Drinking more (polydipsia)
Urinating more (polyuria)
Weight loss
Lethargy
Increased appetite (polyphagia)
Cloudy eyes (cataracts)
Know the signs of hypoglycemia (lack of appetite, disorientated, tremors, vomiting, seizures) and what to do (feed them, use oral glucose, contact your vet)
Discuss spaying female dogs with your vet as this may help to control the diabetes.
Feed a high-quality diet.
Be consistent with insulin treatment.
Have regular communication and check-ups with your vet.