Tests and diagnosis

By Mayo Clinic Staff

Your doctor sets your target blood sugar range. For many people who have diabetes, Mayo Clinic generally recommends target blood sugar levels that are:

  • Between 80 and 120 mg/dL (4 and 7 mmol/L) for people age 59 and younger who have no other underlying medical conditions
  • Between 100 and 140 mg/dL (6 and 8 mmol/L) for people age 60 and older, those who have other medical conditions, such as heart, lung or kidney disease, or those who have a history of low blood sugar (hypoglycemia) or who have difficulty recognizing the symptoms of hypoglycemia

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.

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 target 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.

However, for some people, especially the elderly, people with other medical conditions, or advanced diabetes complications, a higher A1C level of up to 8 percent may be appropriate.

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.

April 18, 2015