Even before you know you have high blood sugar, your skin could be signaling it with a sign called a plaque. “Too much blood sugar leads to changes in blood vessels in the skin,” explained Hu. This results in shiny, thickened areas known as plaques. Areas ofhyperpigmentation, or darkened skin tone, can also arise due to underlying diabetes. As diabetes progresses, elevated blood sugar can interfere with your skin’s ability to serve as a barrier. As you lose circulation and sensation, you also compromise the ability of healthy skin to fight off infections. This is why people with diabetes are strongly advised to check their feet daily for small cuts and sores and to treat them immediately to prevent dangerous complications.