In type 1 diabetes, the pancreas produces little or no insulin, the hormone that allows glucose to enter cells. Once glucose enters a cell, it is used as fuel. Without adequate insulin, glucose builds up in the bloodstream instead of going into the cells. The body is unable to use this glucose for energy regardless of the high levels in the bloodstream, leading to increased hunger. In addition, the high levels of glucose in the blood cause the person to urinate more, which leads to increased thirst. Within 5 to 10 years after diagnosis, the insulin-producing cells of the pancreas are completely destroyed, and no more insulin is produced.