what are some characteristics in urinalysis that can be used to diagnose diabetes.

Glucose and Ketones are excreted in urine. Glucose can also be found in urine if the kidneys are damaged so its not definative but if Ketones are in the urine you are definitely in ketoacidosis. This is a sign of fats being broken down in the blood stream. The body needs energy to function and if your body can't break down enough sugars because of lack of insulin then it breaks down fat for energy. This is also the basis for the Atkins diet.
Both of those analytes can be used to diagnose diabetes.