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Effect of varying the dose of corn syrup on the insulin and glucose response to the oral sugar test
Author(s) -
Jocelyn N. A.,
Harris P. A.,
MenziesGow N. J.
Publication year - 2018
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12826
Subject(s) - laminitis , insulin , crossover study , medicine , blood sugar , endocrinology , corn syrup , sugar , horse , diabetes mellitus , zoology , chemistry , food science , biology , placebo , paleontology , alternative medicine , pathology
Summary Background The oral sugar test ( OST ) is used to identify equine insulin dysregulation ( ID ); however only a dose of 0.15 mL/kg bwt corn syrup has been evaluated. Objectives To determine the effect of varying the dose of corn syrup on insulin and glucose response to the OST and the test's ability to distinguish between ponies with a history of laminitis ( PL ) and without laminitis ( NL ). Study design Randomised crossover experiment. Methods After an overnight fast, in a three‐way randomised crossover study with a 7‐day washout, 0.15, 0.3 or 0.45 mL/kg bwt corn syrup was administered orally to eight ponies (5 PL and 3 NL ) and blood obtained between 0 and 120 min. Serum [insulin] and [glucose] were measured using previously validated radioimmunoassay and colorimetric assays respectively. The repeatability of and the effect of continued pasture access on the dose that best distinguished PL and NL ponies were then assessed. The effect of dose, laminitis history and fasting on serum [insulin] and [glucose] responses were assessed using mixed‐effects models. Results The serum [insulin] following 0.15 mL/kg bwt were not significantly different from 0.3 mL/kg bwt at any time point, while serum [insulin] following 0.45 mL/kg bwt significantly (P<0.01) differed from 0.15 and 0.3 mL/kg bwt at all time points apart from 0 min. The serum [insulin] concentration significantly (P<0.01) differed between NL (mean 86 [95% CI 59, 113] μiu/mL) and PL (146 [95% CI 124, 167] μiu/mL) only following 0.45 mL/kg bwt at 60 min. Repeatability of serum [insulin] at 60 min following 0.45 mL/kg bwt dose under fasted conditions was 0.51. Using AUC insulin improved repeatability to 0.83. There was no significant difference between the fasted and at pasture results. Main limitations The OST was performed in small numbers of ponies on limited occasions. Conclusions A dose of 0.45 mL/kg bwt corn syrup may be preferable to differentiate PL and NL ponies.