Physiologic assessment of blood glucose homeostasis via combined intravenous glucose and insulin testing in horses

Abstract

Physiologically, the CGIT resulted in a 2-phase curve with positive (hyperglycemic) and negative (hypoglycemic) portions; the positive phase came first (250% of baseline at 1 minute). The descending segment declined linearly to baseline by approximately 30 minutes and to a nadir at 58% of baseline by 75 minutes. After a 35-minute valley, a linear ascent to baseline began. Addition of insulin in the CGIT increased glucose utilization by approximately 4.5 times during the positive phase but not during the negative phase. The diseases' effects and experimental inhibition of insulin secretion with xylazine and stress were detectable by use of the 2 phases of the CGIT. Only a single positive phase resulted from the GTT and a single negative phase from the IST CONCLUSIONS AND CLINICAL RELEVANCE: The CGIT resulted in a consistent, well-defined glycemia profile, which can be disrupted experimentally or by a disease process. The CGIT has clinical potential because it provides integrated information and more information than either the singular GTT or IST.

Laminitis and the Equine Metabolic Syndrome

“…66 Horses are tested through being administered both glucose and insulin (glucose, 150 mg/kg; insulin, 0.1 U/kg) and having the blood glucose concentration measured for 2 hours (12 blood glucose determinations at 0,11,15, 115, 125, 135, 145, 160, 175, 190, 1105, and 1120 minutes). Results of a CGIT are characterized by a two-phase curve with positive (hyperglycemic) and negative (hypoglycemic) portions.…”

“…If signs of hypoglycemia develop, patients should be treated using intravenous 50% glucose infusion. 66 Falsepositive results (suggesting IR in a normal horse) may arise if any stressful or exciting event precedes or occurs during the test. Therefore, the test should always be performed in a quiet environment in patients that have been allowed to consume a simple grass hay-based ration.…”

“…Normal insulin sensitivity is associated with a return to baseline within 45 minutes. 66 The testing conditions for a CGIT are the same as those for evaluating the patient's resting serum insulin and glucose concentrations.…”

“…Normal insulin sensitivity is associated with a return to baseline within 45 minutes. 66 The testing conditions for a CGIT are the same as those for evaluating the patient's resting serum insulin and glucose concentrations.Patients have a very small risk for development of signs of insulin-provoked hypoglycemia (weakness, trembling and sweating) during the test. If signs of hypoglycemia develop, patients should be treated using intravenous 50% glucose infusion.…”

<b>Avaliação da frutosamina em cavalos com e sem resistência à insulina</b>

“…O teste combinado de glicose e insulina (TCGI) é prático e capaz de fornecer informações quanto a dinâmica de glicose e insulina e ainda a interação entre estas variáveis (JHONSON, 2011), sendo desenvolvido a fim de refinar o diagnóstico de pacientes humanos com resultados inconclusivos frente aos testes de tolerância à glicose e tolerância à insulina por apresentarem valores marginais (EILER et al, 2005).…”