2012.
- American Diabetes Association. Standards of medical care in diabetes — 2012. Diabetes Care. 2012;35:S11.
- Humphries RL, et al. Current Diagnosis & Treatment: Emergency Medicine. 7th ed. New York, N.Y.: The McGraw-Hill Companies; 2011. http://www.accessmedicine.com/content.aspx?aID=55757059. Accessed March 1, 2012.
- Collazo-Clavell ML (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 2, 2012.
- Diagnosis and management of type 2 diabetes mellitus in adults. Bloomington, Minn.: Institute for Clinical Systems Improvement. http://www.guideline.gov/content.aspx?id=24137. Accessed March 1, 2012.