Diabetes Mellitus (DM) is a very common endocrinopathy in the clinical routine of small animals. Such disease, according to its cause, can be classified as type I or type II, the latter being the most frequent found in felines. The main clinical signs in cats may include polyuria, polydipsia, polyphagia, anorexia, lethargy, dry and dull fur, and poor hygiene of hair. Diagnosis is challenging and requires a series of tests to confirm and start treatment. To be successful in the treatment and to achieve possible remission of the condition, an individualized therapeutic plan should be made for each animal, whose main objective is the control of blood glucose, especially through insulin therapy and correction of the patient's diet, which is the theme. main part of this review.