A lightening or bleaching cream/lotion with Hydroquinone may help lighten the skin around the areola,but it is more than likely not safe or recommended,Hydroquinone isn't exactly safe for any part of the body or skin.Check with your doctor and I'm sure there's some medical procedure for this.
Ehh,it sucks balls having dark areolas:///(I do so don't get offended GIRLS)
Unless you can change your dna you're probably stuck with it. I think you're more likely to hurt yourself then succeed.
As a guy I just find it depressing that women are so desperate to change something about themselves that isn't a defect. It's becoming a serious problem when girls feel so much pressure to conform to an image that they have to change not just their clothes or style but their very bodies. It's almost tragic to me that girls with healthy, beautiful bodies want to do that themselves and it makes me angry to be honest. Dark areolas are not a defect.
Please believe me when I say that your areolas are not a turn off to men. If a guy bails on you because of your areolas, he's an asshole, end of story. The other 99% of guys will find them just as hot as lighter ones.
Nipple transplant. Yup.
I'm not going to give you a speech. I'm just going to say this as simply as possible:
No man cares if your nipples are what you consider to be "dark."