Methods used by a physician in diagnosing diabetes in children may include:

• Family history. Children with a family history of either type 1 or type 2 diabetes are more likely to get diabetes. Children with a family history of the disease should be screened every two years after age 10 or at time of puberty if it occurs earlier.
  
  
• Blood tests. These include the:
  
  
• Fasting plasma glucose test (FPG).  A sample of blood is taken from a vein after an individual has not had anything to eat or drink for eight to 10 hours. The blood is tested for the amount of glucose (blood sugar) in the sample. If the glucose level is at least 126 milligrams per deciliter (mg/dL), the physician suspects diabetes. Physicians usually make a diagnosis of diabetes when two FPG tests, done on different days, are greater than 125 mg/dL. A glucose reading of 100 to 125 mg/dL indicates prediabetes, a condition that also needs treatment.
  
  
• Oral glucose tolerance test (OGTT). The patient consumes a carbohydrate-rich diet for a few days, then fasts for 10 to 16 hours before the test. After a blood sample is drawn, the patient drinks a concentrated glucose liquid. Two hours later, blood glucose readings of 140 to 199 mg/dL indicate prediabetes and 200 or higher suggest diabetes.
  
  
• C peptide test. The cells in the pancreas that make insulin produce a protein called C peptide. Elevated levels indicate high levels of insulin in the body, an indication of type 2 diabetes rather than type 1.
  
  
• Autoantibody testing. This can reveal self-antibodies seen with type 1 diabetes but not type 2.