Background and Aims

A model of exercise effect on glucose utilization (GU), in healthy (ND) and type 1 diabetes subjects (T1D) has been recently proposed (Romeres et al. ATTD 2019, ADA 2019). It assumed that exercise acts both on insulin-independent (IIGU) and insulin-dependent GU (IDGU). The model was able to fit plasma glucose concentration during different clamp conditions. The aim of this study was to validate model-derived against model-independent measurement of GU.

Methods

Six ND (age=28.2±4.2 yrs., BMI=23.6±1.0 kg/m², VO_2max=36.6±2.9 ml/kg/min) and six T1D (mean±SE age=29±3 yrs., BMI=28.3±2.0 kg/m², VO_2max=28.7±2.9 ml/kg/min) were studied with a glucose clamp during, before and after a 60min exercise session at 65% VO_2max, on three visits: euglycemia-low insulin; euglycemia-high insulin and hyperglycemia-low insulin in random order.

Glucose turnover was measured with the isotope dilution technique using [6,6-²H₂]glucose and the model-independent GU was then calculated.

The model of exercise effect on GU was incorporated in the two-compartment model of glucose kinetics assuming an exercise-induced rapid effect on IIGU and a delayed effect on IDGU.

Results

Model predicted GU matches the model-independent GU (Figure 1), before, during and after the exercise session, both in ND and T1D.

Conclusions

We validated the model of exercise effect on GU against gold-standard data. The model is suitable to be incorporated into the UVa/Padova T1D simulator. This will permit in silico optimization of insulin therapy for artificial pancreas algorithms during physical activity.