Introduction. The accumulation of components of the metabolic syndrome (MetS) is associated with a disturbed glucose metabolism in obese children. Aim of study. The aim of the present study was to evaluate the association between MetS and estimates of insulin sensitivity and β-cell function obtained from oral glucose tolerance test (OGTT)-derived indices in lean and obese children. Material and methods. A 2-hour OGTT was administered in 83 children aged 7-17 years. 47 children were obese and recruited from  a childhood obesity clinic and 36 were lean age- and sex-matched controls. Surrogate measures of insulin sensitivity and β-cell function were assessed by the OGTT-derived indices: the Matsuda index, the insulinogenic index, and the oral disposition index. The severity of MetS was assessed by measures of waist circumference, blood pressure, and fasting levels of triglycerides, high-density lipoprotein cholesterol, and glucose. Results. The 83 children were allocated to one of three groups according to the number of components of MetS: the median body mass index standard deviation score was 0.2 (range -0.6-2.9) in the low MetS risk group (n=36), 2.8 (0.1-4.1) in the high MetS risk group (n=25), and 2.9 (2.1-4.4) in the MetS group (n=22). An increasing number of MetS components were associated with a lower insulin sensitivity and an altered β-cell function according to the Matsuda index (p<0.0001), the insulinogenic index (p<0.0001), and the oral disposition index (p=0.005). Conclusions. Children burdened by the accumulation of components of MetS exhibited a disturbed glucose metabolism as expressed by lowered peripheral insulin sensitivity and β-cell function.