The Effects of a Progressive Dehydration Protocol on Glycaemic Response During and Following Exercise in Patients with Type 1 Diabetes

Abstract

The aim of this study was to assess whether progressively dehydrating Type 1 Diabetes Mellitus (T1DM) patients via fluid restriction around exercise affected glucose control during and following exercise, compared to euhydrated T1DM patients. It is hoped that this study can aid the formation of T1DM-specific fluid intake guidelines around exercise, based on alterations in glucoregulation and osmoregulation. The fluid restriction protocol induced a mild level of dehydration (1.1% body mass loss from pre-exercise measurements). Furthermore, dehydrated subjects displayed significantly greater post-exercise serum copeptin concentration (p<0.01), compared to resting and euhydrated subjects’ values. There was a trend for a greater glycaemic response during exercise and the post-exercise recovery period of the dehydration trial, but there were no significant differences in either the interstitial or blood glucose responses between trials. Although baseline serum glucagon concentrations were significantly different between trials (p<0.01), thereafter there were no significant differences between trials at any remaining timepoint. There was a statistically significant effect of trial on serum cortisol concentrations (p<0.01), with post-exercise serum cortisol concentrations remaining significantly greater during the dehydration trial, compared to euhydrated subjects’. Up to 48 hours following the dehydration trial, there was a significantly reduced prevalence of mild hyperglycaemia compared to the same period following the control trial (p<0.01), with a trend for a concomitant increase in euglycaemic interstitial glucose measurements. The discrepancies in acute glycaemic control occurred without an increased risk of hypoglycaemia, and were not attributable to any significant differences in total carbohydrate intake or total units of insulin administered. Further research is required to establish the intramuscular and intracellular physiology linking dehydration with alterations in whole-body and tissue-specific glucose metabolism. T1DM patients must therefore balance the potential short-term benefits of mild dehydration on acute glycaemic control, with long-term health consequences associated with regular dehydration and elevated vasopressin concentrations.