Type 1 diabetes takes only a few weeks to develop. The initial symptoms are:

• increased production of urine (because the body tries to get rid of the excess glucose in the urine, diluting it with water),
• excessive thirst,
• fatigue (because the glucose is not being converted into energy),
• loss of weight,
• increased appetite,
• feeling sick,
• blurred vision,
• infections such as thrush or irritation of the genitals.

If type 1 diabetes is not treated at this stage, the body begins to produce chemicals called ketones that build up in the blood. This condition ? diabetic ketoacidosis ? causes additional symptoms:

• vomiting,
• stomach pain,
• rapid breathing,
• increased pulse rate,
• sleepiness.

Without treatment, diabetic ketoacidosis can lead to coma or death.

Signs and tests
The following tests can be used to diagnose diabetes:

• urinalysis shows glucose and ketone bodies in the urine, but a blood test is required for diagnosis
• fasting blood glucose is 126 mg/dL or higher
• random (nonfasting) blood glucose exceeds 200 mg/dL (this must be confimed with a fasting test)
• insulin test (low or undetectable level of insulin)
• C-peptide test (low or undetectable level of the protein C-peptide, a by-product of insulin production)

(From the National Institute of Health and Diabetes UK)