Diabetes Mellitus, Feline - contd.
The diagnosis of diabetes mellitus is usually first suspected because of the presence of typical clinical signs. Since similar signs can be seen in other conditions, further evaluation is needed to confirm a diagnosis of diabetes mellitus and to rule out other disorders that can cause similar symptoms. On physical examination, diabetic cats may be either thin or overweight, but many will appear to have normal body condition. Weakness, depression, and dehydration may also be noted.
The diagnosis is based on the observation of these clinical signs as well as documentation of persistently elevated blood glucose concentrations and elevated urine glucose levels. Because stress can cause significant elevations of blood glucose levels in cats, and in rare circumstances, glucose can be seen in the urine of stressed cats, the measurement of a substance called fructosamine may help distinguish stress-induced changes in blood and urine sugar levels from true diabetes mellitus. In stressed cats, serum fructosamine concentrations are usually normal, but they are elevated in diabetic cats. Ketones are another substance that can appear in the urine of diabetic cats, but they are generally not seen due to stress.
There are many other parameters that need to be assessed in a suspected or confirmed diabetic cat once persistent blood and urine sugar levels are noted and stress is ruled out as a factor. A complete blood count is used to look for changes in the red blood cell, white blood cell, and platelet counts. A biochemistry profile may detect evidence of concurrent liver or kidney disease and electrolyte abnormalities. A thyroid hormone level should be checked to rule out hyperthyroidism, as this disease can cause the exact same signs as diabetes mellitus, and can also complicate management of diabetes in a cat that also has hyperthyroidism. However, sometimes hyperthyroidism cannot be ruled out by a single normal reading, as this hormone level can be falsely lowered in the presence of uncontrolled diabetes mellitus. Complete urinalysis and urine cultures are necessary to rule out a complication called ketoacidosis and to rule out urinary tract infection. Chest x-rays and abdominal ultrasound may also be recommended, depending on the cat's overall condition.
