Metabolic Differences among Children of Different Ethnicities Are Magnified when Hepatic Insulin Extraction Is Included

Disposition index (DI) combines insulin sensitivity (S_I) and beta-cell function (acute insulin response AIRg), and is a predictor of type 2 diabetes (T2DM). Insulin clearance, an important factor in glucose metabolism, is not included, yet can vary among ethnic groups. Our aim is to examine the differences among the DI in different ethnicities, and group subjects considering not only S_I and AIRg, but also fractional hepatic insulin extraction (FE_L). We used data from 203 normal glucose tolerant children that underwent FSIGT [55 African American (AA), 88 European American (EA), 60 Hispanic American (HA), ages 7-13 years, mean BMI = 19 kg/m², basal glucose = 99 mg/dL, insulin = 78 pM, C-peptide = 511 pM]. Recent studies proved that HA and AA adults have an increased risk of developing T2DM. However, such studies are of interest for children of different ethnicities. The three DI hyperbolas, associated with ethnic groups (Figure 1A), are similar to each other. In contrast, cluster analysis also including FE_L (Figure 1B), reveals that in these children 3 different clusters exist, (silouhette values > 0.6 in 63% of subjects in cluster 1, 87% in cluster 2, and 95% in cluster 3), and they do not necessarily coincide with ethnicity. Thus, FE_L differs among children and it needs to be considered, together with S_I and AIRg, in order to clarify diabetes risk among children of different ethnicities.