Magnesium intake and risk of type 2 diabetes: a meta-analysis

OBJECTIVE: To assess the association between magnesium intake and risk of type 2 diabetes. DESIGN: Meta-analysis of prospective cohort studies. DATA SOURCES: We retrieved studies published in any language by systematically searching MEDLINE from 1966 to February 2007 and by manually examining the references of the original articles. STUDY SELECTION: We included prospective cohort studies reporting relative risks with 95% confidence intervals for the association between magnesium intake and incidence of type 2 diabetes. RESULTS: The seven identified cohort studies of magnesium intake [from foods only (n = 4) or from foods and supplements combined (n = 3)] and incidence of type 2 diabetes included 286,668 participants and 10,912 cases. All but one study found an inverse relation between magnesium intake and risk of type 2 diabetes, and in four studies the association was statistically significant. The overall relative risk for a 100 mg day(-1) increase in magnesium intake was 0.85 (95% CI, 0.79-0.92). Results were similar for intake of dietary magnesium (RR, 0.86; 95% CI, 0.77-0.95) and total magnesium (RR, 0.83; 95% CI, 0.77-0.89). There was no evidence of publication bias (P = 0.99). CONCLUSIONS: Magnesium intake was inversely associated with incidence of type 2 diabetes. This finding suggests that increased consumption of magnesium-rich foods such as whole grains, beans, nuts, and green leafy vegetables may reduce the risk of type 2 diabetes.     

Serum magnesium and the risk of prediabetes: a population-based cohort study

Aims/hypothesis

Previous studies have found an association between serum magnesium and incident diabetes; however, this association may be due to reverse causation, whereby diabetes may induce urinary magnesium loss. In contrast, in prediabetes (defined as impaired fasting glucose), serum glucose levels are below the threshold for urinary magnesium wasting and, hence, unlikely to influence serum magnesium levels. Thus, to study the directionality of the association between serum magnesium levels and diabetes, we investigated its association with prediabetes. We also investigated whether magnesium-regulating genes influence diabetes risk through serum magnesium levels. Additionally, we quantified the effect of insulin resistance in the association between serum magnesium levels and diabetes risk.

Methods

Within the population-based Rotterdam Study, we used Cox models, adjusted for age, sex, lifestyle factors, comorbidities, kidney function, serum levels of electrolytes and diuretic use, to study the association between serum magnesium and prediabetes/diabetes. In addition, we performed two mediation analyses: (1) to study if common genetic variation in eight magnesium-regulating genes influence diabetes risk through serum magnesium levels; and (2) to quantify the proportion of the effect of serum magnesium levels on diabetes that is mediated through insulin resistance (quantified by HOMA-IR).

Results

A total of 8555 participants (mean age, 64.7 years; median follow-up, 5.7 years) with normal glucose levels (mean?±?SD: 5.46?±?0.58 mmol/l) at baseline were included. A 0.1 mmol/l decrease in serum magnesium level was associated with an increase in diabetes risk (HR 1.18 [95% CI 1.04, 1.33]), confirming findings from previous studies. Of interest, a similar association was found between serum magnesium levels and prediabetes risk (HR 1.12 [95% CI 1.01, 1.25]). Genetic variation in CLDN19, CNNM2, FXYD2, SLC41A2, and TRPM6 significantly influenced diabetes risk (p?<?0.05), and for CNNM2, FXYD2, SLC41A2 and TRPM6 this risk was completely mediated by serum magnesium levels. We found that 29.1% of the effect of serum magnesium levels on diabetes was mediated through insulin resistance, whereas for prediabetes 13.4% was mediated through insulin resistance.

Conclusions/interpretation

Low serum magnesium levels are associated with an increased risk of prediabetes and this increased risk is similar to that of diabetes. Furthermore, common variants in magnesium-regulating genes modify diabetes risk through serum magnesium levels. Both findings support a potential causal role of magnesium in the development of diabetes, where the hypothesised pathway is partly mediated through insulin resistance.

     

Fiber and magnesium intake and incidence of type 2 diabetes: a prospective study and meta-analysis

BACKGROUND: Prospective studies on fiber and magnesium intake and risk of type 2 diabetes mellitus were inconsistent. We examined associations between fiber and magnesium intake and risk of type 2 diabetes and summarized existing prospective studies by meta-analysis. METHODS: We conducted a prospective cohort study of 9702 men and 15 365 women aged 35 to 65 years who were observed for incident diabetes from 1994 to 2005. Dietary intake of fiber and magnesium were measured with a validated food-frequency questionnaire. We estimated the relative risk (RR) by means of Cox proportional hazards analysis. We searched PubMed through May 2006 for prospective cohort studies of fiber and magnesium intake and risk of type 2 diabetes. We identified 9 cohort studies of fiber and 8 studies of magnesium intake and calculated summary RRs by means of a random-effects model. RESULTS: During 176 117 person-years of follow-up, we observed 844 incident cases of type 2 diabetes in the European Prospective Investigation Into Cancer and Nutrition-Potsdam. Higher cereal fiber intake was inversely associated with diabetes risk (RR for extreme quintiles, 0.72 [95% confidence interval [CI], 0.56-0.93]), while fruit fiber (0.89 [95% CI, 0.70-1.13]) and vegetable fiber (0.93 [95% CI, 0.74-1.17]) were not significantly associated. Meta-analyses showed a reduced diabetes risk with higher cereal fiber intake (RR for extreme categories, 0.67 [95% CI, 0.62-0.72]), but no significant associations for fruit (0.96 [95% CI, 0.88-1.04]) and vegetable fiber (1.04 [95% CI, 0.94-1.15]). Magnesium intake was not related to diabetes risk in the European Prospective Investigation Into Cancer and Nutrition-Potsdam (RR for extreme quintiles, 0.99 [95% CI, 0.78-1.26]); however, meta-analysis showed a significant inverse association (RR for extreme categories, 0.77 [95% CI, 0.72-0.84]). CONCLUSION: Higher cereal fiber and magnesium intakes may decrease diabetes risk.     

Serum uric acid and its change with the risk of type 2 diabetes: A prospective study in China

ObjectiveTo assess the association of baseline uric acid levels and their changes from baseline to Year 1 with the risk of type 2 diabetes.Research design and methodsThis study cohort included 9471 subjects without a history of diabetes at baseline. The incident diabetes was diagnosed according to the American Diabetes Association standard.ResultsDuring a mean follow-up of 2.9 years, we identified 762 type 2 diabetes cases. Multivariate-adjusted hazard ratios (HRs) of diabetes across baseline tertiles of serum uric acid were 1.00, 1.15, and 1.32 (P for trend = 0.018), respectively. Participants with hyperuricemia compared with those without had a 1.20-fold (95% confidence interval [CI] 1.01−1.44) risk of diabetes. When uric acid was examined as a continuous variable, multivariable-adjusted HR of diabetes for each 1 mg/dL (60 μmol/L) increase in serum uric acid was 1.09 (95% CI 1.03−1.15). Compared with subjects with stable serum uric acid from baseline to Year 1 (±10%), those with uric acid gain ≥30% had a 30% (95% CI 1.01–1.79) increased risk of diabetes and those with uric acid loss ≥10% had a 21% (95% 0.62−0.99) decreased risk of diabetes. This positive association between baseline serum uric acid and diabetes risk was consistent among subjects younger and older than 45 years, non-obese and obese participants, and men.ConclusionsHigh level of baseline serum uric acid and serum uric acid gain from baseline to Year 1 are associated with an increased risk of type 2 diabetes among Chinese adults.     

Adipocytokines and incident diabetes mellitus in older adults: the independent effect of plasminogen activator inhibitor 1

BACKGROUND: Adipose tissue produces "adipocytokines" of uncertain clinical significance. METHODS: We analyzed the relationships among adiposity, adipocytokines, glycemia, and incident diabetes mellitus in 2356 white and black adults aged 70 to 79 years in the Health, Aging, and Body Composition Study who did not have diabetes at baseline. We measured the levels of adipocytokines adiponectin, leptin, interleukin 6, tumor necrosis factor alpha, and plasminogen activator inhibitor 1. Regional fat area was determined by means of computed tomography. New diabetes was defined as a self-reported diagnosis of diabetes or as a fasting plasma glucose level of 126 mg/dL or greater (>/=7.0 mmol/L) at the second, fourth, or sixth annual examination. RESULTS: A total of 143 participants (14.1 cases per 1000 person-years) developed diabetes across 5 years. Visceral fat area (odds ratio [OR], 1.33; 95% confidence interval [CI], 1.10-1.60 per standard deviation increase) and body mass index (white individuals: OR, 1.65; 95% CI, 1.26-2.15 per standard deviation increase; black individuals: OR, 1.22; 95% CI, 0.99-1.51 per standard deviation increase) independently predicted incident diabetes. Adiponectin, leptin, and plasminogen activator inhibitor 1 attenuated the relationship between adiposity and diabetes. After controlling for body mass index, visceral fat, fasting glucose, fasting insulin, high-density lipoprotein cholesterol, triglycerides, and hypertension at baseline, plasminogen activator inhibitor 1 was the only adipocytokine independently associated with increased odds of diabetes (OR, 1.35; 95% CI, 1.01-1.81). Fasting glucose level at baseline remained a strong predictor of incident diabetes, whereas associations with body mass index and visceral fat were attenuated. CONCLUSIONS: Adipocytokines and glycemia partially account for the relationship between adiposity and risk of type 2 diabetes due to adiposity. Plasminogen activator inhibitor 1 may be a useful predictor of diabetes in addition to measurements of body fat.     

Low serum potassium levels and risk of type 2 diabetes: the Toranomon Hospital Health Management Center Study 1 (TOPICS 1)

Aims/hypothesis

Evidence has suggested that low serum potassium concentrations decrease insulin secretion, leading to glucose intolerance, and that hypokalaemia induced by diuretics increases the risk for diabetes in hypertensive individuals. However, no prospective study has investigated the association between serum potassium and the development of type 2 diabetes in a healthy cohort comprised of Asian individuals not being administered antihypertensive medications. This study aimed to investigate whether low serum potassium is associated with increased risk of type 2 diabetes in apparently healthy Japanese men.

Methods

We followed 4,409 Japanese men with no history of diabetes, use of antihypertensives, renal dysfunction or liver dysfunction (mean ± SD age, 48.4?±?8.4?years). Cox proportional hazards regression was used to estimate HRs for incident diabetes (fasting plasma glucose level ??7.0?mmol/l, HbA_1c ???6.5% or self-reported) including serum potassium concentration as either a categorical or a continuous variable.

Results

During a 5?year follow-up, 250 individuals developed type 2 diabetes. The lowest tertile of serum potassium (2.8?C3.9?mmol/l) was independently associated with the development of diabetes after adjustment for known predictors (HR 1.57 [95% CI, 1.15?C2.15]) compared with the highest tertile (4.2?C5.4?mmol/l). Every 0.5?mmol/l lower increment in the baseline serum potassium level was associated with a 45% (12?C87%) increased risk of diabetes.

Conclusions/interpretation

Mild to moderately low serum potassium levels, within the normal range and without frank hypokalaemia, could be predictive of type 2 diabetes in apparently healthy Japanese men.     

Coffee consumption and risk of type 2 diabetes mellitus: an 11-year prospective study of 28 812 postmenopausal women

BACKGROUND: Coffee intake may be associated with reduced risk of type 2 diabetes mellitus because of minerals, phytochemicals, and antioxidants in coffee, but the role of caffeine is unclear. Our objective was to examine the association between total, caffeinated, and decaffeinated coffee intake, as assessed by food frequency questionnaire at baseline, and risk of incident type 2 diabetes mellitus. METHODS: This prospective analysis of the Iowa Women's Health Study (1986-1997) included 28 812 postmenopausal women free of diabetes and cardiovascular disease in the general community. The main outcome measure was incident type 2 diabetes mellitus as determined by mailed questionnaire. RESULTS: Coffee intake was categorized as 0, less than 1, 1 to 3, 4 to 5, and 6 or more cups per day. During 11 years of follow-up, there were 1418 incident cases of diabetes. Relative risks (RRs) were adjusted for a variety of demographic, adiposity, and lifestyle measures. Compared with women who reported 0 cups of coffee per day, women who consumed 6 or more cups per day had a 22% lower risk (RR = 0.78; 95% confidence interval [CI], 0.61-1.01) of diabetes (P for linear trend across categories, .06). This association appeared to be largely explained by decaffeinated coffee (RR = 0.67; 95% CI, 0.42-1.08; P for trend, .006) rather than regular coffee (RR = 0.79; 95% CI, 0.59-1.05; P for trend, .90). Intake of magnesium and phytate did not explain these associations. Intakes of caffeine from all sources was not associated with risk of diabetes. CONCLUSION: Coffee intake, especially decaffeinated, was inversely associated with risk of type 2 diabetes mellitus in this cohort of postmenopausal women.     

Serum dehydroepiandrosterone levels are associated with lower risk of type 2 diabetes: the Rotterdam Study

Aims/hypothesis

Previous literature documents controversial results for the impact of dehydroepiandrosterone (DHEA) in glucose metabolism. We aimed to assess the associations between serum levels of DHEA and its main derivatives DHEA sulphate (DHEAS) and androstenedione, as well as the ratio of DHEAS to DHEA, and risk of type 2 diabetes.

Methods

We used data on serum levels of DHEA, DHEAS and androstenedione from 5189 middle-aged and elderly men and women from the prospective population-based Rotterdam Study. Type 2 diabetes was defined as a fasting blood glucose ≥7.0 mmol/l or a non-fasting blood glucose ≥11.1 mmol/l.

Results

During a median follow-up of 10.9 years, 643 patients with incident type 2 diabetes were identified. After adjusting for age, sex, cohort, fasting status, fasting glucose and insulin, and BMI, both serum DHEA levels (per 1 unit natural log-transformed, HR 0.76, 95% CI 0.67, 0.87) and serum DHEAS levels (per 1 unit natural log-transformed, HR 0.82, 95% CI 0.73, 0.92) were inversely associated with risk of type 2 diabetes in the total population. Further adjustment for alcohol, smoking, physical activity, prevalent cardiovascular disease, serum total cholesterol, use of lipid-lowering medications, systolic BP, treatment for hypertension, C-reactive protein, oestradiol and testosterone did not substantially affect the association between DHEA and incident type 2 diabetes (per 1 unit natural log-transformed, HR 0.80, 95% CI 0.65, 0.99), but abolished the association between DHEAS and type 2 diabetes. Androstenedione was not associated with risk of type 2 diabetes, nor was DHEAS to DHEA ratio.

Conclusions/interpretation

DHEA serum levels might be an independent marker of type 2 diabetes.

     

Serum bicarbonate and mortality in stage 3 and stage 4 chronic kidney disease

Summary

Background and objectives

The incidence and prevalence of metabolic acidosis increase with declining kidney function. We studied the associations of both low and high serum bicarbonate levels with all-cause mortality among stage 3 and 4 chronic kidney disease (CKD) patients.

Design, setting, participants, & measurements

We examined factors associated with low (<23 mmol/L) and high (>32 mmol/L) serum bicarbonate levels using logistic regression models and associations between bicarbonate and all-cause mortality using Cox-proportional hazard models, Kaplan–Meier survival curves, and time-dependent analysis.

Results

Out of 41,749 patients, 13.9% (n = 5796) had low and 1.6% (n = 652) had high serum bicarbonate levels. After adjusting for relevant covariates, there was a significant association between low serum bicarbonate and all-cause mortality (hazard ratio [HR] 1.23, 95% CI 1.16, 1.31). This association was not statistically significant among patients with stage 4 CKD and diabetes. The time-dependent analysis demonstrated a significant mortality risk associated with a decline from normal to low bicarbonate level (HR 1.59, 95% CI 1.49, 1.69). High serum bicarbonate levels were associated with death irrespective of the level of kidney function (HR 1.74, 95% CI 1.52, 2.00). When serum bicarbonate was examined as a continuous variable, a J-shaped relationship was noted between serum bicarbonate and mortality.

Conclusions

Low serum bicarbonate levels are associated with increased mortality among stage 3 CKD patients and patients without diabetes. High serum bicarbonate levels are associated with mortality in both stage 3 and stage 4 CKD patients.     

正常低浓度血镁与2型糖尿病的相关性研究

目的:探讨正常偏低浓度血镁与2型糖尿病的相关性。方法:2010年3月至7月对上海市嘉定区菊园新区2 515名40岁以上居民进行问卷调查,测量身高、体重、腰围、血压等,并进行口服葡萄糖耐量试验(OGTT),采血检测血清镁、胰岛素、肝功能、肾功能、空腹及OGTT 2 h血糖(2hPG)。分析人群血镁浓度与2型糖尿病患病风险的相关性。结果:①在血镁的参考范围内,2hPG、2 h胰岛素、总胆固醇、低密度脂蛋白胆固醇和三酰甘油在血镁四分位分组各组间差异有统计学意义(均趋势P<0.01);校正相关混杂因素后,3组2型糖尿病患病风险OR(95%CI)分别是1.11(0.75～1.66)、1.61(1.08～2.40)和3.22(2.23～4.64)(趋势P<0.01)。结论:上海郊区40岁以上人群中,正常的低血镁水平与2型糖尿病患病风险显著相关。     

Association between dietary meat consumption and incident type 2 diabetes: the EPIC-InterAct study

Aims/hypothesis

A diet rich in meat has been reported to contribute to the risk of type 2 diabetes. The present study aims to investigate the association between meat consumption and incident type 2 diabetes in the EPIC-InterAct study, a large prospective case-cohort study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

Methods

During 11.7 years of follow-up, 12,403 incident cases of type 2 diabetes were identified among 340,234 adults from eight European countries. A centre-stratified random subsample of 16,835 individuals was selected in order to perform a case-cohort design. Prentice-weighted Cox regression analyses were used to estimate HR and 95% CI for incident diabetes according to meat consumption.

Results

Overall, multivariate analyses showed significant positive associations with incident type 2 diabetes for increasing consumption of total meat (50 g increments: HR 1.08; 95% CI 1.05, 1.12), red meat (HR 1.08; 95% CI 1.03, 1.13) and processed meat (HR 1.12; 95% CI 1.05, 1.19), and a borderline positive association with meat iron intake. Effect modifications by sex and class of BMI were observed. In men, the results of the overall analyses were confirmed. In women, the association with total and red meat persisted, although attenuated, while an association with poultry consumption also emerged (HR 1.20; 95% CI 1.07, 1.34). These associations were not evident among obese participants.

Conclusions/interpretation

This prospective study confirms a positive association between high consumption of total and red meat and incident type 2 diabetes in a large cohort of European adults.     

Consumption of sweet beverages and type 2 diabetes incidence in European adults: results from EPIC-InterAct

Aims/hypothesis

Consumption of sugar-sweetened beverages has been shown, largely in American populations, to increase type 2 diabetes incidence. We aimed to evaluate the association of consumption of sweet beverages (juices and nectars, sugar-sweetened soft drinks and artificially sweetened soft drinks) with type 2 diabetes incidence in European adults.

Methods

We established a case–cohort study including 12,403 incident type 2 diabetes cases and a stratified subcohort of 16,154 participants selected from eight European cohorts participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. After exclusions, the final sample size included 11,684 incident cases and a subcohort of 15,374 participants. Cox proportional hazards regression models (modified for the case–cohort design) and random-effects meta-analyses were used to estimate the association between sweet beverage consumption (obtained from validated dietary questionnaires) and type 2 diabetes incidence.

Results

In adjusted models, one 336 g (12 oz) daily increment in sugar-sweetened and artificially sweetened soft drink consumption was associated with HRs for type 2 diabetes of 1.22 (95% CI 1.09, 1.38) and 1.52 (95% CI 1.26, 1.83), respectively. After further adjustment for energy intake and BMI, the association of sugar-sweetened soft drinks with type 2 diabetes persisted (HR 1.18, 95% CI 1.06, 1.32), but the association of artificially sweetened soft drinks became statistically not significant (HR 1.11, 95% CI 0.95, 1.31). Juice and nectar consumption was not associated with type 2 diabetes incidence.

Conclusions/interpretation

This study corroborates the association between increased incidence of type 2 diabetes and high consumption of sugar-sweetened soft drinks in European adults.     

Association between serum chloride levels with mortality in incident peritoneal dialysis patients

Background and aimsLower serum chloride (Cl) levels have been associated with excess mortality in pre-dialysis chronic kidney disease patients. However, the relationship between serum Cl levels and clinical outcomes in continuous ambulatory peritoneal dialysis (CAPD) patients is unclear.Methods and resultsIn this retrospective cohort study, we enrolled 1656 eligible incident patients undergoing CAPD from 2006 to 2013, and followed until December 2018. Cox regression analyses were used to examine the association between baseline and time-varying serum Cl levels and mortality. During a median follow-up of 46 months, 503 patients (30.4%) died. In analyses of baseline serum Cl, the adjusted hazard ratios (HR) for tertile 1 (<100.0 mmol/L), tertile 2 (100.0–103.0 mmol/L) versus tertile 3 (>103.0 mmol/L) were 2.34 [95% confidence interval (CI) 1.43–3.82] and 1.73 (95% CI 1.24–2.42) for all-cause mortality, 2.86 (95% CI 1.47–5.56) and 1.90 (95% CI 1.19–3.02) for cardiovascular disease (CVD) mortality, respectively. And a linear relationship was observed between serum Cl and mortality. Further, the inverse association between serum Cl and CVD mortality was particularly accentuated in the patients who were ≥50 years or with a history of diabetes. Similarly, lower time-varying serum Cl levels were also associated with a significant increased risk of all-cause and CVD death.ConclusionLower serum Cl levels predicted higher risk of all-cause and CVD mortality in CAPD patients.     

Urinary sodium and potassium excretion and the risk of type 2 diabetes: a prospective study in Finland

Aims/hypothesis No previous studies on the association between salt intake and the risk of type 2 diabetes have been reported. The aim of this study was to assess whether high salt intake, measured by 24-h urinary sodium excretion, is an independent risk factor for type 2 diabetes.Methods We followed prospectively 932 Finnish men and 1,003 women aged 35–64 years with complete data on 24-h urinary sodium and potassium excretion and other study parameters. Hazard ratios for the incidence of type 2 diabetes were estimated for different levels of 24-h urinary sodium and potassium excretion.Results During a mean follow-up of 18.1 years, there were 129 incident cases of type 2 diabetes. The multivariate-adjusted (age, sex, study year, body mass index, physical activity, systolic blood pressure, antihypertensive drug treatment, education, smoking and coffee, alcohol, fruit, vegetable, sausage, bread and saturated fat consumption) hazard ratio for diabetes for the highest vs combined lower quartiles of 24-h urinary sodium excretion was 2.05 (95% CI, 1.43–2.96). This positive association persisted in non-obese and obese subjects, in normotensive and hypertensive subjects, as well as in men and women. Potassium excretion was not associated with the risk of type 2 diabetes.Conclusions/interpretation High sodium intake predicted the risk of type 2 diabetes, independently of other risk factors including physical inactivity, obesity and hypertension. These results provide direct evidence of the harmful effects of high salt intake in the adult population, although the confounding effect of other dietary factors cannot be fully excluded.     

Dietary magnesium intake and risk of incident hypertension among middle-aged and older US women in a 10-year follow-up study

To assess the hypothesis that magnesium intake is beneficial in the primary prevention of hypertension, 28,349 female United States health professionals aged > or =45 years participating in the Women's Health Study (WHS), who initially reported normal blood pressure (systolic blood pressure <140 mm Hg, diastolic blood pressure <90 mm Hg, no history of hypertension or antihypertensive medications), were prospectively studied. A semi-quantitative food frequency questionnaire was used to estimate magnesium intake. During a median follow-up of 9.8 years, 8,544 women developed incident hypertension. After adjustment for age and randomized treatment, magnesium intake was inversely associated with the risk for developing hypertension; women in the highest quintile (median 434 mg/day) had a decreased risk for hypertension (relative risk 0.87, 95% confidence interval [CI] 0.81 to 0.93, p for trend <0.0001) compared with those in the lowest quintile (median 256 mg/day). This inverse association was attenuated but remained significant after further adjustment for known risk factors. In the fully adjusted model, the relative risks were 1.00 (95% CI 0.95 to 1.10), 1.02 (95% CI 0.95 to 1.10), 0.96 (95% CI 0.89 to 1.03), and 0.93 (95% CI 0.86 to 1.02) (p for trend = 0.03). Similar associations were observed for women who never smoked and reported no history of high cholesterol or diabetes at baseline. In conclusion, the results suggest that higher intake of dietary magnesium may have a modest effect on the development of hypertension in women.     

Intake of fruit, vegetables, and antioxidants and risk of type 2 diabetes: systematic review and meta-analysis

BACKGROUND: The public health recommendation is to consume five or more servings of fruit and vegetables daily, but the association between the intake of fruit and vegetables and the risk of type 2 diabetes is unclear. METHODS: To examine the association between the intake of fruit, vegetables, and antioxidants and the risk of type 2 diabetes, prospective cohort studies were sought, with measures of intakes at baseline and incident diabetes at follow-up. RESULTS: Five cohort studies of fruit and vegetables intake and the risk of diabetes were included, incorporating 167,128 participants and 4858 incident cases of type 2 diabetes, with a mean follow-up of 13 years. The relative risk of type 2 diabetes for consuming five or more servings of fruit and vegetables daily was 0.96 (95% CI, 0.79-1.17, P = 0.96), 1.01 (0.88-1.15, P = 0.88) for three or more servings of fruit, and 0.97 (0.86-1.10, P = 0.59) for three or more servings of vegetables. Nine cohort studies of antioxidant intake and the risk of diabetes were also identified, incorporating 139,793 participants and 8813 incident cases of type 2 diabetes, with a mean follow-up of 13 years. The pooled relative risk was 0.87 (0.79-0.98, P = 0.02) for the highest compared with the lowest antioxidant intake. CONCLUSIONS: The consumption of three or more daily servings of fruit or vegetables was not associated with a substantial reduction in the risk of type 2 diabetes. The intake of antioxidants was associated with a 13% reduction in risk, mainly attributed to vitamin E. These results are not supported by randomized, controlled trials of vitamin supplements, therefore the findings might not be causal, and the discrepancy remains unclear.     

Dietary patterns, meat intake, and the risk of type 2 diabetes in women

BACKGROUND: Although obesity is the most important risk factor for type 2 diabetes, evidence is emerging that certain foods and dietary factors may be associated with diabetes. To examine the association between major dietary patterns and risk of type 2 diabetes mellitus in a cohort of women. METHODS: We prospectively assessed the associations between major dietary patterns and risk of type 2 diabetes in women. Dietary information was collected in 1984, 1986, 1990, and 1994 from 69,554 women aged 38 to 63 years without a history of diabetes, cardiovascular disease, or cancer in 1984. We conducted factor analysis and identified 2 major dietary patterns: "prudent" and "Western." We then calculated pattern scores for each participant and examined prospectively the associations between dietary pattern scores and type 2 diabetes risks. RESULTS: The prudent pattern was characterized by higher intakes of fruits, vegetables, legumes, fish, poultry, and whole grains, while the Western pattern included higher intakes of red and processed meats, sweets and desserts, french fries, and refined grains. During 14 years of follow-up, we identified 2699 incident cases of type 2 diabetes. After adjusting for potential confounders, we observed a relative risk for diabetes of 1.49 (95% confidence interval [CI], 1.26-1.76, P for trend, <.001) when comparing the highest to lowest quintiles of the Western pattern. Positive associations were also observed between type 2 diabetes and red meat and other processed meats. The relative risk for diabetes for every 1-serving increase in intake is 1.26 (95% CI, 1.21-1.42) for red meat, 1.38 (95% CI, 1.23-1.56) for total processed meats, 1.73 (95% CI, 1.39-2.16) for bacon, 1.49 (95% CI, 1.04-2.11) for hot dogs, and 1.43 (95% CI, 1.22-1.69) for processed meats. CONCLUSION: The Western pattern, especially a diet higher in processed meats, may increase the risk of type 2 diabetes in women.     

Hard drinking water does not protect against cardiovascular disease: new evidence from the British Regional Heart Study.

BACKGROUND: It has been previously suggested that hard drinking water in general, and in particular high calcium and magnesium intake from drinking water, protect against cardiovascular disease. DESIGN: Prospective study of men from 24 British towns, with widely differing levels of hardness in drinking water. METHODS: A total of 7,735 men aged 40-59 years were recruited during 1978-1980. Estimates of town-level water hardness were available and tap water samples, taken from 947 participants who also answered a questionnaire about water consumption, were used to calculate individual calcium and magnesium intakes. Men were followed for incident of major coronary heart disease (CHD) and stroke, and CHD mortality for 25 years. RESULTS: Water hardness varied from 0.27 to 5.28 mmol/l in the 24 towns. A weak inverse association was found between water hardness and incidence of cardiovascular disease (CVD) [hazard ratio (HR), 0.96 per two-fold increase, 95% confidence interval (CI), 0.91-1.01, P=0.08 after adjustment for age and seven established coronary risk factors]. No association was observed with CHD incidence (adjusted HR, 0.99, 95% CI, 0.94-1.04, P=0.62) or mortality (adjusted HR, 0.96, 95% CI, 0.90-1.02, P=0.18). Individual magnesium intake showed a positive, rather than an inverse, association with CHD incidence (adjusted HR, 1.10 per two-fold increase, 95% CI, 1.01-1.20, P=0.045); individual calcium intake was unrelated to CHD or CVD end points. CONCLUSIONS: This study suggests that neither high water hardness, nor high calcium or magnesium intake appreciably protect against CHD or CVD. Initiatives to add calcium and magnesium to desalinated water cannot be justified by these findings.     

Glycemic index, glycemic load, and cereal fiber intake and risk of type 2 diabetes in US black women

BACKGROUND: Previous studies of carbohydrate quality and risk of type 2 diabetes mellitus have yielded inconsistent findings. Because diet is in part culturally determined, a study of dietary factors in US black women is of interest. METHODS: We used data from the Black Women's Health Study, a prospective cohort study of 59,000 US black women, to examine the association of glycemic load, glycemic index, and cereal fiber with risk of type 2 diabetes. Diet was assessed at baseline in 1995 with a modified version of the National Cancer Institute-Block food frequency questionnaire. RESULTS: During 8 years of follow-up, there were 1,938 incident cases of diabetes. Cox proportional hazards models were used to estimate incidence rate ratios (IRRs) for quintiles of dietary factors, while controlling for lifestyle and dietary factors. Glycemic index was positively associated with the risk of diabetes: the IRR for the highest quintile relative to the lowest was 1.23 (95% confidence interval [CI], 1.05-1.44). Cereal fiber intake was inversely associated with risk of diabetes, with an IRR of 0.82 (95% CI, 0.70-0.96) for the highest vs lowest quintiles of intake. Stronger associations were seen among women with a body mass index (calculated as weight in kilograms divided by height in meters squared) lower than 25: IRRs for the highest vs lowest quintile were 1.91 (95% CI, 1.16-3.16) for glycemic index (P value for interaction, .12) and 0.41 (95% CI, 0.24-0.72) for cereal fiber intake (P value for interaction, .05). CONCLUSION: Increasing cereal fiber in the diet may be an effective means of reducing the risk of type 2 diabetes, a disease that has reached epidemic proportions in black women.     

Insulin resistance influences the association of adiponectin levels with diabetes incidence in two population-based cohorts: the Cooperative Health Research in the Region of Augsburg (KORA) S4/F4 study and the Framingham Offspring Study

Aims/hypothesis

Lower adiponectin levels are associated with higher risk of incident type 2 diabetes. Most analyses have been adjusted for confounding factors, but few have taken into account insulin resistance per se. We tested the hypothesis that the association of adiponectin levels with incident type 2 diabetes differs between insulin-resistant and insulin-sensitive individuals.

Methods

We studied two prospective cohorts: the Framingham Offspring Study (n?=?2,023) and the Cooperative Health Research in the Region of Augsburg (KORA) S4/F4 study (n?=?887) cohorts. Insulin resistance was estimated by HOMA-insulin resistance (HOMA-IR). We used logistic regression analysis to test the association between adiponectin and incident type 2 diabetes overall and in insulin-resistant vs insulin-sensitive individuals (defined by ?? vs <75th percentile of HOMA-IR).

Results

At baseline, Framingham??s participants were 60?±?9?years old and 56% were women; KORA??s participants were 63?±?5?years old and 49% were women. Type 2 diabetes incidence was 5.4% over 6.5?years (n?=?109) in Framingham and 10.5% over 8?years (n?=?93) in KORA. Lower adiponectin levels were associated with type 2 diabetes incidence in both cohorts. In insulin-resistant individuals, lower adiponectin levels were associated with higher risk of type 2 diabetes incidence (OR 1.60 [95% CI 1.10?C2.31] per SD decrease in Framingham, p?=?0.01; and OR 2.34 [95% CI 1.16?C4.73] in KORA, p?=?0.02); while this was not observed in insulin-sensitive individuals (OR 1.10 [95% CI 0.73?C1.67] in Framingham, p?=?0.64; and OR 1.34 [95%CI: 0.88?C2.03] in KORA, p?=?0.18).

Conclusions/interpretation

We conclude that lower adiponectin levels are associated with higher risk of type 2 diabetes in insulin-resistant but not in insulin-sensitive individuals. This suggests that some level of insulin resistance is needed to see deleterious effects of low adiponectin.