If high blood sugar isn't controlled, blood vessels all over the body become damaged. Ongoing high blood sugar affects organs, blood vessels, and nerves. This raises the risk of damage to the heart, kidneys, eyes, nerves, and limbs. Diabetes also makes other problems more dangerous. These include high blood pressure, high cholesterol, and triglycerides. Over time, people with uncontrolled high blood sugar have a greater risk of being disabled or dying from serious conditions. These include heart attack, heart failure, or stroke. They may also have problems in their eyes, kidneys, and nerves, mainly in their feet and lower legs. Many of these problems may be due to the narrowing of blood vessels and poor circulation.