Ethnic differences in the effects of hepatic fat deposition on insulin resistance in nonobese middle school girls

Objective In nonobese youth, to investigate whether hepatic fat deposition and its metabolic consequences vary between ethnic groups. Design and Methods Thirty-two nonobese girls (12 Hispanic White [H] and 20 non-Hispanic White [NHW] girls), aged 11-14 years old were recruited. Outcome measures were MRI measured hepatic proton density fat fraction (hepatic PDFF), BMI Z-score, waist circumference, fasting insulin, glucose, adiponectin, sex hormone-binding globulin [SHBG], ALT, AST, triglycerides, and HOMA-IR. Results There were no significant differences in mean BMI Z-scores (P=0.546) or hepatic PDFF (P=0.275) between H and NHW girls; however, H girls showed significant correlations between hepatic PDFF and markers of IR (fasting insulin, HOMA-IR, adiponectin, SHBG, triglycerides; all P<0.05), while NHW girls showed no significant correlations. Matched by hepatic PDFF or BMI Z-score, H girls had more evidence of IR for a given hepatic PDFF (mean insulin, HOMA-IR, and SHBG; all P<0.05) or BMI Z-score (mean insulin and HOMA-IR; all P<0.01) than NHW girls. Conclusions In nonobese female youth, ethnicity-related differences in effects of hepatic fat on IR are evident, so that in H girls, a given amount of hepatic fat appears to result in a more predictable and greater degree of IR than in NHW girls.