- blood pressure and heart rate (V0, V1, V2, V3). Biochemical evaluations (after a 12-h overnight fast): CBC with formula, serum insulin-like growth factor 1 (IGF1, ng/mL), 25-hydroxy (OH) vitamin D (ng/mL), uric acid (mg/dL), alkaline phosphatase (U/L), ACTH (pg/mL), cortisol (microg/dL), TSH (uuI/mL), fT4 (ng/dL) (V0, V1, V2, V3); aspartate aminotransferase (AST, IU/L), alanine aminotransferase (ALT, IU/L); AST-to-ALT ratio will be calculated as the ratio of AST (IU/L) and ALT(IU/L) (V0, V1, V2, V3); serum creatinine concentration (mg/dL) will be measured with the enzymatic method; according to the NKF-K/DOQI Guidelines for CKD in children and adolescents, the eGFR will be calculated using updated Schwartz's formula: eGFR (mL/min/1.73 m2) = [0.413 x patient's height (cm)] / serum creatinine (mg/dL) (V0, V1, V2, V3); glucose (mg/dL), insulin (μUI/mL); insulin-resistance (IR) will be calculated using the formula of Homeostasis Model Assessment (HOMA)-IR: (insulin [mU/L] x glucose [mmol/lL) / 22.5) (V0, V1, V2, V3); lipid profile: total cholesterol (mg/dL), High-Density Lipoprotein (HDL)-cholesterol (mg/dL), triglycerides (mg/dL); Low-Density Lipoprotein (LDL)-cholesterol will be calculated by the Friedwald formula and non-HDL (nHDL)-cholesterol will be also calculated(V0, V1, V2, V3); oral glucose tolerance test (OGTT: 1.75 g of glucose solution per kg, maximum 75 g) and samples willbe collected for the determination of glucose and insulin every 30 min. The area under the curve (AUC) for parameters after OGTT will be calculated according to the trapezoidal rule. Insulin sensitivity at fasting and during OGTT will be calculated as the formula of the Quantitative Insulin-Sensitivity Check Index (QUICKI) and Matsuda index (ISI). The stimulus for insulin secretion in the increment in plasma glucose as insulinogenic index will be calculated as the ratio of the changes in insulin and glucose concentration from 0 to 30 min (InsI). Βeta-cell compensatory capacity will be evaluated by the disposition index defined as the product of the ISI and InsI (DI) (V0, V1, V2, V3); a collection at rest of first-morning urine sample. Physical and chemical urinalysis; urine albumin (mg/L) will be determined by an advanced immunoturbidimetric assay and urine creatinine (mg/dL) will be measured using the enzymatic method. Urine albumin to creatinine ratio (u-ACR - mg/g), will be calculated using the following formula: [urine albumin (mg/dL) / urine creatinine (mg/dL)] x 1000. For these calculations both albumin and creatinine will be in the same unit. The subjects whose urine will be found positive, they will undergo a collection of two more samples and will be considered the u-ACR mean value of these (V0, V1, V2, V3). A sample of feces will be taken for microbic count (V0, V1, V2, V3). LPS (V0, V1, V2, V3). LPS will be measured with commercial kits (Limulus amoebocyte lysate assay) with standard procedures. Citokines IL1, IL1β, IL6, IL10, TNFα will be evaluated (V0, V1, V2, V3) (ELISA kit).