Variation in insulin response to oral sugar test in a cohort of horses throughout the year and evaluation of risk factors for insulin dysregulation.
Authors: Karikoski Ninja P, Box Justin R, Mykkänen Anna K, Kotiranta Veikko V, Raekallio Marja R
Journal: Equine veterinary journal
Summary
# Editorial Summary Insulin dysregulation remains challenging to diagnose reliably in individual horses, partly because the oral sugar test's seasonal stability has never been formally evaluated. Karikoski and colleagues followed 29 Finnish horses over a full year, performing the OST bimonthly alongside measurements of body condition, cresty neck score, adiponectin, and fasting glucose to determine whether insulin responses fluctuate seasonally and which factors predict dysregulation. Insulin concentrations and adiponectin levels proved remarkably consistent across seasons, yet 12 of 29 horses (41%) shifted between dysregulated and normal status at different time points—suggesting that single-point testing misses a meaningful proportion of metabolically variable individuals. Age, cresty neck prominence, and low adiponectin emerged as independent risk factors for elevated post-OST insulin peaks, whilst lack of exercise carried a sevenfold increased odds ratio for dysregulation compared to exercising horses; dysregulated horses also displayed longer necks, greater height, and significantly lower adiponectin than those remaining consistently normal. For practitioners, these findings underscore that exercise prescription and adiposity management—particularly crest management—warrant emphasis in metabolic prevention strategies, and that horses with variable risk factors or ambiguous initial test results may benefit from repeat OSTs across different seasons to capture their true dysregulatory status.
Read the full abstract on PubMed
Practical Takeaways
- •Repeated oral sugar tests throughout the year may be warranted for horses with variable insulin dysregulation status, as single testing may miss affected animals
- •Exercise appears protective against insulin dysregulation regardless of season; prioritize consistent movement programs for metabolic health
- •Monitor cresty neck score, adiponectin levels, and body composition in older horses as these are linked to insulin response; combine with clinical assessment rather than relying on seasonal patterns alone
Key Findings
- •Oral sugar test results and adiponectin concentrations did not vary significantly with season despite 12 of 29 horses showing variable insulin dysregulation status throughout the year
- •Increasing age, cresty neck score, and decreasing adiponectin were identified as risk factors for elevated maximum insulin concentration
- •Horses without exercise had 7.6 times higher risk of insulin dysregulation compared to horses with regular exercise (P = 0.03)
- •Horses with insulin dysregulation had significantly lower adiponectin, longer neck circumference, and greater height than non-dysregulated horses