Diabetes mellitus is one of the most common endocrine disorders in the dog. Although diagnosticsare relatively straightforward, treatment and especially adequate long-term monitoring arechallenging. To avoid complications, such as hypoglycemia, weight loss, diabetes ketoacidosis andurinary tract infections, adequate monitoring is indispensable. In this review different monitoringtools, such as history and clinical signs, single and serial blood glucose measurements, glycated bloodproducts, continuous glucose measurements and urine glucose will be evaluated. Because eachmonitoring technique has its limitations, the challenge for the veterinarian is to use an adequatecombination of these tools to obtain a good image of the patient’s glycemic status.