Dietary glycemic index and glycemic load, carbohydrate and fiber intake, and measures of insulin sensitivity, secretion, and adiposity in the Insulin Resistance Atherosclerosis Study.
OBJECTIVE
We studied the association of digestible carbohydrates, fiber intake, glycemic index, and glycemic load with insulin sensitivity (S(I)), fasting insulin, acute insulin response (AIR), disposition index, BMI, and waist circumference.


METHODS
Data on 979 adults with normal (67%) and impaired (33%) glucose tolerance from the Insulin Resistance Atherosclerosis Study (1992-1994) were analyzed. Usual dietary intake was assessed via a 114-item interviewer-administered food frequency questionnaire from which nutrient intakes were estimated. Published glycemic index values were assigned to food items and average dietary glycemic index and glycemic load calculated per subject. S(I) and AIR were determined by frequently sampled intravenous glucose tolerance test. Disposition index was calculated by multiplying S(I) with AIR. Multiple linear regression modeling was employed.


RESULTS
No association was observed between glycemic index and S(I), fasting insulin, AIR, disposition index, BMI, or waist circumference after adjustment for demographic characteristics or family history of diabetes, energy expenditure, and smoking. Associations observed for digestible carbohydrates and glycemic load, respectively, with S(I), insulin secretion, and adiposity (adjusted for demographics and main confounders) were entirely explained by energy intake. In contrast, fiber was associated positively with S(I) and disposition index and inversely with fasting insulin, BMI, and waist circumference but not with AIR.


CONCLUSIONS
Carbohydrates as reflected in glycemic index and glycemic load may not be related to measures of insulin sensitivity, insulin secretion, and adiposity. Fiber intake may not only have beneficial effects on insulin sensitivity and adiposity, but also on pancreatic functionality.
Liese
Angela D
AD
Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, 800 Sumter Street, Columbia, SC 29205, USA. liese@sc.edu
Schulz
Mandy
M
Fang
Fang
F
Wolever
Thomas M S
TM
D'Agostino
Ralph B
RB
Sparks
Karen C
KC
Mayer-Davis
Elizabeth J
EJ
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D050197:Atherosclerosis / Q000178:diet therapy*; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance / Q000178:diet therapy; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D008297:Male; D009747:Nutritional Physiological Phenomena; D012016:Reference Values; D012907:Smoking
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D007328:Insulin