Are ethnic differences in insulin sensitivity explained by variation in carbohydrate intake?

Minority populations are disproportionately affected by diabetes. This health disparity may be due to less healthy diets and/or heritable factors in minority populations. These factors must be assessed concurrently to better appreciate their contribution to insulin sensitivity.

We analysed overweight, healthy adults using the National Health and Nutrition Examination Survey 1999-2000. Means for dietary intake variables and insulin sensitivity were calculated by ethnicity. Linear regressions were performed to evaluate the association between ethnicity, dietary variables, dietary glycaemic index and insulin sensitivity. Fasting insulin was used to characterise insulin sensitivity.

Non-Hispanic whites have higher energy and fat intake, while Hispanics have higher carbohydrate intake and African-Americans have lower fibre intake. In unadjusted analyses both Hispanics and African-Americans have lower insulin sensitivity, but only Hispanics are more likely to have lower insulin sensitivity after controlling for dietary variables and BMI.

Ethnic differences in insulin sensitivity remain after controlling for dietary differences and other factors, suggesting that inherent metabolic differences exist. Further studies are needed to define inherent metabolic factors, as well as other non-dietary factors that affect insulin sensitivity.