Dietary fiber intake and glycemic index and incidence of diabetes in African-American and white adults: the ARIC study

OBJECTIVE: To determine the association of dietary fiber and glycemic index with incident type 2 diabetes in African-Americans and whites. RESEARCH DESIGN AND METHODS: We studied 12,251 adults aged 45-64 years and free of diabetes at baseline (1987-1989). A total of 1,447 cases of diabetes were reported between baseline and 9 years of follow-up. Diabetes status was determined by fasting glucose level > or =126 mg/dl (7.0 mmol/l), nonfasting glucose level > or =200 mg/dl (11.1 mmol/l), self-report of physician diagnosis, or use of diabetes medication. Usual dietary intake over the previous year was obtained at baseline using a 66-item food-frequency questionnaire. Nutrients were energy-adjusted using the residuals method. Proportional hazard regression analysis was used to examine dietary fiber intake and glycemic index as predictors of type 2 diabetes in both ethnic groups. RESULTS: After adjustment for age, BMI, education, smoking status, physical activity, sex, and field center, there were no statistically significant associations of intake of total dietary fiber, fruit fiber, legume fiber, glycemic index, or glycemic load with incident diabetes. The hazard ratio for the fifth compared with the first quintile of cereal fiber was 0.75 (95% CI 0.60-0.92) in whites and 0.86 (0.65-1.15) in African-Americans. CONCLUSIONS: This finding supports a protective role for cereal fiber in the development of diabetes in whites. More studies are needed to determine the role of dietary fiber and glycemic index in diabetes in African-Americans.     

Cereal fiber improves whole-body insulin sensitivity in overweight and obese women

OBJECTIVE: Cereal fiber intake is linked to reduced risk of type 2 diabetes in epidemiological observations. The pathogenic background of this phenomenon is unknown. Based on recent findings, we hypothesized that intake of purified insoluble oat fiber may improve whole-body insulin sensitivity. RESEARCH DESIGN AND METHODS: A randomized, controlled, single-blind, cross-over study was performed, and 17 overweight or obese subjects with normal glucose metabolism were analyzed. After consumption of nine macronutrient-matched portions of fiber-enriched bread (white bread enriched with 31.2 g insoluble fiber/day) or control (white bread) over a time period of 72 h, whole-body insulin sensitivity was assessed by euglycemic-hyperinsulinemic clamp. Energy intake was individually adjusted by providing standardized liquid meals. Hydrogen breath tests were performed to control for dietary adherence. RESULTS: When analyzing the entire cohort, whole-body glucose disposal was improved after fiber consumption (M value 6.56 +/- 0.32 vs. 6.07 +/- 0.27 mg . min(-1) . kg(-1); P = 0.043). Thirteen subjects had increased hydrogen breath test concentrations after fiber consumption, indicating probable dietary adherence. Restricting analysis to these subjects, improvements in M value (6.85 +/- 0.34 vs. 6.06 +/- 0.32 mg . min(-1) . kg(-1); P = 0.003) and insulin sensitivity, expressed as M/I ratio (M value divided by mean serum insulin at steady state: 3.73 +/- 0.23 vs. 3.21 +/- 0.27; P = 0.02), after fiber consumption were more pronounced. Plasma lipids, serum magnesium, ghrelin, and adiponectin concentrations, as well as substrate utilization and body weight, were not significantly changed by fiber intake (P > 0.15). CONCLUSIONS: Increased insoluble dietary fiber intake for 3 days significantly improved whole-body insulin sensitivity. These data suggest a potential mechanism linking cereal fiber intake and reduced risk of type 2 diabetes.     

A cross-sectional study of alcohol consumption patterns and biologic markers of glycemic control among 459 women

OBJECTIVE: Little research has explored associations of drinking patterns with glycemic control, especially among women. Our objective was to determine the relationship of patterns of alcohol consumption-including average daily consumption, weekly frequency of consumption, drinking with meals, and beverage type-with biologic markers of insulin resistance in young women. RESEARCH DESIGN AND METHODS: This study was cross-sectional in design. The subjects consisted of a stratified random subpopulation of 459 U.S. normal-weight and overweight female nurses, 33-50 years of age, drawn from the Nurses' Health Study II and sampled for distinct drinking patterns. Women provided blood samples and detailed information on dietary and lifestyle factors between 1995 and 1999. The main outcome measures were fasting insulin, C-peptide, and HbA(1c). RESULTS: Adjusting for age, smoking, physical activity, television watching, BMI, and several dietary factors, average alcohol intake was inversely associated with HbA(1c) (units in percentage of HbA(1c)): 0 g/day (reference = 5.36%), 0.1 to <5.0 g/day (-0.04%), 5.0 to <15.0 g/day (-0.09%), 15.0 to <25.0 g/day (-0.10%), and > or =25.0 g/day (-0.17%) (P value, test for trend <0.001). We found an inverse association of alcohol intake and insulin, but only for women with a BMI > or =25 kg/m(2). Specifically, insulin levels were lowest for episodic drinkers consuming > or =2 drinks per day on 0-3 days per week. Consumption with meals and type of alcoholic beverage did not further influence these results. CONCLUSIONS: Moderate alcohol consumption of 1-2 drinks per day on a few to several days of the week may have a beneficial glycemic effect, particularly among overweight women.     

Insulinemic and Inflammatory Dietary Patterns Show Enhanced Predictive Potential for Type 2 Diabetes Risk in Postmenopausal Women

OBJECTIVEThe empirical dietary index for hyperinsulinemia (EDIH) and empirical dietary inflammatory pattern (EDIP) scores assess the insulinemic and inflammatory potentials of habitual dietary patterns, irrespective of the macronutrient content, and are based on plasma insulin response or inflammatory biomarkers, respectively. The glycemic index (GI) and glycemic load (GL) assess postprandial glycemic potential based on dietary carbohydrate content. We tested the hypothesis that dietary patterns promoting hyperinsulinemia, chronic inflammation, or hyperglycemia may influence type 2 diabetes risk.RESEARCH DESIGN AND METHODSWe calculated dietary scores from baseline (1993–1998) food frequency questionnaires among 73,495 postmenopausal women in the Women’s Health Initiative, followed through March 2019. We used multivariable-adjusted Cox regression to estimate hazard ratios (HRs) and 95% CIs for type 2 diabetes risk. We also estimated multivariable-adjusted absolute risk of type 2 diabetes.RESULTSDuring a median 13.3 years of follow-up, 11,009 incident cases of type 2 diabetes were diagnosed. Participants consuming the most hyperinsulinemic or proinflammatory dietary patterns experienced greater risk of type 2 diabetes; HRs (95% CI) comparing highest to lowest dietary index quintiles were EDIH 1.49 (1.32–1.68; P_trend < 0.0001) and EDIP 1.45 (1.29–1.63; P_trend < 0.0001). The absolute excess incidence for the same comparison was 220 (EDIH) and 271 (EDIP) cases per 100,000 person-years. GI and GL were not associated with type 2 diabetes risk: GI 0.99 (0.88–1.12; P_trend = 0.46) and GL 1.01 (0.89–1.16; P_trend = 0.30).CONCLUSIONSOur findings in this diverse cohort of postmenopausal women suggest that lowering the insulinemic and inflammatory potentials of the diet may be more effective in preventing type 2 diabetes than focusing on glycemic foods.     

Higher intakes of fish protein are related to a lower risk of microalbuminuria in young Swedish type 1 diabetic patients

OBJECTIVE: To examine the influence of dietary intake from various protein and fat sources on the occurrence of microalbuminuria in type 1 diabetic patients. RESEARCH DESIGN AND METHODS: In this nested case control study, 1,150 patients with diabetes duration >5 years reported dietary habits for the previous 12 months and submitted urinary samples for the analysis of albumin excretion rate (AER). A total of 75 cases of albuminuria (overnight AER > or = 15 microg/min) were identified and compared with 225 duration-matched control subjects. RESULTS: Neither mean protein, fat intake, average fish protein intake (control subjects 4.56 +/- 3.83 g/day and cases 3.82 +/- 2.87 g/day; P = 0.12), nor intake of meat and vegetable protein differed between the cases of albuminuria and the control subjects. High consumers of fish protein (greater than the 75th percentile) (12 cases and 63 control subjects, mean intake 9.35 g fish protein/day, i.e., approximately 53 g fish/day) had lower odds ratios (ORs) for microalbuminuria than individuals consuming less fish protein (mean 2.72 g/day) (crude OR 0.49 and 95% CI 0.25-0.97). When adjusted for known confounding factors, such as HbA1c, mean arterial pressure, diabetes duration, age, sex, smoking, BMI, country region, and total energy, individuals with a high intake of fish protein and fish fat showed a reduction in the risk for microalbuminuria (OR 0.22 and 0.31, respectively; 95% CI 0.09-0.56 and 0.13-0.76, respectively). When fish protein and fat were adjusted for each other, a high intake of fish protein but not of fish fat was still significantly associated with a decrease in the risk for microalbuminuria. CONCLUSIONS: Total protein and fat intake were not associated with the presence of microalbuminuria, but a diet including a high amount of fish protein seemed to lessen the risk.     

The dietary treatment of diabetes mellitus

The most important dietary goal for individuals with type I diabetes mellitus is the establishment of a regular meal pattern with consistent day-to-day caloric and carbohydrate intake. Ideally, the diet should contain 55 to 60 per cent of total calories as carbohydrate, less than 30 per cent of calories as fat, less than 10 per cent of calories as saturated fat, and less than 300 mg of cholesterol per day. The best tool for helping type I individuals achieve these objectives is the Exchange Lists for Meal Planning. A second important dietary goal in type I diabetes is to avoid weight gain during intensive treatment programs. The most important dietary and therapeutic goal in obese persons with type II diabetes is weight loss. Unfortunately, no dietary method, whether initiated by self-help groups like TOPS, physicians, or other health care professionals, has been demonstrated to be effective in achieving and maintaining weight loss. Nevertheless, some individual patients will be successful, and it therefore is appropriate to attempt weight reduction with a balanced diet moderately restricted in calories. A reduction of 500 calories per day below the weight maintenance level is reasonable and can be expected to produce weight loss of about 1 lb per week. For those type II diabetic patients who are not able to lose weight and are at least twice their ideal body weight, gastric reduction surgery could be considered. The Glycemic Index of Foods is a new concept that has not been evaluated adequately. Recent evidence suggests that differences among foods are reduced when the foods are combined in a meal and thus raises questions about the utility of glycemic indexing. The longstanding restriction on the use of sucrose in the diabetic diet is without scientific basis. Recognizing this, the American Diabetes Association recently sanctioned consumption of modest amounts of sucrose in the diabetic diet. Although conclusive evidence is not yet available that high fiber diets improve glycemic control or reduce serum lipids in diabetic persons, it appears reasonable to encourage the consumption of natural foods high in soluble fiber. Vegetables (particularly legumes), oats, and many fruits are good sources. The American Diabetes Association recommends a goal of 40 g of soluble fiber intake per day. The dietary treatment of diabetes is likely to be more successful if physicians learn more about its essential features and pay it greater attention. The goals of dietary therapy are difficult to achieve and often require significant sacrifices.(ABSTRACT TRUNCATED AT 400 WORDS)     

Mealtime interactions relate to dietary adherence and glycemic control in young children with type 1 diabetes

OBJECTIVE: This study examined the relationships between parent-child mealtime interactions and dietary adherence and glycemic control in young children with type 1 diabetes. It was hypothesized that young children who exhibited disruptive mealtime behaviors would have more dietary deviations (poorer dietary adherence) and poor glycemic control. It was also hypothesized that parents of young children who used ineffective/coercive parenting strategies at mealtimes would have children with more dietary deviations and poor glycemic control. RESEARCH DESIGN AND METHODS: A total of 35 families of children (aged 2.2-7.9 years) with type 1 diabetes were recruited from a pediatric hospital. Families had at least three meals videotaped in their home, which were coded for parent, child, and eating behaviors, using the Dyadic Interaction Nomenclature for Eating. Children's dietary adherence was assessed according to deviations from the prescribed number of carbohydrate units per meal. Children's average glycemic excursion was assessed prospectively for 2 weeks, using a standardized home blood glucose meter. RESULTS: Findings demonstrated significant positive relationships between children's mealtime behavior, dietary deviations, and glycemic control. An examination of parent behaviors revealed significant positive correlations between parents' use of ineffective/coercive parenting strategies and children's dietary deviations and glycemic control. CONCLUSIONS: This was the first study to examine the relationship between parent-child mealtime interactions and health outcomes in young children with type 1 diabetes. The mealtime problems examined can be improved through specific behavioral interventions. Future research is needed to examine how parent-child interactions at mealtimes relate to children's health outcomes to inform clinical care.     

The effect of flexible low glycemic index dietary advice versus measured carbohydrate exchange diets on glycemic control in children with type 1 diabetes.

OBJECTIVE: To determine the long-term effect of low glycemic index dietary advice on metabolic control and quality of life in children with type 1 diabetes. RESEARCH DESIGN AND METHODS: Children with type 1 diabetes (n = 104) were recruited to a prospective, stratified, randomized, parallel study to examine the effects of a measured carbohydrate exchange (CHOx) diet versus a more flexible low-glycemic index (GI) dietary regimen on HbA(1c) levels, incidence of hypo- and hyperglycemia, insulin dose, dietary intake, and measures of quality of life over 12 months. RESULTS: At 12 months, children in the low-GI group had significantly better HbA(1c) levels than those in the CHOx group (8.05 +/- 0.95 vs. 8.61 +/- 1.37%, P = 0.05). Rates of excessive hyperglycemia (>15 episodes per month) were significantly lower in the low-GI group (35 vs. 66%, P = 0.006). There were no differences in insulin dose, hypoglycemic episodes, or dietary composition. The low-GI dietary regimen was associated with better quality of life for both children and parents. CONCLUSIONS: Flexible dietary instruction based on the food pyramid with an emphasis of low-GI foods improves HbA(1c) levels without increasing the risk of hypoglycemia and enhances the quality of life in children with diabetes.     

Beneficial effects of soy phytoestrogen intake in postmenopausal women with type 2 diabetes

OBJECTIVE: Phytoestrogen consumption has been shown to reduce risk factors for cardiovascular disease. Type 2 diabetes confers an adverse cardiovascular risk profile particularly in women after menopause. The aim of this study was to determine whether a dietary supplement with soy protein and isoflavones affected insulin resistance, glycemic control, and cardiovascular risk markers in postmenopausal women with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 32 postmenopausal women with diet-controlled type 2 diabetes completed a randomized, double blind, cross-over trial of dietary supplementation with phytoestrogens (soy protein 30 g/day, isoflavones 132 mg/day) versus placebo (cellulose 30 g/day) for 12 weeks, separated by a 2-week washout period. RESULTS: Compliance with the dietary supplementation was >90% for both treatment phases. When compared with the mean percentage change from baseline seen after 12 weeks of placebo, phytoestrogen supplementation demonstrated significantly lower mean values for fasting insulin (mean +/- SD 8.09 +/- 21.9%, P = 0.006), insulin resistance (6.47 +/- 27.7%, P = 0.003), HbA(1c) (0.64 +/- 3.19%, P = 0.048), total cholesterol (4.07 +/- 8.13%, P = 0.004), LDL cholesterol (7.09 +/- 12.7%, P = 0.001), cholesterol/HDL cholesterol ratio (3.89 +/- 11.7%, P = 0.015), and free thyroxine (2.50 +/- 8.47%, P = 0.004). No significant change occurred in HDL cholesterol, triglycerides, weight, blood pressure, creatinine, dehydroepiandrosterone sulfate, androstenedione, and the hypothalamic-pituitary-ovarian axis hormones. CONCLUSIONS: These results show that dietary supplementation with soy phytoestrogens favorably alters insulin resistance, glycemic control, and serum lipoproteins in postmenopausal women with type 2 diabetes, thereby improving their cardiovascular risk profile.     

Teaching subjects with type 2 diabetes how to incorporate sugar choices into their daily meal plan promotes dietary compliance and does not deteriorate metabolic profile

OBJECTIVE: To determine whether teaching free-living subjects with type 2 diabetes how to incorporate added sugars or sweets into their daily meal plan results in a greater consumption of calories (fat or sugar) and deteriorates their glycemic or lipid profiles but improves their perceived quality of life. RESEARCH DESIGN AND METHODS: In an 8-month randomized controlled trial, 48 free-living subjects with type 2 diabetes were taught either a conventional (C) meal plan (no concentrated sweets) or one permitting as much as 10% of total energy as added sugars or sweets (S). Mean individual nutrient intake was determined using the average of six 24-h telephone recalls per 4 months. Metabolic control and quality of life were evaluated every 2 months. Quality of life was assessed using the Medical Outcome Survey and the Diabetes Quality of Life questionnaire. RESULTS: The S group did not consume more calories (fat or sugar) and in fact ate significantly less carbohydrate (-15 vs. 10 g) and less starch (-7 vs. 8 g) and had a tendency to eat fewer calories (-77 vs. 81 kcal) than the C group. Weight remained stable, and there was no evidence that consuming more sugar worsened metabolic profile or improved their perceived quality of life. CONCLUSIONS: Giving individuals with type 2 diabetes the freedom to include sugar in their daily meal plan had no negative impact on dietary habits or metabolic control. Health professionals can be reassured and encouraged to teach the new "sugar guidelines," because doing so may result in a more conscientious carbohydrate consumption.     

Glycemic Index,Glycemic Load,Carbohydrates, and Type 2 Diabetes: Systematic review and dose–response meta-analysis of prospective studies

OBJECTIVE

Diets with high glycemic index (GI), with high glycemic load (GL), or high in all carbohydrates may predispose to higher blood glucose and insulin concentrations, glucose intolerance, and risk of type 2 diabetes. We aimed to conduct a systematic literature review and dose–response meta-analysis of evidence from prospective cohorts.

RESEARCH DESIGN AND METHODS

We searched the Cochrane Library, MEDLINE, MEDLINE in-process, Embase, CAB Abstracts, ISI Web of Science, and BIOSIS for prospective studies of GI, GL, and total carbohydrates in relation to risk of type 2 diabetes up to 17 July 2012. Data were extracted from 24 publications on 21 cohort studies. Studies using different exposure categories were combined on the same scale using linear and nonlinear dose–response trends. Summary relative risks (RRs) were estimated using random-effects meta-analysis.

RESULTS

The summary RR was 1.08 per 5 GI units (95% CI 1.02–1.15; P = 0.01), 1.03 per 20 GL units (95% CI 1.00–1.05; P = 0.02), and 0.97 per 50 g/day of carbohydrate (95% CI 0.90–1.06; P = 0.5). Dose–response trends were linear for GI and GL but more complex for total carbohydrate intake. Heterogeneity was high for all exposures (I² >50%), partly accounted for by different covariate adjustment and length of follow-up.

CONCLUSIONS

Included studies were observational and should be interpreted cautiously. However, our findings are consistent with protective effects of low dietary GI and GL, quantifying the range of intakes associated with lower risk. Future research could focus on the type of sugars and other carbohydrates associated with greatest risk.Type 2 diabetes is a leading cause of cardiovascular disease, with a global prevalence of 10% (1). An individual’s diet is considered to contribute to the development of type 2 diabetes, in particular, the capacity that foods containing carbohydrates have to increase blood glucose (2). It has been suggested that diets with high glycemic index (GI) or glycemic load (GL) may predispose to higher postprandial blood glucose and insulin concentrations, which, in turn, increase glucose intolerance and risk of eventual type 2 diabetes (3).A number of studies have indicated an association between GI, GL, and type 2 diabetes (4–8), but there are many other large studies that find no evidence to support the hypothesis (9–11). Accordingly, the American Diabetes Association’s dietary guidelines for diabetes prevention currently state that there is insufficient consistent evidence to say that diets low in GL reduce diabetes risk (12). There is also considerable inconsistency in results regarding the role of total carbohydrate intake.Two systematic reviews have concluded that there is evidence of a positive association between both dietary GI and GL and risk of type 2 diabetes (13,14), but with considerable unexplored heterogeneity. The comparison of only the most extreme categories, based on different definitions in each reviewed study, introduced additional heterogeneity and discarded information in the middle exposure categories, leading to uncertainty regarding the strength of the association. Combination of different definitions of the highest and lowest exposure categories meant that their summary estimates could not be related to a particular level of exposure, limiting the applicability of results in public health terms. Furthermore, the review did not assess the nature of any dose–response relationship, an important criterion for judging the chances of any associations being causal.Results from nine publications from eight large prospective studies have been published since the most recent review, including almost 20,000 cases of type 2 diabetes from over 250,000 participants. We therefore assess the evidence accumulated to date, investigating possible dose–response curves and formally exploring the potential causes of heterogeneity that may lead to deeper understanding of the nature of the associations.     

Dietary glycemic index, glycemic load, fiber, simple sugars, and insulin resistance: the Inter99 study

OBJECTIVE: To examine the relationship between daily glycemic index, daily glycemic load, simple sugars, dietary fiber, and the prevalence of a measure of insulin resistance in 30- to 60-year-old nondiabetic Danish men and women. RESEARCH DESIGN AND METHODS: The Inter99 study is a nonpharmacological intervention study. We used baseline data and examined cross-sectional associations between carbohydrate-related dietary factors and an estimate of insulin resistance in 5,675 subjects at 30-60 years. The dietary intake was estimated from a self-administered food frequency questionnaire, and insulin resistance was estimated using the homeostasis model assessment of insulin resistance (HOMA-IR). Multiple regressions were performed with HOMA-IR as the dependent variable and carbohydrate-related factors as explanatory variables. All models were adjusted for age, sex, smoking, physical activity, total energy intake, BMI, and waist circumference. RESULTS: Intake of lactose was positively associated with HOMA-IR (P < 0.0001), whereas daily glycemic load and intake of glucose, fructose, dietary fiber, total carbohydrate, fruit, and vegetables were inversely associated with HOMA-IR (P < 0.05). Intake of dietary fiber explained the associations with daily glycemic load and total carbohydrate and attenuated the association with fruit and vegetables. No significant associations were observed for daily glycemic index or sucrose. CONCLUSIONS: Habitual intake of diets with a high glycemic index and high glycemic load or diets with a high content of total carbohydrate including simple sugars was not associated with the probability of having insulin resistance. Furthermore, intake of dietary fiber was inversely associated with the probability of having insulin resistance.     

Glycemic index of foods in individual subjects

We studied 12 subjects with diabetes to determine how well the glycemic index (GI) predicted the ranking of glycemic responses of different foods in individuals. All subjects ate three mixed meals (bread, rice, or spaghetti with GIs of 100, 79, and 61, respectively) four times in a randomized complete block design. The mean glycemic response areas of the different meals ranked according to the predicted GI in every individual. The observed mean +/- SD GI values of the meals were significantly different from each other (bread 100 +/- 7, rice 75 +/- 9, spaghetti 54 +/- 9), with no significant difference in response between subjects. It is concluded that individuals share common mean GI values for different foods. Within confidence limits determined by the variability of glycemic responses, the number of repeated tests conducted, and the expected GI difference, the GI can be used to predict the ranking of the mean glycemic responses of mixed meals taken by individuals.     

Effects of meal carbohydrate content on insulin requirements in type 1 diabetic patients treated intensively with the basal-bolus (ultralente-regular) insulin regimen.

OBJECTIVE: In this study, we evaluated the effects of high-(55%) and low-(40%) carbohydrate diets on insulin requirements in nine type 1 diabetic subjects treated intensively with ultralente as basal insulin and regular insulin as premeal insulin adjusted to the carbohydrate content of meals. RESEARCH DESIGN AND METHODS: Nine subjects were randomized in a crossover design to follow two diets consecutively for a period of 14 days each. A 3-day food diary was completed for each diet with the amount of carbohydrate in the mixed meals ranging from 21 to 188 g. Preprandial (5.9 vs. 6.1 mmol/l) and postprandial (8 vs. 8.9 mmol/l) capillary glucose and fructosamine (310 vs. 316 mumol/l) were comparable on both the low- and high-carbohydrate diets. RESULTS: The assessment of meal carbohydrate content by the patients was excellent, with > 85% of cases falling within 15% of computer-assisted evaluation. When premeal regular insulin was prescribed in U/10 g of carbohydrate, the postprandial glycemic rise remained constant (2.4 +/- 2.8 mmol/l) over a wide range of carbohydrate ingested (21-188 g) and was not affected by the glycemic index, fiber, and caloric and lipidic content of the meals. This tight control was maintained during the low- and high-carbohydrate diet without any change in insulin requirements (breakfast, 1.5 vs. 1.5 U/10 g of carbohydrate; lunch, 1.0 vs. 1.0; supper, 1.1 vs. 1.2) and in basal ultralente insulin requirements (22.5 vs. 21.4 U/day). CONCLUSIONS: These results indicate that in type 1 diabetic subjects 1) increasing the amount of carbohydrate intake does not influence glycemic control if premeal regular insulin is adjusted to the carbohydrate content of the meals; 2) algorithms based on U/10 g of carbohydrate are effective and safe, whatever the amount of carbohydrate in the meal; 3) the glycemic index, fiber, and lipidic and caloric content of the meals do not affect premeal regular insulin requirements; 4) wide variations in carbohydrate intake do not modify basal (ultralente) insulin requirements; and, finally 5) the ultralente-regular insulin regimen allows dissection between basal and prandial insulin requirements, so that each can be adjusted accurately and independently.     

Risk factors for frequent and severe hypoglycemia in type 1 diabetes.

OBJECTIVE: To determine the risk of frequent and severe hypoglycemia and the associated demographic and clinical risk factors. RESEARCH DESIGN AND METHODS: Demographic and diabetes self-management factors were measured in 415 subjects followed prospectively for 4-6.5 years of type 1 diabetes duration as participants in a population-based incident cohort. Blood samples were collected up to three times yearly to test glycosylated hemoglobin (GHb) levels. Reports of frequent (2-4 times/week) and severe (lost consciousness) hypoglycemia as well as other diabetes self-management data were collected by questionnaires. RESULTS: Frequent hypoglycemia was common (33 and 35% of participants reported this on the 4- and 6.5-year questionnaires, respectively), whereas severe hypoglycemia occurred much less often. Better glycemic control (odds ratio [OR] 1.3 per 2% decrease in GHb, 95% CI 1.1-1.5) and more frequent self-monitored blood glucose (1.5 per blood glucose check, 1.3-1.7) were independently related to frequent hypoglycemia. The association of frequent hypoglycemia with intensive insulin therapy increased with age. Better glycemic control (1.5 per 2% decrease in GHb, 1.2-2.0) and older age were related to severe hypoglycemic reactions. No sociodemographic factors other than age increased the risk of hypoglycemia. CONCLUSIONS: Frequent hypoglycemia was common in a population representing the full range of glycemic control in the community. Intensive insulin management and blood glucose monitoring independently predicted frequent but not severe hypoglycemia. This information may be useful for updating patients such that minor changes in diabetes management might decrease the daily burden of this condition while maintaining intensive insulin therapy.     

Iron intake and the risk of type 2 diabetes in women: a prospective cohort study

OBJECTIVE: Epidemiological studies suggest that high body iron stores are associated with insulin resistance and type 2 diabetes. The aim of this study was to evaluate the association between dietary intake of iron and the risk of type 2 diabetes. RESEARCH DESIGN AND METHODS: We conducted a prospective cohort study within the Nurses' Health Study. We followed 85,031 healthy women aged 34-59 years from 1980 to 2000. Dietary data were collected every 4 years, and data on medical history and lifestyle factors were updated biennially. RESULTS: During the 20 years of follow-up, we documented 4,599 incident cases of type 2 diabetes. We found no association between total, dietary, supplemental, or nonheme iron and the risk of type 2 diabetes. However, heme iron intake (derived from animal products) was positively associated with risk; relative risks (RRs) across increasing quintiles of cumulative intake were 1.00, 1.08 (95% CI 0.97-1.19), 1.20 (1.09-1.33), 1.27 (1.14-1.41), and 1.28 (1.14-1.45) (P(trend) < 0.0001) after controlling for age, BMI, and other nondietary and dietary risk factors. In addition, when we modeled heme iron in seven categories, the multivariate RR comparing women who consumed > or =2.25 mg/day and those with intake <0.75 mg/day was 1.52 (1.22-1.88). The association between heme iron and the risk of diabetes was significant in both overweight and lean women. CONCLUSIONS: This large cohort study suggests that higher heme iron intake is associated with a significantly increased risk of type 2 diabetes.     

Habitually Higher Dietary Glycemic Index During Puberty Is Prospectively Related to Increased Risk Markers of Type 2 Diabetes in Younger Adulthood

OBJECTIVE

Carbohydrate nutrition during periods of physiological insulin resistance such as puberty may affect future risk of type 2 diabetes. This study examined whether the amount or the quality (dietary glycemic index [GI], glycemic load [GL], and added sugar, fiber, and whole-grain intake) of carbohydrates during puberty is associated with risk markers of type 2 diabetes in younger adulthood.

RESEARCH DESIGN AND METHODS

The analysis was based on 226 participants (121 girls and 105 boys) from the Dortmund Nutritional and Anthropometric Longitudinally Designed Study (DONALD) with an average of five 3-day weighed dietary records (range 2–6) during puberty (girls, age 9–14 years; boys, age 10–15 years) and fasting blood samples in younger adulthood (age 18–36 years) (average duration of follow-up 12.6 years). Multivariable linear regression was used to analyze the associations between carbohydrate nutrition and homeostasis model assessment–insulin resistance (HOMA-IR) as well as the liver enzymes alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT) (n = 214).

RESULTS

A higher dietary GI was prospectively related to greater values of HOMA-IR (P_trend = 0.03), ALT (P_trend = 0.02), and GGT (P_trend = 0.04). After adjustment for sex, adult age, baseline BMI, and early life and socioeconomic factors as well as protein and fiber intake, predicted mean HOMA-IR values in energy-adjusted tertiles of GI were 2.37 (95% CI 2.16–2.60), 2.47 (2.26–2.71), and 2.59 (2.35–2.85). The amount of carbohydrates, GL, and added sugar, fiber, and whole-grain intake were not related to the analyzed markers.

CONCLUSIONS

Our data indicate that a habitually higher dietary GI during puberty may adversely affect risk markers of type 2 diabetes in younger adulthood.Concern has been raised that the commonly advocated low-fat, high-carbohydrate diet may be detrimental for the growing number of persons with impaired glucose tolerance even among youths, since it induces postprandial rises in glucose and insulin and may thereby increase the risk the risk of developing type 2 diabetes (1,2). Observational evidence suggests that dietary glycemic index (GI) and glycemic load (GL) are related to risk of type 2 diabetes (3,4), yet it remains to be determined whether the relevance of postprandial rises in glucose and insulin extends to puberty—a period characterized by a physiological insulin resistance (5).Chronic postprandial hyperglycemia and hyperinsulinemia can also exacerbate hepatic insulin resistance: enhanced glucose uptake by the liver subsequently leads to increased hepatic fat accumulation through upregulated de novo lipogenesis. In fact, hepatic fat accumulation is frequently observed in patients with insulin resistance or type 2 diabetes (6). The liver enzymes alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT) are commonly used as surrogate parameters for hepatic fat content and are now recognized as risk markers for type 2 diabetes (7,8). Furthermore, preliminary evidence supports a role of carbohydrate nutrition for hepatic steatosis and these indirect markers of liver fat (9).This study addressed the hypothesis that recurring postprandial glycemic excursions during puberty are of specific relevance for later risk of type 2 diabetes. Since calculated dietary GI is a valid predictor of glycemic responses (10,11), we postulate that dietary GI estimated from 3-day dietary records repeatedly collected during puberty is a better predictor of type 2 diabetes risk in younger adulthood than intakes of dietary fiber, whole grain, or added sugar. This hypothesis was addressed using data from a cohort of healthy young Germans. The homeostasis model assessment–insulin resistance (HOMA-IR) index and the liver enzymes ALT and GGT was used as risk markers of type 2 diabetes.     

Effect of wheat bran on glycemic control and risk factors for cardiovascular disease in type 2 diabetes

OBJECTIVE: Cohort studies indicate that cereal fiber reduces the risk of diabetes and coronary heart disease (CHD). Therefore, we assessed the effect of wheat bran on glycemic control and CHD risk factors in type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 23 subjects with type 2 diabetes (16 men and 7 postmenopausal women) completed two 3-month phases of a randomized crossover study. In the test phase, bread and breakfast cereals were provided as products high in cereal fiber (19 g/day additional cereal fiber). In the control phase, supplements were low in fiber (4 g/day additional cereal fiber). RESULTS: Between the test and control treatments, no differences were seen in body weight, fasting blood glucose, HbA(1c), serum lipids, apolipoproteins, blood pressure, serum uric acid, clotting factors, homocysteine, C-reactive protein, magnesium, calcium, iron, or ferritin. LDL oxidation in the test phase was higher than that seen in the control phase (12.1 +/- 5.4%, P < 0.034). Of the subjects originally recruited, more dropped out of the study for health and food preference reasons from the control phase (16 subjects) than the test phase (11 subjects). CONCLUSIONS: High-fiber cereal foods did not improve conventional markers of glycemic control or risk factors for CHD in type 2 diabetes over 3 months. Possibly longer studies are required to demonstrate the benefits of cereal fiber. Alternatively, cereal fiber in the diet may be a marker for another component of whole grains that imparts health advantages or a healthy lifestyle.     

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. RESEARCH DESIGN AND 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. CONCLUSION: 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.     

Improved glycemic control and lipid profile and normalized fibrinolytic activity on a low-glycemic index diet in type 2 diabetic patients.

OBJECTIVE: To evaluate the effects of varying the glycemic index (GI) of carbohydrate-rich foods on metabolic control in type 2 diabetic patients. RESEARCH DESIGN AND METHODS: In a randomized crossover study, 20 patients, 5 women and 15 men, were given preweighed diets with different GIs during two consecutive 24-day periods. Both diets were composed in accordance with dietary recommendations for people with diabetes. The macronutrient composition and type and amount of dietary fiber were identical. Differences in GI were achieved mainly by altering the structure of the starchy foods. RESULTS: Peripheral insulin sensitivity increased significantly and fasting plasma glucose decreased during both treatment periods. There was a significant difference in the changes of serum fructosamine concentrations between the diets (P < 0.05). The incremental area under the curve for both blood glucose and plasma insulin was approximately 30% lower after the low- than after the high-GI diet. LDL cholesterol was significantly lowered on both diets, with a significantly more pronounced reduction on the low-GI diet. Plasminogen activator inhibitor-1 activity was normalized on the low-GI diet, (-54%, P < 0.001), but remained unchanged on the high-GI diet. CONCLUSIONS: A diet characterized by low-GI starchy foods lowers the glucose and insulin responses throughout the day and improves the lipid profile and capacity for fibrinolysis, suggesting a therapeutic potential in diabetes.