Clinical Assessment of Blood Glucose Homeostasis in Horses: Comparison of a Continuous Glucose Monitoring System with a Combined Intravenous Glucose and Insulin Test Protocol

Abstract

Background: The combined glucose-insulin test (CGIT) is helpful for evaluating insulin sensitivity. A continuous glucose monitoring system (CGMS) reports changes in interstitial glucose concentrations as they occur in the blood. Use of the CGMS minimizes animal contact and may be useful when performing a CGIT.Hypothesis: Results obtained using a CGMS are useful for the evaluation of glucose responses during the evaluation of insulin sensitivity in equids.Animals: Seven mature, obese ponies. Methods: Ponies were equipped with CGMS for determination of interstitial glucose concentrations. Glucose (150 mg/kg, IV) and insulin (0.1 U/kg, IV) were administered and blood glucose concentrations determined at (minutes after time zero) 1, 5, 15, 25, 35, 45, 60, 75, 90, 105, and 120 with a hand-held glucometer. Blood chemistry results were compared with simultaneously obtained results using CGMS.Results: Concordance coefficients determined for comparison of blood glucose concentrations determined by a hand-held glucometer and those determined by CGMS after the zero time point were 0. 623, 0.764, 0.834, 0.854, and 0.818 (for delays of 0, 5, 10, 15, and 20 minutes, respectively).Conclusions and Clinical Importance: Interstitial glucose concentrations obtained by the CGMS compared favorably to blood glucose concentrations. CGMS may be useful for assessment of glucose dynamics in the CGIT.

Evaluation of Glucose Response to 3 Types of Insulin Using a Continuous Glucose Monitoring System in Healthy Alpacas

“…The CGM sensor and transmitter are normally implanted into the abdominal region of humans, and human skin is thinner and relatively fixed as compared to alpacas. Studies of other CGM systems in small animals, swine, and equine species placed the sensor in the subcutaneous space in the lateral cervical region caudal to the ear, along the dorsum, or lateral thoracic wall caudal to the scapula . The neck and thoracic areas would have been an ideal implant location except that alpacas can easily scratch these areas with their hind feet, and the ventral skin on the neck is very thick (over 0.5 cm in males).…”

“…Currently, veterinary hospitals that treat alpacas with these glycemic disorders use a variety of laboratory‐based and point of care (POC) glucometers. Continuous glucose monitoring (CGM) systems have been used for many years in human medicine and have more recently been evaluated in several animal species . The CGM systems utilize a sensor implanted into the subcutaneous which transmits glucose concentrations to a receiver for evaluation by the patient or health care provider.…”

Comparison of a continuous indwelling glucometer with a point‐of‐care device in healthy adult horses

“…These CIG systems have been reported to rapidly detect the trends towards hypoglycaemic or hyperglycaemic events, eliminating the need of frequent blood collections and allowing tight glucose surveillance 9. Interstitial glucose concentrations measured by CIG have been reported to be closely correlated with conventional blood glucose assay methods in people 15–19. Various studies have described the use of early CIG systems in healthy adult horses, critically ill neonatal foals and adult horses with chronic endocrinopathies with variable results 12 15 16.…”

Hypoglycaemia, hypoglycorrhachia, neuroglycopenia and glycaemic thresholds

“…A similar approach might be useful for the purpose of monitoring glucose status in horses at risk of hypoglycaemia (Johnson et al . ).…”

“…Significant benefits regarding the use of continuous glucose monitoring technology in human diabetic patients at risk for hypoglycaemic episodes have recently been presented (Harris et al 2010;Saw et al 2017). A similar approach might be useful for the purpose of monitoring glucose status in horses at risk of hypoglycaemia (Johnson et al 2011).…”