Like it or not, your skin may be an indicator of how long you live.
A study in the Journal of Gerontology (*), a study of both women and men showed a relationship between blood pressure and how wrinkled a person's skin is. The more wrinkles there are, the higher the blood pressure.
(* published by Unilever, so there may be corporate for-profit pseudo-science)
It's hardly conclusive proof, but both blood pressure and skin can be linked to poor diet and poor health.
Exposure to the sun and "skin treatments" were shown not to be a factor. Skin on parts of the body that aren't usually exposed to the sun was also examined and showed the same tendencies.