Temperature Gradient Evolution (∆t) and Glycaemia as Complementary Parameters for Diagnosis and Treatment Monitoring of Glucose Metabolism Disorders
Authors: V Coulic 
Published: December 2021

Background: Anaesthesia and surgical interventions cause significant changes in body temperature and glycaemia control in human and in animals. Different measures were successfully applied to counter these changes. On the other hand, the treatment of acute or chronic glucose metabolism disorders based only on the evolution of serum glucose is not entirely satisfactory, using a device (ADD/) to measure the evolution of core/ deep and surface body temperatures and their difference (∆t), we investigated the relation between ∆t and glycaemia during anaesthesia in healthy and diabetic animals (rats) and during surgical operations in humans. Therefore, we followed the spontaneous evolution of glycaemia and body temperatures during anaesthesia and surgical stress, with or without interventions (insulin and glucose perfusion) to verify/justify the possibility of the intervention monitoring following ∆t evolution. Methods: Fifty two Wistar rats were used, 26 as controls and 26 with an experimental diabetes induced with streptozotocin to investigate the effect of anaesthesia and surgical stress alone. Another group of 26 Wistar rats were used in the same conditions plus insulin and glucose intravenous injection. The experiments were conducted in standard conditions of room temperature. After anaesthetics administration glycaemia was measured every 15-30min. Deep and superficial temperatures and their difference ΔT were registered continuously using an ADD device. Results: In intact anaesthetized animals after a slight elevation during the first 30 minutes, glycaemia decreased regularly with time during anaesthesia body temperature gradient (∆t) absolute values depended on the position of the temperature sensors and on ambient temperature, but their evolution was the same: slight initial decrease, stabilization and slight elevation before waking. Correlation between the two parameters was not evident. Thoracic surgery caused a more pronounced temperature decrease and glycaemia changes than anaesthesia alone (∆t not measured). In diabetic animals, as a rule glycaemia remained high during the operation time, the variations of ∆t values were more important and prolonged, as a rule ∆t was lower in diabetic animals than in healthy ones. Correlation with glycaemia could not be detected. Comparison between investigation results in animals before and after diabetes induction has pointed the important differences due to the disease and confirmed that ∆t reactions always preceded glycaemia ones) that explain the absence of correlation between these parameters). In all the series anaesthetic overdose could cause a temporary negative ∆t even in presence of normo- or hyperglycaemia. Ambient temperature elevation >30°C during the sessions caused an increase of all investigated features absolute values but none of their evolution. Taking into account the quick reaction of ∆t to modifications of external and internal conditions, monitoring glycaemia disorders by balanced insulin and glucose intravenous injection guided by ∆t evolution was tried with positive encouraging results. Clinical observations were added which results were close to the experimental ones, as well when concerning the influence of external (temperature) and internal (anaesthesia), metabolic factors, as when confirm possibility of monitoring insulin administration with energetic feedback. Conclusion: This study confirms that stress, ambient temperature and anaesthesia can alter both glycaemia and body temperature evolution, and that more profoundly in diabetes. It has shown a high sensibility of ∆t to the metabolic changes due to these factors. It ought to allow a valuable algorithm elaboration for glucose and insulin administration in automatic monitoring of energetic balance by a new ADD-CIGT device.