Having low level of sebum refers to dry skin and this can subject a person to be prone to sensitivity.  The skin becomes parched looking due to the inability of the skin to retain moisture.  It usually feels "tight" and uncomfortable after washing unless some type of moisturizer or skin cream is applied.  The signs of extremely dry skin are chapping, cracking and dehydrated skin.

Dry skin can also be caused by by a deficiency in Vitamin A, B and E in the body.  To help reduce this problem, you should take in of plenty of fruit juices, a diet consisting of leafy vegetables.

Often extreme climatic conditions, wind and sunburn can cause the skin to become dry.  The outer layer of the skin has an oily layer that is sometimes not retained properly because of these conditions. The use of a humidifier is advised while staying in a room with a heater for a long time.

Hereditary factors can also cause dry skin cases.  If the skin condition has been passed within a family from generation to generation, there is a bigger chance that one would be bogged by the problem. 

You can visibly dry your skin when you are taking drugs and alcohol.  Prescription drugs such as diuretics, antihistamines and isotretinoin (Accutane) also have a drying effect.

One of the common causes of dry skin is also cold weather.  Moisture of the skin is naturally lost when the humidity is  significantly low and the climate or environment condition is very windy.
 
It would be appropriate that you would understand and determine the real causes of the skin condition before searching for treatment and prevention measures, practices and medications.