Blood sugar or also known as blood glucose is define as the concentration of sugar in a form of glucose per unit volume of blood being sample. The unit of blood sugar is in mg/dL or mg/100 mL since 1dL equals 100 mL. If we are given a blood sugar of 120 mg/100 mL which is also equal to 100 mg/dL, it only means that you have a 120 mg of glucose present in a 100 mL of blood sample. Normal blood sugar actually depends on where you are located. In US, the normal blood sugar is from 70 to 120 mg/dL. Thus, if your are at 120 mg/dL , your are at the boundary between the normal blood sugar to that of possibilities og having a Diabetes.