Very imp thread.
IMO - based on my observations in my fitness club [and in my family]:
skin changes are different in stages of T2. 'Some of them' may include:
1. Pre-T2: brown or black patches mostly on upper body - around the neck, on lower back or under the breasts. In one or two instances, such patches were seen on thighs. These patches disappear after few months, especially after full onset of T2.
2. During T2 [controlled]: brown/ black patches on legs. May be permanent too.
3. Uncontrolled or high levels of BS/T2: discussion on 'patches' is meaningless during this phase, as mostly all organs [eyes, toes, teeth etc] are impacted. Usually surgical intervention is suggested to prevent the spread of gangrene.
I am not a medical doctor, much away from 'highly literate population' and I may be wrong totally; but this is what I observed. Feel free to hound me!
note: according to my observations/ notes: patches are seen in all T2 folks due to 'insulin resistance'.