Carbohydrate intake and biomarkers of glycemic control among us adults: the third national health and nutrition examination survey (nhanes iii).

« BACKGROUND: Recommendations for preventing and treating type 2 diabetes include consuming carbohydrates, predominantly from whole grains, fruit, vegetables, and low-fat milk. However, the quantity and type of carbohydrates consumed may contribute to disorders of glycemic control. OBJECTIVE: We evaluated the association between carbohydrate intakes and biomarkers of glycemic control in a nationally representative sample of healthy US adults who participated in a cross-sectional study, the third National Health and Nutrition Examination Survey. DESIGN: The sample (5730 men and 6125 women aged > or = 20 y) was divided into quintiles of carbohydrate intake (as a percentage of energy). Carbohydrate intakes were examined in relation to glycated hemoglobin (Hb A(1c)), plasma glucose, serum C-peptide, and serum insulin concentrations by using logistic regression. RESULTS: Carbohydrate intakes were not associated with Hb A(1c), plasma glucose, or serum insulin concentrations in men or women after adjustment for confounding variables. Carbohydrate intakes were inversely associated with serum C-peptide concentrations in men and women. Odds ratios for elevated serum C-peptide concentrations for increasing quintiles of carbohydrate intake were 1.00, 0.88, 0.57, 0.39, and 0.75 (P for trend = 0.016) in men, and 1.00, 0.69, 0.57, 0.36, and 0.41 (P for trend = 0.007) in women. When carbohydrate intakes were further adjusted for intakes of total and added sugar, the association of serum C-peptide with carbohydrate intakes was strengthened in men. CONCLUSIONS: Carbohydrate intakes were not associated with Hb A(1c), plasma glucose, or serum insulin concentrations but were inversely associated with the risk of elevated serum C-peptide; this supports current recommendations regarding carbohydrate intake in healthy adults. »