Not all medications can be cut, but Valium (diazepam) can be cut. This is done for a variety of reasons.
One of the main reasons why diazepam is cut is because it helps people achieve different dosage levels. This might be necessary during a time in which a patient is first monitored for signs of trouble while initially starting usage of this medication.
It also may be necessary any other time during the course of mental health treatment when the dosage needs to be decreased or increased. It also might be required in the event the patient is gradually weaned off of this medication when it is no longer necessary or safe to use.
In any case, most forms of Valium are scored. This allows for easy division of the tablets. Of course, reduction of a liquid dosage would be accomplished in a different way.
You should check with your doctor or psychiatrist before cutting this medication though. Oftentimes, trying to divide a timed-release tablet might not be recommended. However, the regular tablets often are more easily cut without harming your body.