Acanthosis nigricans might be a clue that you have type 2 diabetes or are at risk of developing it. Type 2 diabetes has reached epidemic levels. Almost 10 percent of the US population has diabetes, and most cases are type 2. Unfortunately a very large number of diabetics remain undiagnosed. Many people do not have regular checkups with their doctor, therefore they wouldn’t know if they have diabetes. This is a problem because high blood sugar is extremely destructive in the body. It can harm the blood vessels, nerves, kidneys, eyes, the brain, the liver and the heart. Almost every organ in the body can suffer if your blood sugar level is too high. Acanthosis nigricans is a skin condition that causes dark, velvety discoloration. It particularly occurs in body folds and creases. The skin usually becomes thickened. The most common sites of the body to be affected are the armpits, groin and neck. The condition is a manifestation of insulin resistance; also known as syndrome X, pre-diabetes and metabolic syndrome. Therefore it’s most common in people who are overweight (particularly around their torso), women with polycystic ovarian syndrome and people with type 2 diabetes. If you notice this discoloration on your skin, please see your doctor and get your blood sugar checked.   http://www.mayoclinic.org/diseases-conditions/acanthosis-nigricans/basics/definition/con-20025600