Inclusion Criteria:

- Age 6 to 18 years

- Obesity with body mass index > 97 percentile or > 2 SD

- Hypothalamic-pituitary lesions not evolutive

- Hyperinsulinemia defined by insulin peak after oral glucose tolerance test>100 UI/L

- Absence of diabetes mellitus defined by basal plasma glucose < 1.2 g/L and glucose
peak after oral glucose tolerance test < 2 g/L and HbA1c < 7 %

- Hormonal replacement therapy stable from at least three months excluding the
treatment of diabetes insipidus which can be adjusted

- Normal plasma thyroxine

- Written informed consent of the children and the parents

Exclusion Criteria:

- evolutive lesion

- recent surgery or radiotherapy (< 6 months)

- modification of hormonal replacement therapy during the three previous months

- diabetes mellitus defined by basal plasma glucose > 1.2 g/L and glucose peak after
oral glucose tolerance test > 2 g/L and HbA1c > 7 %

- renal or hepatic failure

- uncontrolled hypertension

- hypersensitivity to benzothiazine drugs

- pregnancy

- difficulties to understand the protocol