2.1. Subjects

Obese children requiring an OGTT to assess their carbohydrate metabolism were recruited at our Pediatric Endocrinology Unit (n = 24) in Puerta del Mar University Hospital, Cádiz, Spain. Nonobese children who needed a blood test (generally for preanesthesia), were recruited as control group (n = 15). All of them were prepubertal children, between 6 and 10 years of age.

Inclusion criteria for the obese group were children between 6 and 10 years in a tanner stage I with a BMI > +2 SD and, as mentioned above, with a medical prescription of an OGTT. On the other hand, the control group had a BMI < +2 SD and, as the obese group, an age between 6 and 10 years and Tanner I. We subdivided the obese group according to the result of the OGTT and their basal glucose and insulin levels. Patients were classified into the ObIR− group when they showed no evidence of carbohydrate metabolic impairment and into the ObIR+ group when presenting at least one of the following criteria: Impaired fasting glucose (IFG), impaired glucose tolerance (IGT) or insulin resistance (IR), according to the ADA criteria (a homeostasis model assessment of insulin resistance (HOMA-IR) score above 3.5, or fasting insulin > 15 µUI/mL, insulin at 120 min of OGTT > 75 µUI/mL or insulin at any time point of the curve > 150 µUI/mL [23]). Every OGTT was performed by a trained nurse in the clinic, after overnight fasting, with 1.75 g/kg (maximum 75 g) of sucrose (GlycoSull, QCA S.A., Tarragona, Spain). The control group was not subjected to the OGTT.