Tests and diagnosis

By Mayo Clinic Staff

If your child's doctor suspects diabetes, he or she will recommend a screening test. The primary test used to diagnose diabetes in children is the:

  • Random blood sugar test. A blood sample will be taken at a random time. Blood sugar values are expressed in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Regardless of when your child last ate, a random blood sugar level of 200 mg/dL (11.1 mmol/L) or higher suggests diabetes.

If your child's random blood sugar test results don't suggest diabetes, but your doctor still suspects it, your doctor may do a:

  • Glycated hemoglobin (A1C) test. This blood test indicates an 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 higher the blood sugar levels, the more hemoglobin that has sugar attached. An A1C level of 6.5 percent or higher on two separate tests indicates diabetes. A result of 5.7 to 6.4 percent is considered prediabetes, which indicates a high risk of developing diabetes.

Another test your doctor might use is a fasting blood sugar test. A blood sample will be taken after an overnight fast. A fasting blood sugar level less than 100 mg/dL (5.6 mmol/L) is normal. A fasting blood sugar level from 100 to 125 mg/dL (5.6 to 6.9 mmol/L) is considered prediabetes. If it's 126 mg/dL (7 mmol/L) or higher on two separate tests, your child will be diagnosed with diabetes.

Your doctor may also perform an oral glucose tolerance test. For this test, your child fasts overnight, and the fasting blood sugar level is measured. Then, your child drinks a sugary liquid, and blood sugar levels are tested periodically for the next several hours. A reading of more than 200 mg/dL (11.1 mmol/L) after two hours indicates diabetes. A reading between 140 and 199 mg/dL (7.8 to 11 mmol/L) indicates prediabetes.

If your child is diagnosed with diabetes, the doctor may do other tests to distinguish between type 1 and type 2 diabetes — which often require different treatment strategies because in type 1 diabetes, the pancreas no longer makes insulin.

After the diagnosis

At first, your child may need frequent visits to various members of his or her health care team, such as the doctor and dietitian. Once your child's blood sugar is stabilized, he or she will regularly visit his or her doctor to ensure good diabetes management.

The American Academy of Pediatrics (AAP) recommends A1C testing every three months to ensure blood sugar level goals are met. Your child's target A1C goal may vary depending on his or her age and various other factors. Ask your doctor what your child's A1C target is.

The American Diabetes Association has introduced a formula that translates the A1C into what's known as an estimated average glucose (eAG). The eAG more closely correlates with daily blood sugar readings. An A1C of 7 percent translates to an eAG of 154 mg/dL (8.5 mmol/L). That would mean that your child's average blood sugar levels are around 150 mg/dL (8.3 mmol/L) on most days.

Compared with repeated daily blood sugar tests, A1C testing better indicates how well your child's diabetes treatment plan is working. An elevated A1C level may signal the need for a change in your child's insulin regimen or meal plan.

Other periodic tests

In addition to the A1C test, the doctor will also periodically check your child's cholesterol levels, thyroid function, liver function and kidney function using blood and urine samples. The doctor will also examine your child to assess his or her blood pressure and make sure he or she is growing properly. Regular eye exams also are important.

Mar. 09, 2013