Diabetes Explained.com says that syringes come marked in either milliliter or cubic centimeter volume units. One cubic centimeter, or CC, is the same volume as one milliliter. When using a syringe to inject a medication, it is important to inject the correct volume to deliver the necessary dose.
The University of North Carolina's Eshelman School of Pharmacy explains that syringes are manufactured in various sizes depending on the volume that they can hold. In general, the smallest syringe that can hold the necessary volume should be selected, such as using a 3 cubic centimeter syringe for a 2.5 milliliter dose so that the volume markers can be in the smallest increments possible to increase the accuracy of the volume measurement.