Comparison of measures of insulin sensitivity in early-lactation dairy goats

This experiment aimed to investigate the correlations between surrogate indices of insulin resistance (IR)-namely, the homeostasis model of IR, the quantitative insulin sensitivity check index, and the revised quantitative insulin sensitivity check index-and measures of IR obtained from an intravenous glucose tolerance test (IVGTT) performed in early-lactation dairy goats. Saanen goats (n = 26) with varying levels of milk production (1.7-4.8 kg/d) were selected and underwent an IVGTT on 43 ± 0.7 d postpartum (mean ± standard deviation). Data from the IVGTT were fitted in the minimal model to calculate parameters of glucose-insulin dynamics such as insulin sensitivity index and acute insulin response to glucose. Surrogate indices were computed using the average of the IVGTT basal samples. Correlation analysis revealed no relationship between surrogate indices of IR and measures of IR derived from the IVGTT (e.g., insulin sensitivity index, glucose clearance rate, glucose area under the curve). Therefore, our results suggest that surrogate indices of IR are not suitable for assessing the insulin sensitivity of peripheral tissue in early-lactation goats.