"Symptoms of diabetes include increased thirst and urination, increased hunger, fatigue, blurred vision, numbness or tingling in the feet or hands, sores that do not heal, and unexplained weight loss. Symptoms of type 1 diabetes can start quickly, in a matter of weeks. Symptoms of type 2 diabetes often develop slowly—over the course of several years—and can be so mild that you might not even notice them. Many people with type 2 diabetes have no symptoms. Some people do not find out they have the disease until they have diabetes-related health problems, such as blurred vision or heart trouble. Type 1 diabetes occurs when your immune system, the body’s system for fighting infection, attacks and destroys the insulin-producing beta cells of the pancreas. Scientists think type 1 diabetes is caused by genes and environmental factors, such as viruses, that might trigger the disease. Studies such as TrialNet are working to pinpoint causes of type 1 diabetes and possible ways to prevent or slow the disease. Type 2 diabetes—the most common form of diabetes—is caused by several factors, including lifestyle factors and genes. You are more likely to develop type 2 diabetes if you are not physically active and are overweight or obese. Extra weight sometimes causes insulin resistance and is common in people with type 2 diabetes. Extra belly fat is linked to insulin resistance, type 2 diabetes, and heart and blood vessel disease. Type 2 diabetes usually begins with insulin resistance, a condition in which muscle, liver, and fat cells do not use insulin well. As a result, your body needs more insulin to help glucose enter cells. At first, the pancreas makes more insulin to keep up with the added demand. Over time, the pancreas can’t make enough insulin, and blood glucose levels rise. Certain genes may make you more likely to develop type 2 diabetes. The disease tends to run in families and occurs more often in African Americans, Alaska Natives, American Indians, Asian Americans, Hispanics/Latinos, Native Hawaiians, and Pacific Islanders. Genes can also increase the risk of type 2 diabetes by increasing a person’s tendency to become overweight or obese. Gestational diabetes is caused by the hormonal changes of pregnancy along with genetic and lifestyle factors. Hormones produced by the placenta contribute to insulin resistance, which occurs in all women during late pregnancy. Most pregnant women can produce enough insulin to overcome insulin resistance, but some cannot. Gestational diabetes occurs when the pancreas can’t make enough insulin. Extra weight is linked to gestational diabetes. Women who are overweight or obese may already have insulin resistance when they become pregnant. Gaining too much weight during pregnancy may also be a factor. Having a family history of diabetes makes it more likely that a woman will develop gestational diabetes, which suggests that genes play a role. Genes may also explain why the disorder occurs more often in African Americans, American Indians, Asians, and Hispanics/Latinas. Genetic mutations, other diseases, damage to the pancreas, and certain medicines may also cause diabetes."