Evaluation of routine hematology profile results and fructosamine, thyroxine, insulin, and proinsulin concentrations in lean, overweight, obese, and diabetic cats.

To compare results of hematologic testing in nondiabetic and diabetic cats to identify possible indicators of alterations in long-term glucose control. Cross-sectional study. 117 client-owned cats (76 nondiabetic cats [25 with normal body condition, 27 overweight, and 24 obese] and 41 naïve [n = 21] and treated [20] diabetic cats). Signalment and medical history, including data on feeding practices, were collected. A body condition score was assigned, and feline body mass index was calculated. Complete blood counts and serum biochemical analyses, including determination of fructosamine, thyroxine, insulin, and proinsulin concentrations, were performed. Urine samples were obtained and analyzed. Glucose and fructosamine concentrations were significantly higher in the naïve and treated diabetic cats than in the nondiabetic cats. Insulin and proinsulin concentrations were highest in the obese cats but had great individual variation. Few other variables were significantly different among cat groups. Most cats, even when obese or diabetic, had unlimited access to food. Results suggested that cats at risk of developing diabetes (ie, overweight and obese cats) could not be distinguished from cats with a normal body condition on the basis of results of isolated hematologic testing. A longitudinal study is indicated to follow nondiabetic cats over a period of several years to identify those that eventually develop diabetes. Findings also suggested that dietary education of cat owners might be inadequate.