Estimation of insulin resistance in healthy and ketotic cows during an intravenous glucose tolerance test

Abstract

The objective of this study was to determine insulin resistance in healthy (n=8) and ketotic (n=7) dairy cows based on the difference between basal and dynamic changes in glucose, insulin, non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHB) concentrations, and on the determination of their mutual relationship and relationship with insulin resistance indices (RQUICKI and RQUICKI-BHB), after intravenous glucose tolerance test (IVGTT). The RQUICKI index showed a significant linear correlation (P lt 0.05) with basal insulin, glucose, NEFA and BHB levels. However, RQUICKI-BHB index values exhibited a negative correlation (P lt 0.01) with basal NEFA and BHB values and their clearance rates, as well as with glucose clearance rate, and a positive correlation (P lt 0.05) with basal insulin values as well as with insulin and glucose responses during IVGTT. The correlation between basal values of these parameters and the values measured or calculated during IVGTT is the result of RQUICKI-BHB values, as the exclusion of RQUICKI-BHB leads to loss of the statistical significance of the correlations between basal and dynamic values. Insulin resistance in ketotic cows is characterized by decreased insulin response to glucose and increased insulin resistance of the tissue, their correlation being the result of the RQUICKI-BHB index value.