Millions of Americans have diabetes and don’t know it. But there are warning signs that could tell you it’s time to see a doctor to find out what’s wrong. Diabetes warning signs can range from very mild to severe. Most adults with type 2 diabetes report no symptoms. Their diabetes is discovered during routine blood testing. Other times, people have symptoms but ignore them for years. Both are risky. That's because diabetes can lead to bad health problems when it's left untreated. Type 1 diabetes is different. Affected individuals seek medical attention for their symptoms, and from there the diagnosis is confirmed. Here's what you should watch for. Common Signs of Diabetes See your doctor if you notice these warning signs and symptoms. Together you can make sure your blood sugar levels are in check. That will help you avoid problems that diabetes can cause. The most common signs and symptoms of diabetes are: Increased thirst and frequent urination. Diabetes is the leading cause of kidney disease. Healthy kidneys remove waste and extra fluid from the body. High blood sugar levels keep the kidneys from doing this job like they should. If you have diabetes, you might feel more thirsty than usual. You also might need to urinate more often than normal, even during the night. Fatigue. Having diabetes can make you extremely tired. This can be because of the changes in your blood sugar levels. It also can stem from lack of physical activity. Being overweight can have this effect too. Vision problems. Any change in eyesight could be a warning sign of diabetes. That includes blurry vision. Diabetes that's not controlled can lead to various eye problems. For instance, people with diabetes are more likely to get glaucoma than people who don't have diabetes. Cataracts also are more common among people with diabetes. People with diabetes are likely to get cataracts at a younger age and have them progress faster. Tingling or numb feet. Diabetes can lead to nerve damage. This often happens in the hands and feet. It may be due to changes in blood sugar levels. Damage to the blood vessels or nerves can also cause it. The first symptom of nerve damage is often numbness, tingling or pain in the feet. Symptoms usually start mild and get worse over time. Smoking and drinking alcohol can make matters worse. Skin infections or slow-healing sores. Diabetes can affect the whole body, including the skin. In fact, people with diabetes get bacterial and fungal infections more easily than others do. Skin infections or sores that heal slowly are early signs of the disease. Diabetes also can cause changes in small blood vessels. This can cause light brown, scaly patches of skin. These round or oval patches can be mistaken for age spots. Dry, itchy skin. Diabetes causes blood vessels in the feet and legs to harden and become narrow. This can lead to itching, especially in the lower leg. People with high blood sugar levels also are more likely to have dry skin. They also have a harder time fighting skin infections. Both dryness and infections can lead to itchy skin. Dark, velvety patches of skin. The name for this diabetes warning sign is acanthosis nigricans. It is often tied to obesity. People with the condition have tan or brown velvety raised patches in the folds and creases of their skin. Often they show up on the neck, armpits or groin. Sometimes they appear on the hands, elbows and knees. How Symptoms Differ Type 1 and type 2 diabetes are different. Their signs and symptoms can be too. For instance, people with type 2 diabetes are often overweight. People with type 1 diabetes may lose weight without trying. Symptoms of type 2 diabetes tend to develop slowly. But symptoms of type 1 diabetes often come on quickly. People who develop type 1 diabetes very fast may also have nausea, stomach pain, and vomiting.