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

Abstract

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.

Figure 1

Correlations of hepatic proton density fat fraction (hepatic PDFF) with insulin resistance (IR) in non-obese girls. No correlation was observed between the HFF and IR in non-Hispanic White (NHW) girls. Solid regression line is for Hispanic and dotted regression line is for NHW girls. Hepatic PDFF ≥5.56% consistent with hepatic steatosis