Fructose, glycemic load, and quantity and quality of carbohydrate in relation to plasma C-peptide concentrations in US women

BACKGROUND: Circulating C-peptide concentrations are associated with insulin resistance and the development of type 2 diabetes. However, associations between fructose and the quantity and quality of total carbohydrate intake in relation to C-peptide concentrations have not been adequately examined. OBJECTIVE: We assessed the association of dietary fructose, glycemic load, and carbohydrate intake with fasting C-peptide concentrations. DESIGN: Plasma C-peptide concentrations were measured in a cross-sectional setting in 1999 healthy women from the Nurses' Health Study I and II. Dietary fructose, glycemic load, and carbohydrate intake were assessed with the use of semiquantitative food-frequency questionnaires. RESULTS: After multivariate adjustment, subjects in the highest quintile of energy-adjusted fructose intake had 13.9% higher C-peptide concentrations (P for trend = 0.01) than did subjects in the lowest quintile. Similarly, in the multivariate model, subjects in the highest quintile of glycemic load had 14.1% (P for trend = 0.09) and 16.1% (P for trend = 0.04) higher C-peptide concentrations than did subjects in the lowest quintile after further adjustment for total fat or carbohydrate intake, respectively. In contrast, subjects with high intakes of cereal fiber had 15.6% lower (P for trend = 0.03) C-peptide concentrations after control for other covariates. CONCLUSIONS: Our results suggest that high intakes of fructose and high glycemic foods are associated with higher C-peptide concentrations, whereas consumption of carbohydrates high in fiber, such as whole-grain foods, is associated with lower C-peptide concentrations. Furthermore, our study suggests that these nutrients play divergent roles in the development of insulin resistance and type 2 diabetes.     

Carbohydrate intake is associated with diet quality and risk factors for cardiovascular disease in U.S. adults: NHANES III

OBJECTIVES: To determine if carbohydrate intake, as a % of energy, was related to diet quality and risk factors for cardiovascular disease (CVD) in adults in a cross-sectional and population-based study in the U.S. METHODS: Data from the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994) were utilized. The nationally representative sample of the U.S. population (3,754 men, 4,074 women, ages 25 to 64 years) was divided into quintiles of carbohydrate intake (% of energy), which was examined in relation to risk factors for CVD: systolic blood pressure, body mass index (BMI), and concentrations of serum triglyceride, serum total and HDL cholesterol and plasma glucose. RESULTS: When covariates (age, ethnicity, smoking, alcohol intake and total energy intake) were adjusted in multivariate analyses, carbohydrate intakes (% of energy) were inversely associated with BMI and serum total cholesterol concentration in men and BMI in women and positively associated with serum triglyceride concentration in women. When total sugar intake (% of energy) was further controlled as a step to understand the quality of carbohydrate, carbohydrate intakes (% of energy) was a stronger predictor of BMI and plasma glucose in men and BMI in women. A high carbohydrate diet (>57.4% of energy in men and >59.1% of energy in women) was associated with a low serum HDL-cholesterol concentration in men and high serum triglyceride in women. CONCLUSION: Moderately high carbohydrate (50% to 55% of energy) diets were associated with low CVD risks with favorable lipid profiles.     

Carbohydrate Intake and Refined-Grain Consumption Are Associated with Metabolic Syndrome in the Korean Adult Population

BackgroundMetabolic syndrome is prevalent in the Asian population, but little is known about its associations with sources or types of dietary carbohydrates.ObjectiveWe examined relationships between metabolic syndrome prevalence and dietary carbohydrate intake, including total carbohydrate, energy from carbohydrates, dietary glycemic index, dietary glycemic load, total grains, refined grains, and white rice in Korean men and women.DesignThis cross-sectional study was based on data from the Fourth Korea National Health and Nutrition Examination Survey (KNHANES 2007-2009) and a nationally representative sample.Participants/settingA total of 6,845 adults (2,631 men, 4,214 women) aged 30 to 65 years with no diagnosed diabetes, hypertension, or dyslipidemia were selected. Dietary intake data were obtained using the 24-hour recall method and all dietary carbohydrate intakes were divided into quintiles by sex.Main outcome measuresMetabolic syndrome and its components were defined using the National Cholesterol Education Program Adult Treatment Panel III criteria.Statistical analyses performedAll statistical analyses accounted for the complex sampling design effect and used appropriate sample weights. Multivariate adjusted logistic regression was used to estimate odds ratios and 95% CIs for metabolic syndrome across quintiles of dietary carbohydrate intake.ResultsAfter controlling for potential confounding variables, the determinants of metabolic syndrome were the percentage of energy from carbohydrates in men and intakes of refined grains, including white rice, in women. Triglyceride, high-density lipoprotein cholesterol, and fasting blood glucose levels were associated with the percentage of energy from carbohydrates in men and white rice intake in women.ConclusionsOur findings suggest that the sources and types of carbohydrates were differentially associated with metabolic syndrome according to sex in the Korean adult population. The percentage of energy from carbohydrates in men and intake of refined grains, including white rice, in women were associated with metabolic syndrome.     

Carbohydrate intake, glycemic index, glycemic load, and risk of postmenopausal breast cancer in a prospective study of French women

BACKGROUND: Diets high in carbohydrates may result in chronically elevated insulin concentrations and may affect breast cancer risk by stimulation of insulin receptors or through insulin-like growth factor I (IGF-I)-mediated mitogenesis. Insulin response to carbohydrate intake is increased in insulin-resistant states such as obesity. OBJECTIVE: We sought to evaluate carbohydrate intake, glycemic index (GI), and glycemic load (GL) and subsequent overall and hormone-receptor-defined breast cancer risk among postmenopausal women. DESIGN: A prospective cohort analysis of dietary carbohydrate and fiber intakes was conducted among 62 739 postmenopausal women from the E3N French study who had completed a validated dietary history questionnaire in 1993. During a 9-y period, 1812 cases of pathology-confirmed breast cancer were documented through follow-up questionnaires. Nutrients were categorized into quartiles and energy-adjusted with the regression-residual method. Cox model-derived relative risks (RRs) were adjusted for known determinants in breast cancer. RESULTS: Dietary carbohydrate and fiber intakes were not associated with overall breast cancer risk. Among overweight women, we observed an association between GI and breast cancer (RR(Q1-Q4): 1.35; 95% CI: 1.00, 1.82; P for trend = 0.04). For women in the highest category of waist circumference, the RR(Q1-Q4) was 1.28 (95% CI: 0.98, 1.67; P for trend = 0.10) for carbohydrates, 1.35 (95% CI: 1.04, 1.75; P for trend = 0.01) for GI, and 1.37 (95% CI: 1.05, 1.77; P for trend = 0.003) for GL. We also observed a direct association between carbohydrate intake, GL, and estrogen receptor-negative breast cancer risk. CONCLUSIONS: Rapidly absorbed carbohydrates are associated with postmenopausal breast cancer risk among overweight women and women with large waist circumference. Carbohydrate intake may also be associated with estrogen receptor-negative breast cancer.     

Whole grains, bran, and germ in relation to homocysteine and markers of glycemic control, lipids, and inflammation 1

BACKGROUND: Intake of whole grains is inversely associated with risk of diabetes and ischemic heart disease in observational studies. The lower risk associated with high whole-grain intakes may be mediated through improvements in glycemic control, lipid profiles, or reduced inflammation. OBJECTIVE: The aim was to examine whether the intake of whole grains, bran, and germ is related to homocysteine, plasma markers of glycemic control (fasting insulin, hemoglobin A1c, C-peptide, and leptin), lipids (total cholesterol, triacylglycerol, HDL cholesterol, and LDL cholesterol), and inflammation (C-reactive protein, fibrinogen, and interleukin 6). DESIGN: This was a cross-sectional study of the relations of whole grains, bran, and germ intakes with homocysteine and markers of glycemic control, lipids, and inflammation in 938 healthy men and women. RESULTS: Whole-grain intake was inversely associated with homocysteine and markers of glycemic control. Compared with participants in the bottom quintile of whole-grain intake, participants in the highest quintile had 17%, 14%, 14%, and 11% lower concentrations of homocysteine (P < 0.01), insulin (P = 0.12), C-peptide (P = 0.03), and leptin (P = 0.03), respectively. Inverse associations were also observed with total cholesterol (P = 0.02), HDL cholesterol (P = 0.05), and LDL cholesterol (P = 0.10). Whole-grain intake was not associated with the markers of inflammation. Whole-grain intake was most strongly inversely associated with markers of glycemic control in this population. CONCLUSION: The results suggest a lower risk of diabetes and heart disease in persons who consume diets high in whole grains.     

Current Zinc Intake and Risk of Diabetes and Coronary Artery Disease and Factors Associated with Insulin Resistance in Rural and Urban Populations of North India

Objective: To determine the association between current zinc intake and prevalence of coronary artery disease (CAD) and diabetes as well as factors associated with insulin resistance.

Design, Subjects and Methods: In this cross sectional survey, 3575 subjects, aged 25 to 64 years, including 1769 rural (894 men, 875 women) and 1806 urban (904 men, 902 women) subjects were studied. The survey methods included questionnaires for 7-day food intake record, physical examination, and electrocardiography using World Health Organization criteria.

Results: The prevalence of CAD, diabetes and glucose intolerance was significantly higher among subjects consuming lower intakes of dietary zinc. There was a higher prevalence of hypertension, hypertriglyceridemia and low high-density lipoprotein cholesterol levels which showed significant upward trend with lower zinc intakes. Serum lipoprotein (a) and 2-hour plasma insulin levels also were associated with low zinc intake. Multivariate logistic regression analysis after adjustment for age showed that zinc intake and CAD were inversely associated. Serum zinc (odds ratio:men 0.77, women 0.57), serum triglycerides (men 0.86, women 0.81), blood pressure (0.83 men, women 0.76), diabetes mellitus (men 0.90, women 0.85), central obesity (men 0.88, women 0.87), glucose intolerance (men 0.66, women 0.57) and low high-density lipoprotein cholesterol (men 0.72, women 0.70) were significant risk factors for CAD (explained by tertiles of zinc status) in urban subjects. These associations were not observed in rural subjects.

Conclusion: Lower consumption of dietary zinc and low serum zinc levels were associated with an increased prevalence of CAD and diabetes and several of their associated risk factors including hypertension, hypertriglyceridemia and other factors suggestive of mild insulin resistance in urban subjects.     

Glycemic index,glycemic load,and risk of type 2 diabetes

The possibility that high, long-term intake of carbohydrates that are rapidly absorbed as glucose may increase the risk of type 2 diabetes has been a long-standing controversy. Two main mechanisms have been hypothesized, one mediated by increases in insulin resistance and the other by pancreatic exhaustion as a result of the increased demand for insulin. During the past decade, several lines of evidence have collectively provided strong support for a relation between such diets and diabetes incidence. In animals and in short-term human studies, a high intake of carbohydrates with a high glycemic index (a relative measure of the incremental glucose response per gram of carbohydrate) produced greater insulin resistance than did the intake of low-glycemic-index carbohydrates. In large prospective epidemiologic studies, both the glycemic index and the glycemic load (the glycemic index multiplied by the amount of carbohydrate) of the overall diet have been associated with a greater risk of type 2 diabetes in both men and women. Conversely, a higher intake of cereal fiber has been consistently associated with lower diabetes risk. In diabetic patients, evidence from medium-term studies suggests that replacing high-glycemic-index carbohydrates with a low-glycemic-index forms will improve glycemic control and, among persons treated with insulin, will reduce hypoglycemic episodes. These dietary changes, which can be made by replacing products made with white flour and potatoes with whole-grain, minimally refined cereal products, have also been associated with a lower risk of cardiovascular disease and can be an appropriate component of recommendations for an overall healthy diet.     

Phylloquinone intake, insulin sensitivity, and glycemic status in men and women

BACKGROUND: Limited evidence suggests that vitamin K may have a beneficial role in glucose homeostasis. No observational data exist on the associations between vitamin K intake and insulin sensitivity. OBJECTIVE: We aimed to examine associations between vitamin K intake and measures of insulin sensitivity and glycemic status in men and women aged 26-81 y. DESIGN: We assessed the cross-sectional associations of self-reported phylloquinone (vitamin K(1)) intake with insulin sensitivity and glycemic status in the Framingham Offspring Cohort. Dietary and supplemental phylloquinone intakes were assessed by using a food-frequency questionnaire. Insulin sensitivity was measured by fasting and 2-h post-oral-glucose-tolerance test (OGTT) insulin, the homeostasis model assessment of insulin resistance (HOMA-IR), and the insulin sensitivity index (ISI(0,120)). Glycemic status was assessed by fasting and 2-h post-OGTT glucose and glycated hemoglobin (HbA(1c)). RESULTS: Higher phylloquinone intake was associated with greater insulin sensitivity and glycemic status, as measured by 2-h post-OGTT insulin and glucose and ISI(0,120), after adjustment for age, sex, waist circumference, lifestyle characteristics, and diet quality [2-h post-OGTT insulin: lowest and highest quintile, 81.0 and 72.7 microU/mL, respectively (P for trend = 0.003); 2-h post-OGTT glucose: 106.3 and 101.9 mg/dL, respectively (P for trend = 0.009); ISI(0,120): 26.3 and 27.3 mg L(2)/mmol mU min (P for trend = 0.009)]. Phylloquinone intake was not associated with fasting insulin and glucose concentrations, HOMA-IR, or HbA(1c). CONCLUSION: Our findings support a potential beneficial role for phylloquinone in glucose homeostasis in men and women.     

High carbohydrate intake was inversely associated with high-density lipoprotein cholesterol among Korean adults

The traditional Asian diet, which is characterized as being high in carbohydrate with an abundance of vegetables, may be beneficial for preventing metabolic syndrome abnormalities within the Asian population. However, the prevalence of metabolic syndrome is increasing in Asian countries. This study explored the association between dietary carbohydrates and low high-density lipoprotein cholesterol (HDL-C) prevalence, one of the abnormalities of metabolic syndrome in Korean adults. We used the data from the Fourth Korea National Health and Nutrition Examination Survey and evaluated a total of 9947 Korean adults older 20 years. To measure carbohydrate quality and quantity, total carbohydrate intake (g/d), percentage of energy from carbohydrate, glycemic index, and glycemic load were divided into quintiles. Mean levels of HDL-C significantly decreased across the quintiles for all types of dietary carbohydrate intake except glycemic index after adjusting for potential variables in both men and women. Odds ratios for having low HDL-C in the highest quintile were 1.66 (95% confidence interval, 1.24-2.22) for total carbohydrate, 1.34 (1.02-1.75) for percentage of energy from carbohydrate, and 1.54 (1.17-2.03) for glycemic load in men as compared with the second quintile as a reference. Odds ratio for low HDL-C was 1.38 (1.12-1.71) for percentage of energy from carbohydrate in women. In conclusion, our study indicates that low HDL-C is associated with high carbohydrate intake without regard to energy or fat intake. Further studies would be necessary to optimize carbohydrate intake quantitatively on dyslipidemia for Asian population.     

Carbohydrates, dietary fiber, and incident type 2 diabetes in older women

BACKGROUND: Dietary carbohydrates may influence the development of type 2 (non-insulin-dependent) diabetes, for example, through effects on blood glucose and insulin concentrations. OBJECTIVE: We examined the relations of baseline intake of carbohydrates, dietary fiber, dietary magnesium, and carbohydrate-rich foods and the glycemic index with incidence of diabetes. DESIGN: This was a prospective cohort study of 35988 older Iowa women initially free of diabetes. During 6 y of follow-up, 1141 incident cases of diabetes were reported. RESULTS: Total grain, whole-grain, total dietary fiber, cereal fiber, and dietary magnesium intakes showed strong inverse associations with incidence of diabetes after adjustment for potential nondietary confounding variables. Multivariate-adjusted relative risks of diabetes were 1.0, 0.99, 0.98, 0.92, and 0.79 (P for trend: 0.0089) across quintiles of whole-grain intake; 1.0, 1.09, 1.00, 0.94, and 0.78 (P for trend: 0.005) across quintiles of total dietary fiber intake; and 1.0, 0.81, 0.82, 0.81, and 0.67 (P for trend: 0.0003) across quintiles of dietary magnesium intake. Intakes of total carbohydrates, refined grains, fruit and vegetables, and soluble fiber and the glycemic index were unrelated to diabetes risk. CONCLUSION: These data support a protective role for grains (particularly whole grains), cereal fiber, and dietary magnesium in the development of diabetes in older women.     

Dietary carbohydrate, glycemic index, and glycemic load in relation to risk of colorectal cancer in women

Diets with a high glycemic index and glycemic load have been hypothesized to be implicated in the etiology of colorectal cancer owing to their potential to increase postprandial glucose and insulin levels. Prospective data on glycemic index and glycemic load in relation to colorectal cancer risk are limited and inconsistent. Therefore, the authors prospectively investigated the associations of dietary carbohydrate, glycemic index, and glycemic load with the incidence of colorectal cancer among 61,433 Swedish women who were free of cancer in 1987-1990 and completed a 67-item food frequency questionnaire. During follow-up through June 2005, 870 incident cases of colorectal adenocarcinoma were diagnosed. Carbohydrate intake, glycemic index, and glycemic load were not associated with risk of colorectal cancer, colon cancer, or rectal cancer. The multivariate hazard ratios for colorectal cancer comparing the highest with the lowest quintile were 1.10 (95% confidence interval: 0.85, 1.44) for carbohydrate intake, 1.00 (95% confidence interval: 0.75, 1.33) for glycemic index, and 1.06 (95% confidence interval: 0.81, 1.39) for glycemic load. Results did not vary by body mass index. The findings from this prospective study do not support the hypothesis that a high carbohydrate intake, a high glycemic index, and a high glycemic load increase the risk of colorectal cancer.     

Dietary fiber intakes and insulin requirements in pregnant women with type 1 diabetes

OBJECTIVE: To determine whether higher dietary fiber intake (water soluble and insoluble) is associated with lower insulin requirements and better glycemic control in pregnant women with type 1 diabetes consuming a self-selected diet. DESIGN: A longitudinal, observational study. SUBJECTS: Pregnant women (n=141) with type 1 diabetes participating in an interdisciplinary program examining the effects of glycemic control on pregnancy outcome (Diabetes and Pregnancy Program, University of Cincinnati Medical Center). MEASUREMENTS: We determined total, water soluble and insoluble fiber intakes from 3-day food records kept each trimester during pregnancy. Outcome measures were insulin dose, pre-meal blood glucose, and glycated hemoglobin concentrations. STATISTICAL ANALYSES: Correlation coefficients, multiple regression, mixed-model analysis of variance. RESULTS: Mean intakes (g/day) of total, water soluble fiber, and insoluble fiber were 14.0 (range, 1.8-33.1), 4.8 (range, 0.6-10.5) and 9.0 (range, 1.1-24.0), respectively. In the second and third trimesters of pregnancy, insulin requirements were inversely associated with total, water soluble, and insoluble fiber intakes; the correlation coefficients ranged from -0.22 to -0.17 (P=.02 to .08). Insulin requirements associated with a higher fiber intake (20.5 g/day) were 16% to 18% lower than for a lower fiber intake (8.1 g/day). These relations remained after adjustment for body weight, disease severity and duration, insulin type, and study year in the second (P=.03 to .10) but not in the third trimester. Pre-meal blood glucose and glycated hemoglobin concentrations were not associated with fiber intake. CONCLUSIONS: Among pregnant women with type 1 diabetes, higher fiber intake is associated with lower daily insulin requirements. Dietary fiber intake should be considered when counseling patients about the management of blood glucose concentrations.     

A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women

BACKGROUND: Little is known about the effects of the amount and type of carbohydrates on risk of coronary heart disease (CHD). OBJECTIVE: The objective of this study was to prospectively evaluate the relations of the amount and type of carbohydrates with risk of CHD. DESIGN: A cohort of 75521 women aged 38-63 y with no previous diagnosis of diabetes mellitus, myocardial infarction, angina, stroke, or other cardiovascular diseases in 1984 was followed for 10 y. Each participant's dietary glycemic load was calculated as a function of glycemic index, carbohydrate content, and frequency of intake of individual foods reported on a validated food-frequency questionnaire at baseline. All dietary variables were updated in 1986 and 1990. RESULTS: During 10 y of follow-up (729472 person-years), 761 cases of CHD (208 fatal and 553 nonfatal) were documented. Dietary glycemic load was directly associated with risk of CHD after adjustment for age, smoking status, total energy intake, and other coronary disease risk factors. The relative risks from the lowest to highest quintiles of glycemic load were 1.00, 1.01, 1. 25, 1.51, and 1.98 (95% CI: 1.41, 2.77 for the highest quintile; P for trend < 0.0001). Carbohydrate classified by glycemic index, as opposed to its traditional classification as either simple or complex, was a better predictor of CHD risk. The association between dietary glycemic load and CHD risk was most evident among women with body weights above average ?ie, body mass index (in kg/m(2)) >/= 23. CONCLUSION: These epidemiologic data suggest that a high dietary glycemic load from refined carbohydrates increases the risk of CHD, independent of known coronary disease risk factors.     

Dietary carbohydrates and glycated proteins in the blood in non diabetic subjects

OBJECTIVES: To evaluate in non diabetic subjects the association of dietary carbohydrates with fructosamine, a measure of total non enzymatic glycated proteins in the blood associated with mortality, particularly from cardiovascular diseases. METHODS: A population sample of 252 subjects (137 men and 115 women, mean age 57) without diabetes and with fasting serum glucose <126 mg/100 mL, participated in the study. Diet and dietary glycemic load were measured with a validated food frequency questionnaire. Fructosamine was measured with a standard colorimetric method. Multiple linear regression was used to analyze the data. RESULTS: Serum fructosamine was positively associated with dietary glycemic load. Moreover, it was positively associated with intake of polyunsaturated fats and alcohol; and negatively with intake of monounsaturated fats, and with physical activity. CONCLUSION: The quality of carbohydrate and fat, as well as physical activity, may explain the variation of non enzymatic glycated serum proteins in non diabetic subjects.     

Carbohydrate, glycemic index, and glycemic load and colorectal adenomas in the Prostate, Lung, Colorectal, and Ovarian Screening Study

BACKGROUND: It is possible that high-glycemic-load diets, through their hyperinsulinemic effects, can increase the risk of colorectal cancer. OBJECTIVE: We analyzed data from a cancer screening study to determine whether persons with high-glycemic-load diets would be at an increased risk of distal adenomas. DESIGN: We included subjects with no prior adenoma or cancer from the Prostate, Lung, Colorectal, and Ovarian screening trial and whose results from flexible sigmoidoscopy exams indicated either no lesions (n = 34 817) or >/=1 distal adenoma (n = 3696). We used a 137-item food-frequency questionnaire to assess usual dietary intake over the preceding 12 mo. Using logistic regression analysis, we calculated, separately for men and women, prevalence odds ratios (ORs) and 95% CIs of sigmoidoscopy-detected, distal adenomas for quintiles of energy-adjusted dietary carbohydrate, glycemic index, and glycemic load. RESULTS: ORs decreased with increasing intakes of carbohydrate for both the men and the women in unadjusted models, but these associations were attenuated in multivariate-adjusted models. Among the men, the association remained significant after adjustment (OR: 0.71; 95% CI 0.60, 0.84; P for trend < 0.0001), but in the women it did not (OR: 0.89; 95% CI: 0.73, 1.10; P for trend = 0.30). The results for glycemic index showed no associations in either men or women. Results for glycemic load closely mirrored those for carbohydrate. CONCLUSION: Despite expectations that increasing glycemic load and glycemic index would increase the risk of adenoma, we observed no association in women and even an inverse association in men.     

Day-to-day consistency in amount and source of carbohydrate intake associated with improved blood glucose control in type 1 diabetes.

OBJECTIVE: To determine if a relationship exists between blood glucose control and variability in nutrient intake from day-to-day in subjects with type 1 diabetes. METHODS: Two three-day diet records and one measurement of glycated hemoglobin (HbA1c) were obtained from 272 subjects with type 1 diabetes treated with a mixture of regular and NPH insulins before breakfast and supper and using a standardized algorithm to adjust insulin dose according to the results of self-monitoring of blood glucose two to four times daily. Day-to-day variation in nutrient intake was expressed as the coefficient of variation (CV = SDx100/mean). RESULTS: Nutrient intakes in the study population (mean +/- SD) were energy 8.35+/-2.43 MJ, fat 81+/-30 g, protein 94+/-28 g, carbohydrate 227+/-68 g, starch 126+/-38 g and dietary fiber 20+/-6 g with diet glycemic index being 84.2+/-7.4. Neither energy, nutrient intakes nor insulin dose was significantly related to HbA1c. Day-to-day variation of carbohydrate (p = 0.0097) and starch (p = 0.0016) intakes and diet glycemic index (p = 0.033) was positively related to HbA1c, and the associations remained significant when adjusted for age, sex, duration of diabetes and BMI. Day-to-day variation in energy, protein or fat intakes was not related to HbA1c. CONCLUSIONS: Consistency in the amount and source of carbohydrate intake from day-to-day is associated with improved blood glucose control in people with type 1 diabetes, a result which supports continued educational efforts to achieve adherence to a diabetes diet plan. This conclusion may not apply to people on intensified insulin therapy who adjust their insulin dose based on their actual carbohydrate intake at each meal.     

Glycemic impact, glycemic glucose equivalents, glycemic index, and glycemic load: definitions, distinctions, and implications

Glycemic impact, defined as "the weight of glucose that would induce a glycemic response equivalent to that induced by a given amount of food" (American Association of Cereal Chemists Glycemic Carbohydrate Definition Committee, 2007), expresses relative glycemic potential in grams of glycemic glucose equivalents (GGEs) per specified amount of food. Therefore, GGE behaves as a food component, and (relative) glycemic impact (RGI) is the GGE intake responsible for a glycemic response. RGI differs from glycemic index (GI) because it refers to food and depends on food intake, whereas GI refers to carbohydrate and is a unitless index value unresponsive to food intake. Glycemic load (GL) is the theoretical cumulative exposure to glycemia over a period of time and is derived from GI as GI x carbohydrate intake. Contracted to a single intake of food, GL approximates RGI but cannot be accurately expressed in terms of glucose equivalents, because GI is measured by using equal carbohydrate intakes with usually unequal responses. RGI, on the other hand, is based on relative food and reference quantities required to give equal glycemic responses and so is accurately expressed as GGE. The properties of GGE allow it to be used as a virtual food component in food labeling and in food-composition databases linked to nutrition management systems to represent the glycemic impact of foods alongside nutrient intakes. GGE can also indicate carbohydrate quality when used to compare foods in equal carbohydrate food groupings.     

Glycemic load, glycemic index, and pancreatic cancer risk in the Netherlands Cohort Study

BACKGROUND: Recent studies of pancreatic cancer suggest a role for hyperinsulinemia in carcinogenesis. Because insulin is secreted in response to elevated blood glucose concentrations, dietary factors that increase these concentrations may be important in pancreatic carcinogenesis. OBJECTIVE: The objective was to examine prospectively the relation between pancreatic cancer risk and dietary glycemic load (GL), overall glycemic index (GI), and intake of total carbohydrates and mono- and disaccharides. DESIGN: The Netherlands Cohort Study consisted of 120,852 men and women who completed a baseline questionnaire in 1986. After 13.3 y of follow-up, 408 pancreatic cancer cases were detected, 66% of which were microscopically confirmed. A validated 150-item food-frequency questionnaire, completed at baseline, was used to calculate carbohydrate and mono- and disaccharide intakes and the GL and GI of the diet. RESULTS: Dietary GL, GI, or intake of carbohydrates and mono- and disaccharides were not associated with pancreatic cancer risk in this cohort. Also, the associations were not modified by sex. Our results did not change after the analysis was restricted to microscopically confirmed pancreatic cancer cases or after individuals who reported a history of diabetes at baseline were excluded from the analyses. CONCLUSIONS: Overall, our findings do not support the hypothesis that GL, GI, or intake of carbohydrates and mono- and disaccharides are positively associated with pancreatic cancer risk. This is in agreement with previous prospective studies that investigated the relation between GL and GI and pancreatic cancer risk.     

Nutrient and food intake in relation to serum leptin concentration among young Japanese women

OBJECTIVE: Little is known about the relation of modifiable dietary factors to circulating leptin concentrations, particularly in young adults and non-Western populations. We examined cross-sectional associations between nutrient and food intake and serum leptin concentration in young Japanese women. METHODS: Subjects were 424 female Japanese dietetic students 18-22 y of age. Intake of macronutrients (protein, total fat; saturated, monounsaturated, and polyunsaturated fatty acids; and carbohydrate), dietary fiber, and 12 food groups was assessed with a validated, self-administered, comprehensive, diet history questionnaire. Fasting blood samples were collected, and serum leptin concentrations were measured by radioimmunoassay. RESULTS: For nutrients, only dietary fiber was a significant determinant of serum leptin concentration. Increasing dietary fiber intake was associated with lower serum leptin concentration independent of potential confounding factors, including body mass index (mean serum leptin concentrations in the lowest and highest quintiles of dietary fiber intake were 8.6 and 7.5 ng/mL, respectively; P for trend = 0.026). Vegetables and pulses were the only foods significantly associated with serum leptin concentration, with higher intakes independently associated with lower concentrations (mean serum leptin concentrations in the lowest and highest quintiles of intake were 8.1 and 7.0 ng/mL, P for trend = 0.007, for vegetables and 8.8 and 7.6 ng/mL, P for trend = 0.019, for pulses, respectively). CONCLUSION: Intake of dietary fiber, vegetables, and pulses showed an independent inverse association with serum leptin concentration in a group of young Japanese women.     

The association of glycemic load and carbohydrate intake with colorectal cancer risk in the Multiethnic Cohort Study

BACKGROUND: High-glycemic-load diets may increase colorectal cancer risk through hyperinsulinemic effects. OBJECTIVE: We analyzed data for 191,004 participants in the Multiethnic Cohort Study to determine the risk of colorectal cancer associated with glycemic load (GL), carbohydrate, and sucrose and to ascertain whether this risk was modified by sex and ethnicity. DESIGN: During 8 y of follow-up, 2379 incident cases of colorectal adenocarcinoma occurred. We used baseline quantitative food-frequency questionnaire data to assess usual dietary intake over the preceding year. Using Cox regression, we calculated adjusted relative risks (RRs) and 95% CIs for colorectal cancer associated with quintiles of GL, carbohydrate, and sucrose. RESULTS: For both men and women in this cohort, white rice was the major contributor to GL. In multivariate models, RRs for colorectal cancer decreased significantly with increasing GL in women (RR for the highest quintile versus the lowest: 0.75; 95% CI: 0.57, 0.97; P for trend = 0.02) but not in men (RR: 1.15; 95% CI: 0.89, 1.48; P for trend = 0.19). Results for carbohydrate and sucrose were similar. The inverse association with GL was found in women of all ethnic groups (P for interaction = 0.58). In men, an interaction was found between ethnicity and GL (P < 0.01): white men had a positive association with increasing GL (RR: 1.69; 95% CI: 0.98, 2.92; P for trend < 0.01), but men of other ethnic groups did not. CONCLUSION: GL and carbohydrate intake appear to protect against colorectal cancer in women in the Multiethnic Cohort, perhaps because a major source of GL is white rice.