Metformin in Obese Children and Adolescents

The prevalence of obesity in children and adolescents is increasing rapidly and is associated with significant medical and psychosocial consequences persisting into adulthood.

Obesity may lead to metabolic complications, such as insulin resistance, which can progress via impaired fasted glucose and impaired glucose tolerance to type 2 diabetes mellitus (T2DM) and to the development of micro- and macro-vascular complications.

Metformin, an oral anti-diabetic licensed for T2DM for adults and children from 10 years onwards, is already used off label in obese children and adolescents with insulin resistance, even though the specific effects of metformin in these obese children and adolescents have not been elucidated, particularly upon long-term use.

The rationale for this study is based on the hypothesis that metformin may reduce body mass index (BMI), insulin resistance and percentage of body-fat in obese children and adolescents with insulin resistance. Further more it is anticipated that metformin may delay the progression to T2DM and thereby micro- and macro-vascular complications in obese children and adolescents with insulin resistance.

Inclusion criteria

• Age ≥ 10 and ≤ 16 years at study entry
• Caucasian descent
• Obesity defined as BMI-SDS > 2.3
• Insulin resistance defined as HOMA-IR ≥ 3.4.
• An obtained informed consent from subjects and parents/caregivers.

Exclusion criteria

• Presence of T2DM (American Diabetes Association criteria)
• Presence of endocrine disorders with steroid therapy
• Suspicion of polycystic ovarium syndrome;
• Height < -1.3 SD of target height;
• Syndrome disorders with or without mental retardation;
• Use of anti-hyperglycaemic drugs;
• Pregnancy (pregnancy test will be performed, if applicable);
• (History of) alcohol abuse;
• Impaired renal and/or hepatic function (defined as GFR < 80 ml/min. GFR=40 x length (cm) / serumcreatinin (μmol/l and ALAT >150% of normal value for age);
• Use of ritonavir; use of ACE inhibitors;
• Insufficient knowledge of the Dutch language.