Characterization of β-cell function and insulin resistance in overweight Chinese adolescents with normal glucose...

This study aimed to investigate the characteristics of insulin resistance and β-cell secretion in healthy adolescents. A total of 124 adolescents with normal glucose tolerance (NGT) were divided according to BMI into normal weight (n=31; control), overweight (n=52) and obese (n=41) groups. Oral glucose tolerance tests were performed, and blood glucose (G₀, G₃₀ and G₁₂₀) and insulin (I₀, I₃₀ and I₁₂₀) levels at 0, 30 and 120 min, respectively, were measured. The homeostasis model assessment estimate of insulin resistance (HOMA-IR) and early insulin release index (IRI) were calculated to evaluate insulin sensitivity and early β-cell secretion. The G₀, G₁₂₀ levels and the natural logarithm (Ln) of I₃₀ and ΔI₃₀/ΔG₃₀ were similar in the overweight and obese groups, but significantly higher compared with those of the normal weight group (P<0.05). LnI₀ and LnHOMA-IR progressively increased (P<0.01) in correlation with the degree of obesity among the three groups. LnΔI₃₀/ΔG₃₀ and LnHOMA-IR were significantly positively correlated with the indices of obesity (P<0.001 and P<0.05, respectively). LnHOMA-IR was also positively correlated with the insulin levels at 30 and 120 min (r=0.454 and 0.314, respectively; P<0.001). In healthy adolescents, insulin resistance progressively increased with increased body mass index (BMI), but the compensatory increase in early insulin secretion was limited.