Symptoms of type 1 diabetes usually appear rapidly as uncontrolled high blood glucose, or hyperglycemia, reaches crisis levels. Symptoms include the following:

• Excessive thirst

• Frequent urination

• Extreme hunger

• Unexplained weight loss

• Fatigue, or a feeling of being “rundown” and tired

• Rapid breathing

• Blurred vision

Diabetic Ketoacidosis (DKA)

When blood glucose levels are extremely high (above 250 mg/dl or 13.9 mmol/l), signs of DKA may also start to appear. Ketoacidosis is life-threatening and requires immediate medical attention. Symptoms and signs of DKA include the following:

• Lethargy

• Nausea and vomiting

• Abdominal pain

• Fruity breath odor

• Rapid breathing

• Dehydration

• Loss of consciousness

DKA is also diagnosed by the presence of ketones in the blood (and urine). (For more on urine testing for ketones, see Chapter 6.)

Hyperglycemic Hyperosmolar Nonketotic Coma (HHNC)

Although most common in people with type 2 diabetes, individuals with type 1 diabetes can also develop a condition known as hyperglycemic hyperosmolar nonketotic coma (HHNC), which is characterized by many of the same symptoms as DKA, and occurs when blood sugar levels are in excess of 600 mg/dl (33.3 mmol/l). HHNS is rare in type 1 diabetes.