Changes in glucose tolerance and insulin secretion in a cohort of cats with chronic obesity.

Obesity, which is the most common spontaneous nutritional disorder in cats, is a known risk factor for the development of diabetes mellitus and has been linked to insulin resistance, hyperinsulinemia, and altered adipose-derived hormone secretion in cats. The objective of this study was to monitor and report changes in the results of serial intravenous glucose tolerance testing (IVGTT) and other metabolic parameters in 4 obese cats over a 4-year period. Serial IVGTT, insulin sensitivity indices, adipokine concentrations, and lipid profiles were evaluated. All cats had IVGTT changes consistent with impaired glucose tolerance and altered insulin secretory patterns during the 4-year study period. There was no significant increase in the fasting blood glucose or insulin concentrations and no changes in the insulin sensitivity indices evaluated. The mean adiponectin concentration decreased significantly over time, but there was no significant increase in the leptin concentration and no changes were observed in lipid profiles. Although IVGTT can be used to document early and/or mild impairment of glucose tolerance and changes in insulin secretory pattern, this test cannot be easily or readily carried out on client-owned cats in most clinical settings. More work needs to be done to establish reliable, convenient methods for earlier identification of cats at risk of developing clinical diabetes mellitus.