How can I tell if I have pre-diabetes?

In general less than 100 mg/dL (5.6 mmol/L ) is normal. 100 to 125 mg/dL (5.6 to 6.9 mmol/L ) is diagnosed as prediabetes. 126 mg/dL (7.0 mmol/L ) or higher on two separate tests is diagnosed as diabetes.