The objectives of the study are: 1) to evaluate the effects of moderate exercise on SG evolution without insulin dose modification in patients with T1D under continuous subcutaneous insulin infusion (CSII) and multiple daily injection (MDI) therapy, and compare differences between these 2 groups; 2) to evaluate the impact of insulin dose modification (bolus, basal, reduction or increase, based on SG evolution profile obtained after first exercise) before and/or during moderate exercise on T1D children under CSII and MDI regimen, and compare differences between these 2 groups.

Intervention and procedures:

a) The patients will first be assigned to standardized moderate-to-vigorous exercise for SG determination; b) similar exercise will then be repeated with preemptive adaptation of insulin dose (tailored on SG evolution during first exercise) for determination of potential influences on SG evolution.

Intervention Plan:

• At first visit (day [>18h] before exercise): setting of a Continuous Glucose Monitoring System
• At second visit: moderate-to-vigorous exercise with treadmill.
• At third visit (2 days after exercise): removal of CGMS
• At fourth visit (day [>18h] before fifth visit): setting of a Continuous Glucose Monitoring System
• At fifth visit: moderate exercise with treadmill, and insulin dose modification (basal rate, bolus, reduction, increase)
• At sixth visit (2 days after exercise): removal of CGMS
• Total number of visits: 6
• The exercises will be performed between 1 and 2 hours after breakfast or after lunch; the second exercise will be performed ≥2 weeks after the first exercise.

Controls:

• Moderate exercise with and without modification of insulin dose in MDI patients (by comparison with CSII patients). MDI patients will be matched to CSII patients according to gender, age, BMI (±0.5 z-score) and HbA1C levels (±1%) to exclude any bias in patient allocation.
• Moderate exercise without modification of insulin dose at first visit (by comparison with modification of insulin dose).

Inclusion Criteria:

• Diagnosis of T1D (according to the ISPAD 2011 guidelines)
• T1D outside of partial remission phase (defined according to the IDAA1C definition [Diabetes Care 2007], being equal to A1C (%) + [4 x insulin dose (units per kilogram per 24 h)] and at least > 2 years after T1D diagnosis (defined as the first day of insulin therapy)

Exclusion Criteria:

• Non-type 1 diabetes
• Severe neonatal asphyxia (defined as Apgar score 3 or less after 5 min), children born small for gestational age, chronic systemic disease, active malignancy, hypothyroidism, hypopituitarism, developmental delay, bladder dysfunction, obesity, carnitine deficiency, β-oxidation defect, cardiac malformations, dysrhythmia
• Intake of drugs interfering with insulin sensitivity (e.g. corticosteroids, GH).
• HbA1C >9.5% at the time of enrollment in the study.