Metformin - for the last three months I have been taking one tablet a day for my type 2 diabetes in?

I have never heard of Metformin causing dark or black rings around the eyes.I did have a friend when his glucose levels were too high,he would have dark color under his eyes.Make sure you check your blood sugar regularly.And I would call my Physician if it continues.A lot of people are having allergy problems this year.Have you noticed anything realting to that issue.Clearing your throat,coughing or sneezing?I do know people who have allergies tend to have dark circles under their eyes.Or it could be a coincidance(sure I spelled that wrong)that u started this medication and it is not related to the Metformin.Check any other medications you are currently taking to make sure their are no drug interractions with the Metformin.Hope this helps and good luck.