Blurred vision is the most common visual symptom of undiagnosed diabetes, and sometimes the first indication of diabetes a person notices. "The lens swells and changes shape, and people are out of focus," says Dr. Richard Hellman, president of the American Association of Clinical Endocrinologists (AACE).

Diabetes also can contribute to cataracts, which cloud eyesight, and glaucoma, which destroys side vision, usually so slowly it goes ignored. Regular eye exams can catch such problems and are an important part of your health care.

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