Glycemic index and serum high-density lipoprotein cholesterol concentration among US adults

Background: Dietary glycemic index, an indicator of the ability of the carb ohydrate to raise blood glucose levels, and glycemic load, the product of g lycemic index and carbohydrate intake, have been positively related to risk of coronary heart disease. However, the relationships between glycemic ind ex and glycemic load and high-density lipoprotein cholesterol (HDL-C) conce ntration in the US population are unknown. Methods: Using data from 13 907 participants aged 20 years and older in the Third National Health and Nutrition Examination Survey (1988-1994), we exa mined the relationships between glycemic index and glycemic load, which wer e determined from a food frequency questionnaire and HDL-C concentration. Results: The age-adjusted mean HDL-C concentrations for increasing quintile s of glycemic index distribution were 1.38, 1.32, 1.30, 1.26, and 1.27 mmol /L (P<.001 for trend). (To convert millimoles per liter to milligrams per d eciliter, divide by 0.0259.) After additional adjustment for sex, ethnicity , education, smoking status, body mass index, alcohol intake, physical acti vity, energy fraction from carbohydrates and fat, and total energy intake, the mean HDL-C concentrations for ascending quintiles of glycemic index wer e 1.36, 1.31, 1.30, 1.27, and 1.28 mmol/L (P<.001 for trend). Adjusting for the same covariates and considering glycemic index as a continuous variabl e, we found a change in HDL-C concentration of -0.06 mmol/L per 15-unit inc rease in glycemic index (P<.001). The multiple R-2 for the model was 0.23. Similarly, the multivariate-adjusted mean HDL-C concentrations for ascendin g quintiles of glycemic load distribution were 1.35, 1.31, 1.31, 1.30, and 1.26 mmol/L (P<.001 for linear trend). The inverse relationships between gl ycemic index and glycemic load and HDL-C persisted across all subgroups of participants categorized by sex or body mass index. Conclusions: These findings from a nationally representative sample of US a dults suggest that high dietary glycemic index and high glycemic load are a ssociated with a lower concentration of plasma HDL-C.