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 type 1 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 because of your child's symptoms, 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.

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 (7.0 mmol/L) or higher on two separate tests, your child will be diagnosed with diabetes.

If your child is diagnosed with diabetes, your doctor will also run blood tests to check for autoantibodies that are common in type 1 diabetes and help doctors distinguish between type 1 and type 2 diabetes. The presence of ketones — byproducts from the breakdown of fat — in your child's urine also suggests type 1 diabetes rather than type 2.

After the diagnosis

Once your child has been diagnosed with type 1 diabetes, he or she will regularly visit his or her doctor to ensure good diabetes management.

During these visits, the doctor will also check your child's A1C levels. Your child's target A1C goal may vary depending on his or her age and various other factors.

The American Diabetes Association (ADA) generally recommends slightly higher A1C levels for children and teens than for adults because children are less likely to notice the symptoms of low blood sugar levels. For children younger than age 6, the ADA recommends an A1C of less than 8.5 percent. In children between ages 6 and 12, the recommendation is for an A1C under 8 percent, and teenagers are advised to try to keep their A1C under 7.5 percent.

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.

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, as well as periodically test for celiac disease. The doctor will also examine your child to assess his or her blood pressure and growth and will check the sites where your child tests his or her blood sugar and delivers insulin.

Apr. 01, 2014