The effect of oral and intravenous dextrose on C-peptide secretion in ponies.

This research study focused on understanding the regulation of insulin and the secretion of C-peptide in ponies, which can help manage hyperinsulinemia — a condition that could lead to laminitis if not properly managed. The study observed how oral and intravenous dextrose affects C-peptide secretion.

Objective of the Research

• The research aimed to explore the mechanisms of insulin dysregulation in ponies specifically with a focus on C-peptide. The peptide is released simultaneously with insulin but is not subjected to hepatic metabolism, thus making it a useful marker for studying insulin dysregulation.

Methodology Employed

• The study involved applying both oral and intravenous dextrose administration (0.75 g/kg) to nine ponies, which were previously categorized as hyperinsulinemic (HI) or normoinsulinemic (NI) based on oral glucose tests and fasted glucose-to-insulin ratios.
• Serial blood samples were collected post the dextrose administration for examining C-peptide secretion. The resulting responses from both oral and intravenous dextrose administration were then compared between the two groups of ponies (HI and NI).

Study Findings

• The study indicated that C-peptide concentrations increased rapidly from fasted levels when both oral and intravenous dextrose were used, showing that the injection forms didn’t make a significant difference in the area under the concentration-time curve (AUC).
• The research also identified that the AUC was roughly the same in hyperinsulinemic and normoinsulinemic ponies, suggesting that the pancreatic capacity was also similar in both groups when administered intravenously.
• Still, when administered orally, the AUC and the AUC were significantly higher in hyperinsulinemic ponies, suggesting that these ponies had a greater secretion rate of C-peptide.
• The research also proposed that slower insulin clearance might have contributed to the larger AUC in the hyperinsulinemic ponies, a hypothesis that requires further testing and specific measures of hepatic insulin clearance.