by Amanda Gardner

Diabetes affects 24 million people in the U.S., but only 18 million know they have it. About 90% of those people have type 2 diabetes.

In diabetes, rising blood sugar acts like a poison.

Diabetes is often called the silent killer because of its easy-to-miss symptoms. “Almost every day people come into my office with diabetes who don’t know it,” says Maria Collazo-Clavell, MD, an endocrinologist at the Mayo Clinic in Rochester, Minn.

The best way to pick up on it is to have a blood sugar test. But if you have these symptoms, see your doctor.

Symptom #1:

Increased urination, excessive thirst

If you need to urinate frequently—particularly if you often have to get up at night to use the bathroom—it could be a symptom of diabetes.

The kidneys kick into high gear to get rid of all that extra glucose in the blood, hence the urge to relieve yourself, sometimes several times during the night.

The excessive thirst means your body is trying to replenish those lost fluids.

These two symptoms go hand in hand and are some of “your body’s ways of trying to manage high blood sugar,” explains Dr. Collazo-Clavell.