Palatability, glycemic, and insulinemic responses to various carbohydrate formulations: Alternatives for the diagnosis of insulin dysregulation in horses?

Background: Oral glycemic challenge (GC) tests are recommended for diagnosis of insulin dysregulation (ID). Various protocols are used, but all have limitations in terms of palatability, ease of use, variable composition, geographic availability, or some combination of these.
Hypothesis/objective: To evaluate newly developed formulations with defined carbohydrate composition for use as oral GCs.
Animals: Thirty-four horses and ponies in various metabolic states.
Methods: Our objectives were carried out in 2 separate cross-over experiments. First, the palatability and acceptance of various GCs (2 syrups, 1 granulate) offered for free intake were compared to glucose mixed in a chaff-based diet. Subsequently, syrups were administered by syringe and compared to an oral glucose test using naso-gastric tubing (tube OGT) to investigate the glycemic and insulinemic responses. Second, these variables were compared in the best performing GC-formulations (granulate further optimized to pelleted formulation and 1 syrup) and a tube OGT. All GCs were administered with equivalent amounts of 0.5 g glycemic carbohydrates per kg body weight.
Results: Only the GC pellets were consumed completely by all horses (consumption time 5 ± 2 min). When administered by syringe, the GC syrup also was well accepted. The insulin concentrations at 120 min correlated significantly between tube OGT and GC pellets (r = .717; P < .001) or GC syrup (r = .913; P < .001). The new GC syrup and GC pellets discriminate between healthy and ID horses.
Conclusions and Clinical Significance: The GC pellets (DysChEq)™ and GC syrup can be used as palatable and well-accepted oral GC tests for assessment of ID in horses.
(© 2023 Boehringer Ingelheim Vetmedica GmbH and The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)