What Causes Sticky/oily Hair With Irregular Periods?

My daughter is 20 years old and in the past year to year and half, her hair has become very sticky and oily. Washing it doesn't seem to help and she does not use any products other than shampoo and light conditioner. She also has irregular periods. I (her mother) has diabetes and her dad has hypothyroid. Can her hair problems be caused by a medical problem?