Recovery of insulin sensitivity in mature horses after a 3 week course of dexamethasone therapy.

This study investigates the recovery period for insulin sensitivity in mature horses after a 21-day dexamethasone therapy, an anti-inflammatory drug. It shows that while glucose levels revert to normal within two days after treatment cessation, the enhanced insulin-secreting response maintains for a more prolonged period.

Methodology

• The study was conducted on eight healthy mature horses of mixed-breed. The horses were administered an oral dose of 0.04 mg/kg bwt/day dexamethasone for a duration of 21 days.
• Dexamethasone treatment was monitored by weekly blood samples taken on Days -21, -14, and -7, where Day -21 represents the baseline or normal blood level before dexamethasone intervention.
• After the final dexamethasone dose on Day 0, samples were collected on Days 1-6, 8, 10, 12, 15, and 22.

Results

• On the first day after the final dexamethasone dose, plasma glucose and insulin concentrations along with the modified insulin-to-glucose ratio (an indicator of pancreatic β cell responsiveness) were higher than the values seen at Day -21.
• The reciprocal of the square root of insulin, a measure of insulin sensitivity, was lower in comparison to Day -21 readings.
• Blood glucose concentrations dropped rapidly, returning to normal (Day -21) levels by Day 2. However, Insulin concentrations remained high until Day 3.
• The modified insulin-to-glucose ratio came down, matching the pre-dexamethasone levels by Day 4. Meanwhile, the levels indicating insulin sensitivity did not revert to Day -21 readings until Day 15.

Conclusion

• The results suggest that after dexamethasone treatment, blood glucose levels normalize rapidly within 2 days. However, the ability of the pancreas to secrete insulin (pancreatic insulin-secreting response) takes longer to recover.
• This contrast in recovery times indicates that the restoration of normal physiological markers following dexamethasone therapy can be variable, underscoring the need to understand individual recovery patterns for tailored therapeutic strategies.