Does WLS reduce or cure Sleep Apnea?

Hello, I have a friend who is considering having weight loss surgery. I was under the impression that when something like Diabetes, sleep apnea, etc were considered co-morbidities, that that meant that the symptoms would be reduced or relieved after WLS. I know, I no longer have problems with Diabetes. But, not having any experience with sleep apnea, I am not sure. She is looking to me for advise. I would love to be able to tell her that her sleep apnea might go away after she has the surgery. But, I just don't know. She has to use a C-pap machine. Thanks, Joyce