Can the Insulin Sensitivity Index (ISI) in Association with Insulin-like Growth Factor Binding Protein-1 Identify Insulin Resistance Early in Overweight Children?

Association between insulin resistance (IR) and non-alcoholic fatty liver disease (NAFLD) has been reported. This prompted us to evaluate the power of the insulin sensitivity index (ISI) in association with IGFBP-1 to identify IR early in obese children/adolescents. OGTT was performed in 34 obese/overweight children/adolescents. Glucose, insulin and IGFBP-1 were measured in serum samples and ISI was calculated. Considering the presence of three or more risk factors for IR as a criterion for IR, ISI < 4.6 showed 87.5% sensitivity and 94.5% specificity in diagnosing IR. IGFBP-1 was lower in the group with ISI < 4.6 (p < 0.01). In this group, three patients had higher than expected IGFBP-1, suggesting hepatic IR, while three patients with ISI > 4.6 showed very low IGFBP-1 levels. ISI < 4.6 is a good indicator of early peripheral IR and, associated with IGFBP-1, can identify increased risk of hepatic IR. Low IGFBP-1 levels among non-IR children may indicate increased portal insulin levels.