A prospective study of dietary patterns, meat intake and the risk of gestational diabetes mellitus

Gestational Diabetes

Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy and is strongly related to subsequent risk of type 2 diabetes. The epidemics of obesity and diabetes and the increasing incidence of GDM in recent years highlight the importance of preventing GDM among women at high risk to avoid the associated short- and long-term adverse health outcomes for both mothers and their offspring. Indeed, women may be more likely to adopt healthy lifestyle habits during pregnancy and maintain these habits into the postpartum period. Although there is substantial evidence that targeting at-risk groups for type 2 diabetes prevention is effective if lifestyle changes are made, relatively little attention has been paid to the prevention of GDM. Therefore, the objective of this article is to review the scientific evidence regarding the association between modifiable risk factors and GDM; discuss how lifestyle interventions, including weight management through diet and exercise could be successful in reducing the risk for GDM; and provide recommendations for future lifestyle intervention programs with a focus on translation and dissemination of research findings.

A prospective study of prepregnancy dietary fat intake and risk of gestational diabetes

BACKGROUND

Fatty acids play a vital role in glucose homeostasis; however, studies on habitual dietary fat intakes and gestational diabetes mellitus (GDM) risk are limited and provide conflicting findings.

OBJECTIVE

We determined whether the total amount and the type and source of prepregnancy dietary fats are related to risk of GDM.

DESIGN

A prospective study was conducted in 13,475 women who reported a singleton pregnancy between 1991 and 2001 in the Nurses' Health Study II. In these women, 860 incident GDM cases were reported. The adjusted RR of GDM was estimated for quintiles of total fat, specific fat, and the source of fat intakes by pooled logistic regression.

RESULTS

Higher animal fat and cholesterol intakes were significantly associated with increased GDM risk. Across increasing quintiles of animal fat, RRs (95% CIs) for GDM were 1.00 (reference), 1.55 (1.20, 1.98), 1.43 (1.09, 1.88), 1.40 (1.04, 1.89), and 1.88 (1.36, 2.60) (P-trend = 0.05). Corresponding RRs (95% CIs) for dietary cholesterol were 1.00 (reference), 1.08 (0.84, 1.32), 1.02 (0.78, 1.29), 1.20 (0.93, 1.55), and 1.45 (1.11, 1.89) (P-trend = 0.04). The substitution of 5% of energy from animal fat for an equal percentage of energy from carbohydrates was associated with significantly increased risk of GDM [RR (95% CI): 1.13 (1.08, 1.18); P < 0.0001]. No significant associations were observed between dietary polyunsaturated fat, monounsaturated fat, or trans fat intakes and GDM risk.

CONCLUSION

Higher prepregnancy intakes of animal fat and cholesterol were associated with elevated GDM risk.

Risk factors for gestational diabetes mellitus in a large population of women living in Spain: implications for preventative strategies

The aim of this study is to establish a risk appraisal model for GDM by identifying modifiable factors that can help predict the risk of GDM in a large population of 2194 women living in Spain. They were recruited between 2009-2010 when screening for GDM was performed. Participants completed a questionnaire on socio-demographic, anthropomorphic and behavioral characteristics, and reproductive and medical history. A total of 213 (9.7%) women were diagnosed as having GDM. Age, pregestational body weight (BW) and body mass index (BMI), and number of events of medical, obstetric and family history were significantly associated with GDM. After logistic regression model, biscuits and pastries intake <4 times/week, red and processed meats intake <6 servings/week, sugared drinks <4 servings/week, light walking >30 minutes/day, and 30 minutes/day of sports at least 2 days/week, compared with opposite consumption, was associated with less GDM risk. Our study identified several pregestational modifiable lifestyle risk factors associated with an increase in the risk of developing GDM. This may represent a promising approach for the prevention of GDM and subsequent complications. Further intervention studies are needed to evaluate if this appraisal model of risk calculation can be useful for prevention and treatment of GDM.

Physical activity and dietary behaviors associated with weight gain and impaired glucose tolerance among pregnant Latinas

Pregnancy has been proposed as a critical period for the development of subsequent maternal overweight and/or obesity. Excessive gestational weight gain is, in turn, associated with maternal complications such as cesarean delivery, hypertension, preeclampsia, impaired glucose tolerance, and gestational diabetes mellitus. Although there is substantial evidence that targeting at-risk groups for type 2 diabetes prevention is effective if lifestyle changes are made, relatively little attention has been paid to the prevention of excessive gestational weight gain and impaired glucose tolerance during pregnancy. Latinos are the largest minority group in the United States, with the highest birth and immigration rates of any minority group and are disproportionately affected by overweight and obesity. However, due to cultural factors, socioeconomic factors, and language barriers, Latinos have had limited access to public health interventions that promote healthy lifestyles. Therefore, the objective of this article is to review the scientific evidence regarding the association between physical activity, dietary behaviors, and gestational weight gain and impaired glucose tolerance among Latinas. A second objective is to discuss how lifestyle interventions including weight management through diet and exercise could be successful in reducing the risk of excessive gestational weight gain and gestational diabetes mellitus. Finally, recommendations are provided for future lifestyle intervention programs in this population with a focus on translation and dissemination of research findings.

Effect of dietary and lifestyle factors on the risk of gestational diabetes: review of epidemiologic evidence

Gestational diabetes mellitus (GDM), defined as glucose intolerance with onset or first recognition in pregnancy, is a common pregnancy complication and a growing health concern. GDM has been related to significant short-term and long-term adverse health outcomes for both mothers and offspring. Importantly, this number is increasing with the increasing burden of obesity among women of reproductive age. Collectively, these data highlight the significance of understanding risk factors, in particular modifiable factors, for GDM and of preventing GDM among high-risk populations. Research in the past decade has identified a few diet and lifestyle factors that are associated with GDM risk. This review provides an overview of emerging diet and lifestyle factors that may contribute to the prevention of GDM. It also discusses major methodologic concerns about the available epidemiologic studies of GDM risk factors.

Diet quality is related to eating competence in cross-sectional sample of low-income females surveyed in Pennsylvania

Women participants of two federally administered nutrition education programs (n=149, 56% white, 64% food secure, 86% 18-50 years of age,) completed telephone interviews that included three 24-hour dietary recalls and the Satter Eating Competence Inventory. Eating competence is delineated by an Inventory score≥32. Competent eaters had significantly greater intakes of fiber, vitamin A, vitamin E, vitamin C, most B-vitamins, magnesium, iron, zinc, potassium and a higher Healthy Eating Index. Two dietary patterns defined as Prudent and Western were observed. The Prudent pattern was correlated with eating competence and characterized by more healthful foods such as fruits, vegetables and low-fat dairy products. The Western pattern, characterized by foods higher in fat, salt, and sugar, was not related to eating competence. Findings suggest that dietary guidance using an eating competence approach for low-income women is compatible with goals to improve dietary quality and eating patterns.

Health Implications of a Vegetarian Diet

There is now a significant amount of research that demonstrates the health benefits of vegetarian and plant-based diets, which have been associated with a reduced risk of obesity, diabetes, heart disease, and some types of cancer as well as increased longevity. Vegetarian diets are typically lower in fat, particularly saturated fat, and higher in dietary fiber. They are also likely to include more whole grains, legumes, nuts, and soy protein, and together with the absence of red meat, this type of eating plan may provide many benefits for the prevention and treatment of obesity and chronic health problems, including diabetes and cardiovascular disease. Although a well-planned vegetarian or vegan diet can meet all the nutritional needs of an individual, it may be necessary to pay particular attention to some nutrients to ensure an adequate intake, particularly if the person is on a vegan diet. This article will review the evidence for the health benefits of a vegetarian diet and also discuss strategies for meeting the nutritional needs of those following a vegetarian or plant-based eating pattern.

International migration and gestational diabetes mellitus: a systematic review of the literature and meta-analysis

Influxes of migrant women of childbearing age to receiving countries have made their perinatal health status a key priority for many governments. The international research collaboration Reproductive Outcomes And Migration (ROAM) reviewed published studies to assess whether migrants in countries of resettlement have a greater risk of gestational diabetes mellitus (GDM) than women in receiving countries. A systematic review of the literature from Medline, Embase, PsychInfo and CINAHL from 1990 to 2009 included studies of migrant women and GDM. Studies were excluded if there was no cross-border movement or comparison group or if the receiving country was not the country of resettlement. Studies were assessed for quality, analysed descriptively and meta-analysed. Twenty-four reports (representing >120,000 migrants) met our inclusion criteria. Migrants were described primarily by geographic origin; other relevant aspects (e.g. time in country, language fluency) were rarely studied. Migrants' results for GDM were worse than those for receiving-country women in 79% of all studies. Meta-analyses showed that, compared with receiving-country women, Caribbean, African, European and Northern European women were at greater risk of GDM, while North Africans and North Americans had risks similar to receiving-country women. Although results of the 31 comparisons of Asians, East Africans or non-Australian Oceanians were too heterogeneous to provide a single GDM risk estimate for migrant women, only one comparison was below the receiving-country comparison group, all others presented a higher risk estimate. The majority of women migrants to resettlement countries are at greater risk for GDM than women resident in receiving countries. Research using clear, specific migrant definitions, adjusting for relevant risk factors and including other aspects of migration experiences is needed to confirm and understand these findings.

Pregravid physical activity, dietary intake, and glucose intolerance during pregnancy

OBJECTIVES

To ascertain prepregnancy physical activity and dietary intake from a sample of women in early pregnancy and estimate the effect of prepregnancy lifestyle behaviors on the 1-hour glucose challenge test (GCT).

METHODS

We conducted a prospective analysis of a racially diverse urban-based sample of 152 pregnant women in the first trimester who were participants in the Parity, Inflammation and Diabetes (PID) study. Dietary intake before pregnancy was assessed using a modified version of the Block Rapid Food Screener, and leisure time physical activity before pregnancy was assessed using the Baecke questionnaire. Test results from a nonfasting oral GCT conducted between 26 and 28 weeks were abstracted from the medical record. Participants were classified as having a positive GCT if the blood glucose measurement was ≥140 mg/dL and as negative with a blood glucose measurement <140 mg/dL. We constructed a series of multiple logistic regression models, adjusting for potential confounders to determine if prepregnancy dietary intake and leisure activity were associated with response to the GCT.

RESULTS

Women with higher prepregnancy leisure activity scores were 68% less likely to have a 1-hour GCT response ≥140mg/dL. However, there was no association between dietary intake and response to the GCT.

CONCLUSIONS

Our data suggest that prevention of an abnormal GCT result should include practices to encourage women of reproductive age to engage in leisure physical activity in advance of planning a pregnancy.

A Comparative Study of Eating Habits and Food Intake in Women with Gestational Diabetes according to Early Postpartum Glucose Tolerance Status

BACKGROUND

Women with gestational diabetes mellitus (GDM) are at high risk for type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD); continuous life-style intervention, especially diet, is central to managing T2DM and CVD. However, little is known about the dietary patterns of women with GDM after delivery. The goal of this study was to compare the eating habits and food intakes of women diagnosed with GDM during the early postpartum period.

METHODS

We performed a 75 g oral glucose tolerance test (OGTT) in 184 women with GDM between 6 and 12 weeks after delivery. Based on the results of the OGTT, the subjects were divided into three groups according to the American Diabetes Association criteria; normal glucose tolerance (NGT) (n=100), pre-diabetes (n=73), and diabetes mellitus (DM) (n=11). Eating habits and usual food intake after delivery were investigated using a questionnaire, based on 24 hour-recall, which was administered by a trained dietitian. The daily intake data were analyzed using CAN Pro 3.0. Blood tests were performed pre- and post-delivery.

RESULTS

Eating habits were not significantly different among the three groups. However, animal fat consumption was significantly different among the three groups. The intake ratio of fat calories to total calories was also significantly higher in the pre-diabetes and DM groups.

CONCLUSION

Although diet in the period 6 to 12 weeks postpartum did not influence glucose level, it may be important to educate women with GDM about the risks of excessive animal fat intake during pregnancy and the postpartum period in order to prevent later onset of T2DM.

PPAR Action in Human Placental Development and Pregnancy and Its Complications

During pregnancy crucial anatomic, physiologic, and metabolic changes challenge the mother and the fetus. The placenta is a remarkable organ that allows the mother and the fetus to adapt to the new metabolic, immunologic, and angiogenic environment imposed by gestation. One of the physiologic systems that appears to have evolved to sustain this metabolic regulation is mediated by peroxisome proliferator-activated receptors (PPARs). In clinical pregnancy-specific disorders, including preeclampsia, gestational diabetes, and intrauterine growth restriction, aberrant regulation of components of the PPAR system parallels dysregulation of metabolism, inflammation and angiogenesis. This review summarizes current knowledge on the role of PPARs in regulating human trophoblast invasion, early placental development, and also in the physiology of clinical pregnancy and its complications. As increasingly indicated in the literature, pregnancy disorders, such as preeclampsia and gestational diabetes, represent potential targets for treatment with PPAR ligands. With the advent of more specific PPAR agonists that exhibit efficacy in ameliorating metabolic, inflammatory, and angiogenic disturbances, further studies of their application in pregnancy-related diseases are warranted.

Pregravid cardiometabolic risk profile and risk for gestational diabetes mellitus

OBJECTIVE

The purpose of this study was to examine pregravid cardiometabolic profile and subsequent risk of gestational diabetes mellitus (GDM).

STUDY DESIGN

GDM cases (n = 199) and control subjects (n = 381) were selected from a cohort of women who took part in a multiphasic health checkup examination at Kaiser Permanente from 1984-1996 and who had a subsequent pregnancy and were matched by year and age at multiphasic health checkup examination and age at delivery.

RESULTS

Pregravid measurements of serum glucose levels of 100-140 mg/dL, body mass index of ≥ 25.0 kg/m(2), and prehypertension/hypertension level were associated independently with GDM risk (odds ratios [OR], 4.8; 95% confidence interval [CI], 1.7-13.9; OR, 2.7; 95% CI, 1.6-4.3; and OR, 1.5; 95% CI, 1.0-2.3, respectively). The risk of GDM increased with the number of cardiometabolic risk factors (P < .001); adverse levels of both body mass index and glucose were associated with a 4.6-fold increased risk of GDM, compared with women with normal levels (P = .0001).

CONCLUSION

Pregravid cardiometabolic risk profile may help clinicians to identify high-risk women to target for primary prevention or early management of GDM.

Risk of gestational diabetes mellitus in relation to maternal egg and cholesterol intake

Higher egg and cholesterol intakes are associated with increased risk of type 2 diabetes mellitus. However, their association with gestational diabetes mellitus (GDM) has not been evaluated. The authors assessed such associations in both a prospective cohort study (1996-2008; 3,158 participants) and a case-control study (1998-2002; 185 cases, 411 controls). A food frequency questionnaire was used to assess maternal diet. Multivariable models were used to derive relative risks and 95% confidence intervals. Compared with no egg consumption, adjusted relative risks for GDM were 0.94, 1.01, 1.12, 1.54, and 2.52 for consumption of ≤1, 2-3, 4-6, 7-9, and ≥10 eggs/week, respectively (P for trend=0.008). Women with high egg consumption (≥7/week) had a 1.77-fold increased risk compared with women with lower consumption (95% confidence interval (CI): 1.19, 2.63). The relative risk for the highest quartile of cholesterol intake (≥294 mg/day) versus the lowest (<151 mg/day) was 2.35 (95% CI: 1.35, 4.09). In the case-control study, the adjusted odds ratio for consuming ≥7 eggs/week versus <7 eggs/week was 2.65 (95% CI: 1.48, 4.72), and the odds of GDM increased with increasing cholesterol intake (P for trend=0.021). In conclusion, high egg and cholesterol intakes before and during pregnancy are associated with increased risk of GDM.

Obesity and diabetes in mothers and their children: can we stop the intergenerational cycle?

Obesity prevalence in the United States has reached an alarming level. Consequently, more young women are entering pregnancy with body mass indices of at least 30 kg/m(2). While higher maternal weight entering pregnancy is related to several adverse pregnancy outcomes, some of the strongest and most compelling data to date have linked prepregnancy obesity to gestational diabetes mellitus (GDM). The mechanisms by which excess maternal weight influences metabolic dysfunction in pregnancy are similar to those in obese nonpregnant women; adipocytes are metabolically active and release a number of hormones implicated in insulin resistance. Heavier mothers are also more likely to have higher glucose levels that do not exceed the cutoff for GDM, but nevertheless predict poor perinatal outcomes. Longer-term complications of GDM include increased risk of maternal type 2 diabetes and offspring obesity. Promising intervention studies to decrease the intergenerational cycle of obesity and diabetes are currently underway.

Vegetarian Diets and Diabetes

A large body of evidence suggests that vegetarian and plant-based diets provide exceptional health benefits, including a reduced risk of obesity, diabetes, heart disease and some types of cancer, and increased longevity. Vegetarian diets are typically lower in fat, particularly saturated fat, and higher in dietary fiber. They are also likely to include more whole grains, legumes, nuts, and soy protein, which together provide micro-nutrients and protective factors at higher levels than most Western diets. In observational studies, a vegetarian or vegan diet is associated with reduced risk of development of type 2 diabetes and lower risk of complications in those with existing diabetes. Although it is often difficult to separate vegetarianism from other healthy lifestyle behaviors, this eating pattern and the absence of red meat and processed meat products may provide particular benefits in the management of diabetes and prediabetes. This article critically reviews the scientific evidence for the role of vegetarian diets in the prevention and management of diabetes.

Gestational diabetes: risk factors and recent advances in its genetics and treatment

The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study of over 23000 diabetes-free pregnancies has shown that at a population level an unequivocal linear relationship exists between maternal glucose concentrations around the beginning of the third trimester of pregnancy and the risk of their baby being born above the ninetieth centile for weight. With the rising incidence of gestational diabetes (GDM) across the developed world, largely paralleling the increased prevalence of obesity, there has been a sharp increase in the risk of pregnancy complications developing related to the birth of macrosomic babies. The associated additional long-term complications of GDM pregnancies means that in the future there is likely to be a large increase in the incidence of type 2 diabetes and associated conditions in both the mothers and their affected offspring. The present review seeks to highlight recent advances and remaining gaps in knowledge about GDM in terms of its genetics (where some of the recently discovered polymorphic risk factors for type 2 diabetes have also proved to be risk factors for GDM) and its treatment by diet, exercise and drugs.

The association between depression and diabetes in the perinatal period

Both depression and diabetes are common in the perinatal period and result in serious consequences for mother and fetus. Although the association between depression and diabetes is well established, few studies have examined the association between these disorders during the perinatal period, when the etiology of depression and diabetes may differ from other periods over the life course. This article reviews the four most relevant epidemiologic papers that examined the association between depression and diabetes in the perinatal period and makes recommendations for future studies about how best to examine the association between these disorders during the perinatal period.

Neighbourhood food environment and gestational diabetes in New York City

The association between neighbourhood characteristics and gestational diabetes has not been examined previously. We investigated the relationship between the number of healthy food outlets (supermarkets; fruit/vegetable and natural food stores), and unhealthy food outlets (fast food; pizza; bodegas; bakeries; convenience, candy/nut and meat stores) in census tract of residence, and gestational diabetes in New York City. Gestational diabetes, census tract and individual-level covariates were ascertained from linked birth-hospital data for 210 926 singleton births from 2001 to 2002 and linked to commercial data on retail food outlets. Adjusted odds ratios (aOR) were estimated using a multilevel logistic model. No association between food environment measures and gestational diabetes was found, with aORs ranging from 0.95 to 1.04. However, an increased odds of pre-pregnancy weight >200 lbs for women living in a given neighbourhood with no healthy food outlets [aOR = 1.14, 95% CI 1.07, 1.21] or only one healthy food place [aOR = 1.10, 95% CI 1.04, 1.18] relative to two or more healthy food outlets was found. Due to probable misclassification of neighbourhood food environment and pre-pregnancy obesity results are likely to be biased towards the null. Future research, including validity studies, on the neighbourhood food environment, obesity during pregnancy and gestational diabetes is warranted.

Prospective study of pre-gravid sugar-sweetened beverage consumption and the risk of gestational diabetes mellitus

OBJECTIVE

Consumption of sugar-sweetened beverages (SSBs) was related to an elevated risk of type 2 diabetes and insulin resistance in several recent studies among middle- or older-aged populations. Studies on SSB consumption and glucose intolerance among pregnant women, however, are lacking. We therefore examined the association between regular SSB consumption before pregnancy and the risk of gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND METHODS

This was a prospective study among 13,475 U.S. women who reported at least one singleton pregnancy between 1992 and 2001 in the Nurses' Health Study II. GDM was self-reported and validated by medical record review in a subsample. Cox proportional hazards models with multivariate adjustments were applied to examine the association of SSB consumption with GDM risk.

RESULTS

During 10 years of follow-up, 860 incident GDM case subjects were identified. After adjustment for age, parity, race, physical activity, smoking, alcohol intake, prepregnancy BMI, and Western dietary pattern, intake of sugar-sweetened cola was positively associated with the risk of GDM, whereas no significant association was found for other SSBs and diet beverages. Compared with women who consumed <1 serving/month, those who consumed >or=5 servings/week of sugar-sweetened cola had a 22% greater GDM risk (relative risk 1.22 [95% CI 1.01-1.47]).

CONCLUSIONS

Findings from this study suggest that prepregnancy higher consumption of sugar-sweetened cola (>or=5 servings/week) is associated with an elevated GDM risk, whereas no significant association with GDM risk was observed for other SSBs and diet beverages.

Discipline-specific insulin sensitivity in athletes

OBJECTIVE

Weight status and abnormal liver function are the two factors that influence whole-body insulin sensitivity. The main goal of the study was to compare insulin sensitivity in athletes (n=757) and physically active controls (n=670) in relation to the two factors.

METHODS

Homeostatic metabolic assessment for insulin resistance (HOMA-IR), weight status, and abnormal liver function (alanine aminotransferase and aspartate aminotransferase) were determined from 33 sports disciplines under morning fasted condition. This study was initiated in autumn 2006 and repeated in autumn 2007 (n=1508) to ensure consistency of all observations.

RESULTS

In general, HOMA-IR and blood pressure levels in athletes were significantly greater than those in physically active controls but varied widely with sport disciplines. Rowing and short-distance track athletes had significantly lower HOMA-IR values and archery and field-throwing athletes had significantly higher values than the control group. Intriguingly, athletes from 22 sports disciplines displayed significantly greater body mass index values above control values. Multiple regression analysis showed that, for non-athlete controls, body mass index was the only factor that contributed to the variations in HOMA-IR. For athletes, body mass index and alanine aminotransferase independently contributed to the variation of HOMA-IR.

CONCLUSION

This is the first report documenting HOMA-IR values in athletes from a broad range of sport disciplines. Weight status and abnormal liver function levels appear to be the major contributors predicting insulin sensitivity for the physically active population.

Dietary patterns and nutritional adequacy in a Mediterranean country

Dietary patterns have been related to health outcomes and morbi-mortality. Mediterranean diet indexes are correlated with adequate nutrient intake. The objective of the present study was to analyse the adequacy of nutrient intake ofa posterioridefined Mediterranean (MDP) and Western (WDP) diet patterns in the Seguimiento Universidad de Navarra (SUN) cohort. A sample of 17 197 subjects participated in the study. Participants completed a 136-item validated semi-quantitative FFQ. Principal component analysis was used to define dietary patterns. Individuals were classified according to quintiles of adherence based on dietary pattern scores. Non-dietary variables, such as smoking and physical activity habits, were also taken into account. The probability approach was used to assess nutrient intake adequacy of certain vitamins (vitamins B12, B6, B3, B2, B1, A, C, D and E) and minerals (Na, Zn, iodine, Se, folic acid, P, Mg, K, Fe and Ca). Logistic regression analysis was used to assess the adequacy of nutrient intake according to adherence to dietary patterns. WDP and MDP were defined. A higher quintile of adherence to an MDP was associated to a lower prevalence of inadequacy for the intake of Zn, iodine, vitamin E, Mg, Fe, vitamin B1, vitamin A, Se, vitamin C and folic acid. The adjusted OR for not reaching at least six (or at least ten) nutrient recommendations were 0·09 (95 % CI: 0·07, 0·11) (and 0·02 (95 % CI: 0·00, 0·16)) for the upper quintile of MDP and 4·4 (95 % CI: 3·6, 5·5) and 2·5 (95 % CI: 1·1, 5·4) for the WDP. The MDP was associated to a better profile of nutrient intake.

Pre-gravid physical activity and reduced risk of glucose intolerance in pregnancy: the role of insulin sensitivity

OBJECTIVE

Pre-gravid physical activity has been associated with a reduced risk of gestational diabetes mellitus (GDM), although neither the types of exercise nor the physiologic mechanisms underlying this protective effect have been well-studied. Thus, we sought to study the relationships between types of pre-gravid physical activity and metabolic parameters in pregnancy, including glucose tolerance, insulin sensitivity and beta-cell function.

DESIGN/PATIENTS/MEASUREMENTS

A total of 851 women underwent a glucose challenge test (GCT) and a 3-h oral glucose tolerance test (OGTT) in late pregnancy, yielding four glucose tolerance groups: (i) GDM; (ii) gestational impaired glucose tolerance (GIGT); (iii) abnormal GCT with normal glucose tolerance on OGTT (abnormal GCT NGT); and (iv) normal GCT with NGT on OGTT (normal GCT NGT). Pre-gravid physical activity was assessed using the Baecke questionnaire, which measures (i) total physical activity and (ii) its three component domains: work, nonsport leisure-time, and vigorous/sports activity.

RESULTS

Glucose tolerance status improved across increasing quartiles of pre-gravid total physical activity (P = 0.0244). Whereas neither work nor nonsport leisure-time activity differed between glucose tolerance groups, pre-gravid vigorous/sports activity was significantly higher in women with normal GCT NGT compared to women with (i) abnormal GCT NGT (P = 0.0018) (ii) GIGT (P = 0.0025), and (iii) GDM (P = 0.0044). In particular, vigorous/sports activity correlated with insulin sensitivity (measured by IS(OGTT)) (r = 0.21, P < 0.0001). Furthermore, on multiple linear regression analysis, pre-gravid vigorous/sports activity emerged as a significant independent predictor of IS(OGTT) in pregnancy (t = 4.97, P < 0.0001).

CONCLUSIONS

Pre-gravid vigorous/sports activity is associated with a reduced risk of glucose intolerance in pregnancy, an effect likely mediated by enhanced insulin sensitivity.

Hypothesis: could excessive fructose intake and uric acid cause type 2 diabetes?

We propose that excessive fructose intake (>50 g/d) may be one of the underlying etiologies of metabolic syndrome and type 2 diabetes. The primary sources of fructose are sugar (sucrose) and high fructose corn syrup. First, fructose intake correlates closely with the rate of diabetes worldwide. Second, unlike other sugars, the ingestion of excessive fructose induces features of metabolic syndrome in both laboratory animals and humans. Third, fructose appears to mediate the metabolic syndrome in part by raising uric acid, and there are now extensive experimental and clinical data supporting uric acid in the pathogenesis of metabolic syndrome. Fourth, environmental and genetic considerations provide a potential explanation of why certain groups might be more susceptible to developing diabetes. Finally, we discuss the counterarguments associated with the hypothesis and a potential explanation for these findings. If diabetes might result from excessive intake of fructose, then simple public health measures could have a major impact on improving the overall health of our populace.

The role of iron in type 2 diabetes in humans

The role of micronutrients in the etiology of type 2 diabetes is not well established. Several lines of evidence suggest that iron play may a role in the pathogenesis of type 2 diabetes. Iron is a strong pro-oxidant and high body iron levels are associated with increased level of oxidative stress that may elevate the risk of type 2 diabetes. Several epidemiological studies have reported a positive association between high body iron stores, as measured by circulating ferritin level, and the risk of type 2 diabetes and of other insulin resistant states such as the metabolic syndrome, gestational diabetes and polycystic ovarian syndrome. In addition, increased dietary intake of iron, especially that of heme iron, is associated with risk of type 2 diabetes in apparently healthy populations. Results from studies that have evaluated the association between genetic mutations related to iron metabolism have been inconsistent. Further, several clinical trials have suggested that phlebotomy induced reduction in body iron levels may improve insulin sensitivity in humans. However, no interventional studies have yet directly evaluated the effect of reducing iron intake or body iron levels on the risk of developing type 2 diabetes. Such studies are required to prove the causal relationship between moderate iron overload and diabetes risk.

Diet during early pregnancy and development of gestational diabetes

Diet composition may be a modifiable predictor of risk for abnormal glucose tolerance during pregnancy. Prior studies suggest that diets high in total fat, saturated fat, red and processed meats, and with high glycaemic load increase the risk of developing gestational diabetes mellitus (GDM), while polyunsaturated fats, carbohydrates and fibre are protective. The aim of this study was to investigate associations of these and other nutrients and foods, including n-3 fatty acids, trans fats, whole grains and dietary patterns, with risk of GDM. We studied 1733 women with singleton pregnancies enrolled in Project Viva, a prospective pregnancy and birth cohort study in eastern MA. Using multinomial logistic regression, we examined associations of first trimester diet, assessed by validated food frequency questionnaire, with results of glucose tolerance testing at 26-28 weeks of gestation. A total of 91 women developed GDM and 206 women had impaired glucose tolerance (IGT). Pre-pregnancy body mass index (BMI) was a strong predictor for GDM risk (OR 3.44 [95% CI 1.88, 6.31] for pre-pregnancy BMI > or =30 vs. <25 kg/m(2)). After adjustment for confounders, the OR [95% CI] for risk of GDM for total dietary fat was 1.00 [0.96, 1.05], for saturated fat 0.98 [0.88, 1.08], for polyunsaturated fat 1.09 [0.94, 1.26], for trans fat 0.87 [0.51, 1.49], and for carbohydrates 1.00 [0.96, 1.03] per each 1% of total energy. The adjusted OR [95% CI] for risk of GDM for a one standard deviation increase in energy-adjusted glycaemic load (32 units, about two soft drinks) was 0.96 [0.76, 1.22] and for each daily serving of whole grains was 0.90 [0.73, 1.13]. Dietary patterns and intake of red and processed meats were not predictive of glucose tolerance outcome. Estimates for IGT were similar to those for GDM. Intake of n-3 fatty acids was associated with increased GDM risk (OR 1.11 [95% CI 1.02, 1.22] per each 300 mg/day), but not with IGT risk. Except for this finding, perhaps due to chance, these data do not show that nutrient or food intake in early pregnancy is linked to risk of GDM. Nutritional status entering pregnancy, as reflected by pre-pregnancy BMI, is probably more important than pregnancy diet in development of GDM.

Protein, iron, and meat consumption and risk for rheumatoid arthritis: a prospective cohort study

A recent prospective study showed that higher consumption of red meat and total protein was associated with increased risk for inflammatory polyarthritis. We therefore prospectively examined the relationship between diet (in particular, protein, iron, and corresponding food sources) and incident rheumatoid arthritis (RA) among 82,063 women in the Nurses' Health Study. From 1980 to 2002, 546 incident cases of RA were confirmed by a connective tissue disease screening questionnaire and medical record review for American College of Rheumatology criteria for RA. Diet was assessed at baseline in 1980 and five additional times during follow up. We conducted Cox proportional hazards analyses to calculate the rate ratio of RA associated with intakes of protein (total, animal, and vegetable) and iron (total, dietary, from supplements, and heme iron) and their primary food sources, adjusting for age, smoking, body mass index, and reproductive factors. The multivariate models revealed no association between RA and any measure of protein or iron intake. In comparisons of highest with lowest quintiles of intake, the rate ratio for total protein was 1.17 (95% confidence interval 0.89–1.54; P for trend = 0.11) and for total iron it was 1.04 (95% confidence interval 0.77–1.41; P for trend = 0.82). Red meat, poultry, and fish were also not associated with RA risk. We were unable to confirm that there is an association between protein or meat and risk for RA in this large female cohort. Iron was also not associated with RA in this cohort.

Major dietary patterns in pregnancy and fetal growth

OBJECTIVES

To investigate possible associations between maternal diet during pregnancy and fetal growth.

METHOD

Factor analysis was used to explore dietary patterns among pregnant women. The association between maternal dietary patterns and fetal growth (in terms of small for gestational age, SGA) was investigated by logistic regression. Prospective cohort study, including information on 44 612 women in Denmark.

RESULTS

Two major dietary patterns were defined: the first pattern was characterized by red and processed meat, high-fat dairy, and the second pattern was characterized by intake of vegetables, fruits, poultry and fish. Women were classified into three classes according to their diet: the first class had high intake of foods of the first dietary pattern, and was classified as 'the Western diet', the second class preferred foods of the second pattern and was classified as the 'Health Conscious'; and the third one had eaten foods of both patterns, and was classified as the 'Intermediate'. The odds ratio of having a small for gestational-age infant (with a birth weight below the 2.5th percentile for gestational age and gender) was 0.74 (95% CI 0.64-0.86) for women in the Health Conscious class compared with women in the Western Diet class. The analyses were adjusted for parity, maternal smoking, age, height, pre-pregnancy weight and father's height.

CONCLUSIONS

Our results indicated that a diet in pregnancy, based on red and processed meat and high-fat diary, was associated with increased risk for SGA. Further studies are warranted to identify specific macro-, or micronutrients that may be underlying these associations.