Lisdexamphetamine Vs Methylphenidate for Pediatric Patients with ADHD and Type 1 Diabetes

Principal inclusion criteria: * Age 8-16.5 years at study entry; * T1D diagnosed on the basis of clinical features, presence of autoantibodies typical for type 1 diabetes (at least one of the following: anti-glutamate decarboxylase, islet cell antibody, insulin autoantibody/islet antigen 2 autoantibody, zinc transporter 8 antibody) and/or low C-peptide levels (according to the laboratory standard appropriate for the assay method) and criteria for the diagnosis of diabetes according to the criteria of the Polish Diabetes Association and international societies: * an incidental glycemia ≥200mg/dl and symptoms of hyperglycemia (such as increased thirst, polyuria, weakness) or * two times a fasting blood glucose ≥125mg/dl or * a blood glucose ≥200mg/dL in the 120th minute of an oral glucose load test or * HbA1c ≥6.5%. * T1D diagnosed at least 12 months before recruitment; * T1D treated with functional intensive insulin therapy * a diagnosis of ADHD according to Diagnostic and Statistical Manual 5 (DSM-5) criteria confirmed by a psychiatrist or a diagnosis of ADHD according to other criteria recognized in Poland, confirmed by an authorized person as consistent with DSM-5 * Polish citizenship and Polish health insurance Principal exclusion criteria: * Daily insulin dose\<0.3 j/kg and concomitant HbA1c measurement ≤6.5% from the last 3 months (clinical partial remission of T1D); * Severely unsatisfactory glycemic control - mean HbA1c over the past year ≥12% (not including HbA1c measurement at diagnosis of T1D); * Diagnosed intellectual or other disability that prevents participation in the trial or adherence to its therapeutic regimen; * Clinically apparent cardiovascular disease: recognized hemodynamically significant heart defect, advanced vascular atherosclerosis; * Diagnosis of other mental illness or disorder preventing participation in the trial, e.g. bipolar affective disorder, schizophrenia, other psychotic disorders, psychoactive substance abuse; * Diagnosed allergy or hypersensitivity to drugs used in pharmacological intervention -methylphenidate and/or lisdexamphetamine; * Language barrier making it impossible to conduct a full psychological consultation in Polish; * Lack of permanent residence in Poland; * Contraindications as reported for investigated drugs: documented hypertension (at least stage 2), positive family history for sudden cardiac deaths and atrial arrythmias in relatives below 40 y.o., clinically evident glaucoma or abnormally elevated intraocular pressure, history of suicide attempts or present suicide intentions, oppositional defiant disorder, chronic motor tics or Tourette syndrome, pregnancy or breastfeeding, short stature, underweight (≤ 3rd percentile for reference percentile charts), epilepsy, pheochromocytoma, substance abuse or positive drug test results, prolonged treatment with sedative drugs (e.g., 1st generation antihistamines); * Declared by the parents/legal guardians' inability or unwillingness to come to the Center at the time specified by the protocol, in particular - to pick up the Trial drugs at the dose adjustment stage (the need to pick up 4-5 times over 6-8 weeks, each time within 2-3 days of receiving the recommendations); * Other reasons that, in the opinion of the attending physician, are more likely to result in difficulties in maintaining the continuity of the participant's participation in the trial or harm to the participant's health in case of participation in the trial.