Investigation of glucagon-like peptide-1 response to six oral carbohydrates in ponies.

This study explores the relationship between glucagon-like peptide-1 (GLP-1), a hormone involved in insulin regulation, and the consumption of six different carbohydrates in ponies. The findings suggest that although GLP-1 responses to the carbohydrates are closely correlated with insulin concentrations, its utility in diagnosing insulin dysregulation or insulin resistance is not supported.

Study design and methodology

• The study involved 12 adult ponies of mixed Insulin Dysregulation (ID) status.
• Ponies were fed with different types of forages including hay, soaked hay, or haylage, which were then compared with four dynamic tests for Insulin Dysregulation.
• The dynamic tests included an in-feed oral glucose test (OGT), oral sugar test (OST), a test using a proprietary breakfast cereal (WEET), and a combined glucose-insulin tolerance test (CGIT).
• GLP-1, glucose, and insulin concentrations were measured before and after each feeding/test.
• Ponies were categorized as ID or non-ID and Insulin Resistant (IR) or non-IR based on the results of the OGT and CGIT, respectively.

Key findings

• All interventions, except the CGIT, initiated a GLP-1 response in the ponies within 30 minutes.
• The Oral Glucose Test and the WEET interventions that contained the greatest dose of non-structural carbohydrate induced a greater GLP-1 response compared to other interventions.
• The study didn’t find a detectable difference in the GLP-1 response according to the ponies’ ID or IR status.
• There were strong positive correlations between the GLP-1 and insulin concentrations measured at individual points in time and as an Area under the Curve (AUC) indicating their interrelation.

Conclusion

• The collected data did not support the use of GLP-1 as a supplementary diagnostic tool for Insulin Dysregulation or Insulin Resistance as defined by common intravenous or oral dynamic tests.
• Despite the strong correlation between GLP-1 and insulin concentrations, the GLP-1 hormone doesn’t appear to be a reliable marker for diagnosing conditions of insulin dysregulation or resistance in ponies.