Dark patches of skin

I know this is a symptom/side effect of PCOS. My sister has it pretty bad in her armpits, they're almost as dark as her Mauritian husband! I'm just wondering if anyone else has this, and particularly if anyone has the patches on their face?

I'm asking because I've just noticed today that both of my eyelids are dark and looking very rough/dry, but they feel normal when I touch them. I've upped my water intake, as it's been pretty shocking lately, so thought it might be a dehydration problem. I'm hoping it's not PCOS, because it's pretty damn visible, and not something I can remove like my man-beard!

I have the dark patches under my arms and so does my sister. Haven't had it on my face. My understanding is it is related to PCOS through insulin resistance and interestingly mine faded whilst I was taking metformin (anti diabetic). Now that I have stopped its gotten darker again. Have you been tested for insulin resistance?

Yes, I am insulin resistant but had a lot of trouble with Metformin. That was years ago though, apparently there is a nicer version of it now - will get on to my doctor and get started. Hopefully it works!