 Otherwise, a level below 2.8 mmol/L (50 mg/dL) after not eating or following exercise may be used.In newborns, a level below 2.2 mmol/L (40 mg/dL), or less than 3.3 mmol/L (60 mg/dL) if symptoms are present, indicates hypoglycemia.Other tests that may be useful in determining the cause include insulin and C peptide levels in the blood.