The study is going to include 20 adolescents, 5-10 years after onset of T1D, aged 12-20 years, on insulin pump. The participants are going to have MRI of the head in euglycaemic and hyperglycaemic state. During both MRI, the participants are going to preform Flanker test, Tower of London test and Spatial memory test. The investigators are going to evaluate the response of inflammation markers and oxidative stress marekers in blood during hypreglycaemia.

The study is going to include 20 patientswith T1D. The group of patients is going to be homogeneous. The inclusion criteria are going to be: duration of T1D approximately 5 - 10 years, age between 10 and 24 years, without associated clinical complications of T1D, similar value of HbA1c and BMI within the normal range (depending on the percentile for age and sex), treatment with an insulin pump. Only the patients who are going to give written consent to participate in the form "Declaration of conscious and free consent" are going to be included.

All selected clinical data to determine the phenotypic characteristics of the patient will be obtained from available medical records or. at their regular outpatient reading.

After 12-hour fasting overnight, the patients will undergo 2h hyperglycaemic clamp.

During hyperglycemia a sample of venous blood for the evaluation of oxidative stress, inflammatory response and the expression of non-coding RNA is going to be drawn.

Subjects will have 1H-MRS in hyperglycaemic and euglycaemic state and evaluation of executive function (using psychological tests) is going to be preformed. For 1H-MRS, the MRI of the head in order to obtain anatomical data is going to be preformed at first .

Inclusion Criteria:

• T1D on insulin pump, no diabetic complication, normal BMI and blood pressure

Exclusion Criteria:

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