The symptoms of type 1 diabetes appear rapidly during a period of several weeks to a few months and often occur after an illness. In children and some adults, symptoms of diabetes may be similar to those of the flu. The most common symptoms of diabetes include:

• Extreme thirst (polydipsia)
  
  
• Excessive urination (polyuria) and bedwetting in children
  
  
• Increased appetite (polyphagia)
  
  
• Drowsiness, lack of energy or fatigue
  
  
• Changes in vision, such as increased myopia (nearsightedness)
  
  
• Unexplained weight loss
  
  
• Mood changes
  
  
• Sweet, fruity smelling breath, a sign of ketosis

A number of diabetic reactions may occur when glucose (blood sugar) is poorly managed. These conditions have specific symptoms and can cause additional medical problems. The most common reactions include:

• Hypoglycemia. When blood glucose is too low.
  
  
• Hyperglycemia. When blood glucose is too high.
  
  
• Diabetic ketoacidosis. Serious condition involving severe hyperglycemia and ketosis.

The first symptoms of type 1 diabetes may be ignored, leading to life–threatening ketoacidosis. This condition includes a buildup of ketones (acids) in the blood that can poison the body. Ketoacidosis can lead to a diabetic coma or even death.