See these links for some symptoms that require immediate medical care:
Dog Emergencies  Important signs indicating that your diabetic dog needs immediate medical attention.
See Recordkeeping for details on what information should be prominently displayed near your diabetic pet in case of emergency.
The following lists emergency veterinary hospitals worldwide 
The following conditions are emergencies -- they require prompt intervention or veterinary treatment.
- Addisonian Crisis/Addisonian Shock Addison's disease
- Hypoglycemia Diabetes Mellitus
- Ketoacidosis Diabetes Mellitus
- Myxedema Coma Hypothyroidism
- Nonketotic hyperosmolar syndrome Diabetes Mellitus
- ↑ Dog Emergencies. Intervet.
- ↑ Emergency Veterinary Hospitals/Clinics Worldwide. Veterinary Emergency & Critical Care Society.
- Endocrine Emergencies DVM 360 October 2008