One of the most common symptoms of diabetes is excessive thirst, accompanied by excessive urination. You may feel thirsty despite drinking a lot of water. Even with the inconvenience of frequent trips to the bathroom, you may have an urge to keep guzzling.

Diabetes can also cause extreme hunger. You may feel ravenous even after putting away a big meal. Oddly enough, diabetes may cause you to lose weight even if you're overeating. This is no dieter's dream -- it should be a wake-up call to see a doctor.

A person with diabetes who ignores extreme thirst sometimes develops a dangerous level of dehydration and extremely high blood sugar. This condition, known as HHNS, can cause a coma or death. One-third of the cases of HHNS happen to people who don't even know they have diabetes, according to the American Diabetes Association.