Physical activity in patients with Type 1 diabetes: carbohydrate requirements for exercise and hydration strategies

INTRODUCTION: Maintaining homeostasis can be particularly complicated in diabetic individuals, especially during physical activity. Glucose is the primary metabolic fuel, and T1DM individuals have to adapt their therapy and diet in order to reduce the risk of glycemic perturbations, such as hypoglycemia or hyperglycemia. Fluid balance is relevant to preserve physical and cognitive performance, and elevated blood glucose levels are likely to increase fluid losses in urine. METHODS: Four studies will be presented combining T1DM, exercise, and hydration science. ECRES algorithm has been proposed to estimate the proper amount of carbohydrate (CHO) for exercise in diabetic individuals. In the first part of this thesis, ECRES algorithm was compared with individual strategies during a 24x1-h relay run; then it was compared with a reference method (REF) during moderate intensity walk on a treadmill. Hydration during training was investigated using a survey in both healthy and T1DM athletes, querying about their individual characteristics, sport characteristics, therapy (in T1DM individuals), and fluid intake behaviour. RESULTS: ECRES was found to suggest an amount of CHO similar to the amount actually consumed by T1DM when they were free to decide their own strategy (median, 38 and 30 g respectively, p = NS). Preliminary results from the validation study suggest that glycemic responses during exercise may be similar when estimated using ECRES or REF to estimate CHO needs. The hydration survey in healthy Italian athletes indicated that fluid intake during training was smaller than the volume suggested by international guidelines, and it is primarily influence by the number of pauses to drink, training duration, and coaches’ encouragement to drink. From preliminary results in T1DM individuals, fluid intake seems to be similar to healthy individuals, despite almost 1/4 of the sample reported to start the training with blood glucose above 180 mg/dL (10.0 mMol). CONCLUSIONS: Results from this thesis support the validity of ECRES algorithm in estimating the proper amount of CHO to prevent glycemic imbalances during exercise. Fluid balance is currently underrated in T1DM, despite its effects on performance and health: specific guidelines should be developed for diabetic athletes considering their behaviours and fluid requirements.