They require more time and commitment by the owner. The only way to know how the body is responding to the insulin is by taking blood glucose levels over the course of the day. Fructosamine levels can be taken every several weeks to determine long term response especially in cats that have high glucose readings due to the stress of drawing blood. Urine glucose levels can be used to monitor glucose levels at home if needed. Contact your veterinarian for specifics on monitoring.
Human insulin is the most commonly available insulin because that is what humans use.
Most dogs do well on human forms of insulin. It is available on an investigational basis. Usual Dose and Administration Doses vary considerably between patients. Doses may need to be given twice a day. Doses may need to be much higher to get the diabetes under control and then decreased.