This interesting study by Ladwa et al. examined the relationships between intrahepatic fat and insulin clearance, secretion, and sensitivity in 23 black Africans and 23 white Europeans.

The authors report lower insulin clearance in BA, as expected, which does not seem to be related to insulin resistance or hepatic fat. The manuscript is clear and data are well presented. Findings may have physiological and clinical relevance.

Strenghts of the study include the accurate metabolic characterization of study participants using multiple state-of-the-art techniques. My main concerns are related to the study population.

1. Negative findings may be explained by the small sample size and by the characteristics of study participants. Recruited BA show a narrow range of intrahepatic fat, which was below the pathological threshold of 5.5% (diagnostic for NAFL).

This may have hindered the chance to observe a linear correlation between intrahepatic fat and insulin clearance in BA, while it cannot be excluded that a relation between these two variables exists in more obese populations.

1. The statistics does not support the existence of ethnic differences in the relationship between insulin clearance and intrahepatic fat (p=0.837 for interaction). This evidence again may depend on the small sample size.

2. The increase in nutrient substrates and gut hormones after a meal is believed to be responsible for the postprandial decrease in hepatic insulin clearance. In the light of this observation, how does insulin clearance during the glucose clamp correlate with post-meal insulin clearance?

My comments have been adequately addressed