Liver fat has a stronger association with risk factors for type 2 diabetes in African-American compared with Hispanic adolescents.

Abstract

Although overweight and obese African-Americans (AAs) have less visceral adipose tissue (VAT) and liver fat (LF) than Hispanics, they have a similar risk for type 2 diabetes. We examined ethnic differences in the association between VAT and LF with risk factors for type 2 diabetes to help explain this paradox. We conducted a cross-sectional study in an academic pediatric care facility. Subjects were overweight and obese AA (n = 131; 15.5 ± 3.3 years old) and Hispanic adolescents (n = 227; 14.7 ± 3.0 years old). Outcome measures included insulin sensitivity (SI), acute insulin response (AIR), and disposition index (DI) by frequently sampled i.v. glucose tolerance test and minimal modeling. LF, not VAT, was inversely associated with SI, and the effect of high LF compared with low was more pronounced in AAs (P(interaction) < .05). In Hispanics, high LF was associated with a 24% lower SI (P < .01) and a 31% increase in AIR (P < .01) and was not associated with DI (P = .35). In AAs, high LF was associated with a 49% lower SI (P < .001), was not associated with an increase in AIR (P = .25), and was associated with a 42% lower DI (P < .01), indicating failure of compensatory insulin secretion/clearance in response to insulin resistance. Prediabetes changed the relationship between high/low LF and DI in Hispanics (P(interaction) = .002) but not AAs such that prediabetic Hispanics with high LF had a 43% lower DI (P = .03) with no difference in those without prediabetes (P = .06). LF has a stronger effect on SI compared with VAT. Our results suggest that the impact of high LF on poor β-cell compensation is more pronounced in AAs. In Hispanics, the combination of high LF and prediabetes contributes to poor β-cell compensation.