Magnesium intake and risk of type 2 diabetes in men and women

Obesity, inflammation, and the potential application of pharmaconutrition

Obesity is an emerging problem worldwide. Hospitalized obese patients often have a worse outcome than patients of normal weight, particularly in the setting of trauma and critical care. Obesity creates a low-grade systemic inflammatory response syndrome (SIRS) that is similar (but on a much smaller scale) to gram-negative sepsis. This process involves up-regulation of systemic immunity, is characterized clinically by insulin resistance and the metabolic syndrome, and puts the patient at increased risk for organ failure, infectious morbidity, and mortality. Through lipotoxicity and cytokine dysregulation, obesity may act to prime the immune system, predisposing to an exaggerated subsequent immune response when a second clinical insult occurs (such as trauma, burns, or myocardial infarction). Specialized nutrition therapy for such patients currently consists of a hypocaloric, high-protein diet. However, this approach does not address the putative pathophysiologic mechanisms of inflammation and altered metabolism associated with obesity. A number of dietary agents such as arginine, fish oil, and carnitine may correct these problems at the molecular level. Pharmaconutrition formulas may provide exciting innovations for the nutrition therapy of the obese patient.

Vegetable but not fruit consumption reduces the risk of type 2 diabetes in Chinese women

We examined associations between fruit and vegetable intake and the incidence of type 2 diabetes (T2D) in a population-based prospective study of 64,191 women with no history of T2D or other chronic diseases at study recruitment and with valid dietary information. Dietary intake was assessed by in-person interviews using a validated FFQ. During 297,755 person-years of follow-up, 1608 new cases of T2D were documented. We used a Cox regression model to evaluate the association of fruit and vegetable intake (g/d) with the risk of T2D. Quintiles of vegetable intake and T2D were inversely associated. The relative risk for T2D for the upper quintile relative to the lower quintile of vegetable intake was 0.72 (95%CI: 0.61-0.85; P < 0.01) in multivariate analysis. Individual vegetable groups were all inversely and significantly associated with the risk of T2D. Fruit intake was not associated with the incidence of diabetes in this population. Our data suggest that vegetable consumption may protect against the development of T2D.

Mediterranean diet and metabolic diseases

PURPOSE OF REVIEW

The objective of this article is to present evidence illustrating the relationship between Mediterranean diets and metabolic diseases, including obesity, type 2 diabetes, and the metabolic syndrome, and to briefly discuss potential mechanisms by which these diets can help in disease prevention and treatment.

RECENT FINDINGS

Although the Mediterranean diet has long been celebrated for its impact on cardiovascular health, mounting evidence indicates a favorable effect on obesity and type 2 diabetes, as well. While health promotion strategies aimed at preventing adult obesity are emphasizing components of Mediterranean dietary patterns, a role for Mediterranean diets in attenuating the inflammatory burden associated with type 2 diabetes is also emerging. Moreover, a lower prevalence of the metabolic syndrome is associated with dietary patterns rich in fruits, vegetables, whole grains, dairy products, and unsaturated fats. Both epidemiological and interventional studies have revealed a protective effect of the Mediterranean diet against mild chronic inflammation and its metabolic complications.

SUMMARY

Mounting evidence suggests that Mediterranean diets could serve as an anti-inflammatory dietary pattern, which could help fighting diseases that are related to chronic inflammation, including visceral obesity, type 2 diabetes and the metabolic syndrome.

Transient receptor potential melastatin 6 and 7 channels, magnesium transport, and vascular biology: implications in hypertension

Magnesium, an essential intracellular cation, is critically involved in many biochemical reactions involved in the regulation of vascular tone and integrity. Decreased magnesium concentration has been implicated in altered vascular reactivity, endothelial dysfunction, vascular inflammation, and structural remodeling, processes important in vascular changes and target organ damage associated with hypertension. Until recently, very little was known about mechanisms regulating cellular magnesium homeostasis, and processes controlling transmembrane magnesium transport had been demonstrated only at the functional level. Two cation channels of the transient receptor potential melastatin (TRPM) cation channel family have now been identified as magnesium transporters, TRPM6 and TRPM7. These unique proteins, termed chanzymes because they possess a channel and a kinase domain, are differentially expressed, with TRPM6 being found primarily in epithelial cells and TRPM7 occurring ubiquitously. Vascular TRPM7 is modulated by vasoactive agents, pressure, stretch, and osmotic changes and may be a novel mechanotransducer. In addition to its magnesium transporter function, TRPM7 has been implicated as a signaling kinase involved in vascular smooth muscle cell growth, apoptosis, adhesion, contraction, cytoskeletal organization, and migration, important processes involved in vascular remodeling associated with hypertension and other vascular diseases. Emerging evidence suggests that vascular TRPM7 function may be altered in hypertension. This review discusses the importance of magnesium in vascular biology and implications in hypertension and highlights the transport systems, particularly TRPM6 and TRPM7, which may play a role in the control of vascular magnesium homeostasis. Since the recent identification and characterization of Mg2+-selective transporters, there has been enormous interest in the field. However, there is still a paucity of information, and much research is needed to clarify the exact mechanisms of magnesium regulation in the cardiovascular system and the implications of aberrant transmembrane magnesium transport in the pathogenesis of hypertension and other vascular diseases.

Orlistat in the prevention of diabetes in the obese patient

There has been an increase in the concern about preventing type 2 diabetes mellitus (T2DM), a disease with great and increasing prevalence. The prevalence of obesity, physical inactivity, Western processed diet, important risk factors for the development of T2DM, are also rising. Free fatty acids are increased in obesity and reduce insulin clearance and increase hepatic glucose production. Implementation of a healthy lifestyle has been show to slow the progression of impaired glucose tolerance to T2DM. Orlistat is an inhibitor of lipase activity, with proved efficacy in body weight reduction and long-term management of obesity and more favorable effects on carbohydrate metabolism and it was prospectively shown in XENDOS study that orlistat promoted long-term weight loss and prevented T2DM onset in obese individuals with normal and impaired glucose tolerance at baseline over four years. This benefit could be associated to the weight loss itself, to the limited absorption of lipids and reduction of plasma free fatty acids, to increased production of incretins or to modulation of secretion of cytokines by adipocytes, all effects secondary to orlistat treatment. A proposed strategy is to identify subjects at highest risk to receive a drug intervention, using lifestyle interventions alone at the community level.

Magnesium intake, glucose and insulin serum levels in pre-school very-low-birth weight pre-term children

AIMS

To evaluate cross-sectional associations between dietary magnesium intake and the metabolic pattern of very-low-birth-weight (VLBW, <1500 g) pre-term children, in pre-school years (>2 and <6 years).

METHODS AND RESULTS

Fifty-eight Italian children without major congenital malformations/conditions were enrolled; dietary intakes, clinical and (in 34 cases) laboratory characteristics were evaluated. Subjects with lower magnesium intake showed significantly higher fasting glucose, insulin and Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) levels. At simple regression analysis, fasting glucose was significantly associated with magnesium intake (inversely) and catch-up growth (CUG). Fasting insulin and HOMA-IR values were inversely associated with intakes of magnesium and fibres, and directly with Body Mass Index (BMI) and CUG. In a multiple regression model, after adjusting for multiple confounders and fibre intake, magnesium intake was inversely associated with glucose (beta=-0.018; 95%CI -0.026 to -0.010), but not with insulin or HOMA-IR levels. In the same model, dietary fibres remained inversely associated with insulin (beta=-0.075; -0.14 to -0.008) and HOMA-IR levels (beta=-0.06; -0.11 to -0.01).

CONCLUSION

These results suggest a significant association between reduced magnesium intake and fasting glucose, and between reduced fibre intake and insulin resistance and this is present even in earlier childhood, and independently of BMI and growth characteristics.

Magnesium metabolism in hypertension and type 2 diabetes mellitus

The increasing evidence for the clinical relevance of altered magnesium metabolism to states of altered insulin resistance confirms the role of magnesium deficit as a possible underlying common mechanism of the "insulin resistance" of hypertension and altered glucose tolerance. The pioneer work of Lawrence M. Resnick and his group using the cellular ion-based approach that we are only partially presenting here has consistently contributed to the progress of the field, demonstrating (a) the critical importance of magnesium metabolism in regulating insulin sensitivity as well as vascular tone, and blood-pressure homeostasis; (b) that magnesium deficiency, defined on the basis of intracellular free magnesium levels, and or serum ionized magnesium is a common feature of both diabetic and hypertensive states as well as various other cardiovascular and metabolic processes and aging; (c) the ability of environmental factors such as dietary nutrient-sugar and mineral content to alter the set point of steady-state cell ion activity; and (d) that magnesium supplementation is indicated in conditions associated with magnesium deficit although well-designed therapeutic trials of magnesium in essential hypertension and type 2 diabetes mellitus are needed in the near future.

Characteristics of adults with and without cystic fibrosis-related diabetes

AIMS

The prevalence of diabetes in adults with cystic fibrosis (CF) approximates 25%, yet few studies have defined risk factors. We examined the association between biochemical and clinical factors and CF-related diabetes.

METHODS

We performed a study in adults with CF in 2004 in Cambridgeshire, UK. Of 160 individuals, 51 had diabetes (cases) on the basis of medical history or screening using a 75-g oral glucose tolerance test, and 107 did not have diabetes (control subjects); two were excluded. We used logistic regression to model the cross-sectional association between potential risk factors and diabetes.

RESULTS

The mean age was 26 (16-58) years, mean body mass index (BMI) was 21 (16-28) kg/m(2), and mean forced expiratory volume in 1 s was 60 +/- 24% (mean +/- sd). All of the cases and 88% of control subjects had pancreatic insufficiency. Cases did not differ from control subjects with respect to age, sex, body mass index, or dose of oral pancreatic enzymes. Cases were more likely to have low serum magnesium, haemoglobin, and pulmonary function, and higher serum gamma-glutamyl transferase (GGT) activity, plasma fibrinogen levels, erythrocyte sedimentation rate, use of oral corticosteroids, and number of CF-related complications. In multivariate analyses, GGT, previous organ transplantation, plasma fibrinogen and the presence of CF-related complications were independently associated with diabetes, after controlling for corticosteroid use.

CONCLUSIONS

These data confirm the high prevalence of diabetes in adults with CF, and identify plasma fibrinogen and GGT, and organ transplantation as factors independently associated with CF-related diabetes. A prospective study would clarify the nature of these associations.

Association of serum caffeine concentrations with serum glucose levels in caffeine-drug users and non-users - results of German National Health Surveys

The purpose of this study was to explore the association of serum caffeine concentrations with serum glucose levels in caffeine-drug users and non-users, aiming at the chronic effects of caffeine on glucose metabolism in comparison with known acute effects of caffeine. Eight hundred and fourteen caffeine-drug users and 623 non-users were identified from German National Health Surveys. Their serum caffeine concentrations and glucose levels were measured. The associations of caffeine concentrations with glucose levels were established by correlation analysis and multivariable regression analysis in caffeine-drug users and non-users separately. Antidiabetic therapy was considered. Caffeine concentrations were closely positively correlated to serum glucose levels in caffeine-drug users (Spearman r = 0.117, p = 0.001; partial r = 0.102, p = 0.020) particularly in women (Spearman r = 0.155, p < 0.001; partial r = 0.150, p = 0.005) although the correlation was weak as shown by multivariable regression analysis. The serum glucose levels were significantly higher (5.403 +/- 0.033 vs. 5.306 +/- 0.037 mmol/l) whereas the magnesium level was significantly lower (0.8941 +/- 0.0026 vs. 0.9024 +/- 0.0030 mmol/l) in caffeine-drug users than in non-users. No associations of caffeine concentrations with serum glucose levels were found in any groups of caffeine-drug non-users in our study. Whereas acute intake of caffeine-drugs may impair glucose metabolism, chronic intake of caffeine exclusively from diet has little effects on glucose metabolism and therefore may not contribute to the risk reduction of type 2 diabetes that was found in recent coffee consumption studies.

The relation of magnesium and calcium intakes and a genetic polymorphism in the magnesium transporter to colorectal neoplasia risk

BACKGROUND

Mean magnesium intake in the US population does not differ from that in East Asian populations with traditionally low risks of colorectal cancer and other chronic diseases, but the ratio of calcium to magnesium (Ca:Mg) intake is much higher in the US population. Transient receptor potential melastatin 7 (TRPM7) is a newly found gene essential to magnesium absorption and homeostasis.

OBJECTIVE

We aimed to test whether the association of colorectal polyps with intake of calcium, magnesium, or both and Thr1482Ile polymorphism in the TRPM7 gene is modified by the Ca:Mg intake.

DESIGN

Included in the study were a total of 688 adenoma cases, 210 hyperplastic polyp cases, and 1306 polyp-free controls from the Tennessee Colorectal Polyp Study.

RESULTS

We found that total magnesium consumption was linked to a significantly lower risk of colorectal adenoma, particularly in those subjects with a low Ca:Mg intake. An inverse association trend was found for hyperplastic polyps. We also found that the common Thr1482Ile polymorphism was associated with an elevated risk of both adenomatous and hyperplastic polyps. Moreover, this polymorphism significantly interacted with the Ca:Mg intake in relation to both adenomatous and hyperplastic polyps. The subjects who carried >or=1 1482Ile allele and who consumed diets with a high Ca:Mg intake were at a higher risk of adenoma (odds ratio: 1.60; 95% CI: 1.12, 2.29) and hyperplastic polyps (odds ratio: 1.85; 95% CI: 1.09, 3.14) than were the subjects who did not carry the polymorphism.

CONCLUSION

These findings, if confirmed, may provide a new avenue for the personalized prevention of magnesium deficiency and, thus, colorectal cancer.

The effect of adverse housing and neighborhood conditions on the development of diabetes mellitus among middle-aged African Americans

The authors examined the associations of observed neighborhood (block face) and housing conditions with the incidence of diabetes by using data from 644 subjects in the African-American Health Study (St. Louis area, Missouri). They also investigated five mediating pathways (health behavior, psychosocial, health status, access to medical care, and sociodemographic characteristics) if significant associations were identified. The external appearance of the block the subjects lived on and housing conditions were rated as excellent, good, fair, or poor. Subjects reported about neighborhood desirability. Self-reported diabetes was obtained at baseline and 3 years later. Of 644 subjects without self-reported diabetes, 10.3% reported having diabetes at the 3-year follow-up. Every housing condition rated as fair-poor was associated with an increased risk of diabetes, with odds ratios ranging from 2.53 (95% confidence interval: 1.47, 4.34 for physical condition inside the building) to 1.78 (95% confidence interval: 1.03, 3.07 for cleanliness inside the building) in unadjusted analyses. No association was found between any of the block face conditions or perceived neighborhood conditions and incident diabetes. The odds ratios for the five housing conditions were unaffected when adjusted for the mediating pathways. Poor housing conditions appear to be an independent contributor to the risk of incident diabetes in urban, middle-aged African Americans.

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.

A prospective study of overall diet quality and risk of type 2 diabetes in women

OBJECTIVE

The aim of this article was to assess the association between the Alternate Healthy Eating Index (AHEI) and risk of type 2 diabetes in women.

RESEARCH DESIGN AND METHODS

A total of 80,029 women aged 38-63 years in the Nurses' Health Study were followed from 1984 to 2002. The AHEI score was computed from dietary information collected from five repeated food frequency questionnaires administered between 1984 and 1998. Relative risks (RRs) for type 2 diabetes were calculated using Cox proportional hazards models and adjusted for known diabetes risk factors. We also examined how changes in score in 4, 6-8, and 10-12 years are associated with diabetes risk.

RESULTS

We ascertained 5,183 incident cases of type 2 diabetes during 18 years of follow-up. Women who scored high on the AHEI had a lower risk (RR comparing top to bottom score quintile 0.64 [95% CI 0.58-0.71], P(trend) < 0.0001) for diabetes. Women with consistently high AHEI scores throughout follow-up, compared with those with consistently low scores, had the lowest risk for diabetes. In addition, women whose AHEI scores improved during follow-up, even during recent years, had a lower risk of diabetes than did women whose (low) score did not change.

CONCLUSIONS

A higher AHEI score is associated with a lower risk of type 2 diabetes in women. Therefore, the AHEI score may be a useful clinical tool to assess diet quality and to recommend for the prevention of diabetes.

Other relevant components of nuts: phytosterols, folate and minerals

Nuts contain significant amounts of essential micronutrients that are associated with an improved health status when consumed at doses beyond those necessary to prevent deficiency states. Nuts do not contain cholesterol, but they are rich in chemically related phytosterols, a class of compounds that interfere with intestinal cholesterol absorption and thus help lower blood cholesterol. Nuts also contain folate, a B-vitamin necessary for normal cellular function that plays an important role in detoxifying homocysteine, a sulphur-containing amino acid with atherothrombotic properties that accumulates in plasma when folate status is subnormal. Compared to other common foodstuffs, nuts have an optimal nutritional density with respect to healthy minerals, such as calcium, magnesium and potassium. Like that of most vegetables, the sodium content of nuts is very low. A high intake of calcium, magnesium and potassium, together with a low sodium intake, is associated with protection against bone demineralisation, arterial hypertension, insulin resistance, and overall cardiovascular risk. Phytosterols might justify part of the cholesterol-lowering effect of nut intake beyond that attributable to fatty acid exchange, while the mineral richness of nuts probably contributes to the prevention of diabetes and coronary heart disease observed in epidemiological studies in association with frequent nut consumption.

Nuts, body weight and insulin resistance

Traditionally, nuts have been considered a staple food, but because of their high energy and fat content are not considered good for body weight control or insulin sensitivity. Frequent consumption of nuts reduces the risk of coronary artery disease and type-2 diabetes and nut-enriched diets favourably alter blood lipids in normal and hypercholesterolemic individuals under controlled and free-living dietary conditions. However, whether or not frequent consumption of nuts can cause weight gain and impair insulin sensitivity is not fully understood. Review of the available data to date suggests that adding nuts to habitual diets of free-living individuals does not cause weight gain. In fact, nuts have a tendency to lower body weight and fat mass. In the context of calorie-restricted diets, adding nuts produces a more lasting and greater magnitude of weight loss among obese subjects while improving insulin sensitivity. Further studies are needed to clarify the effect of long-term (>/= year) consumption of nuts on body weight and their role in altering insulin sensitivity both in normal and type-2 diabetics. In the meantime, there is sufficient evidence to promote the inclusion of nuts as part of healthy diets.

Dietary fibre, nuts and cardiovascular diseases

Dietary fibre has a range of metabolic health benefits. Through a variety of mechanisms, dietary fibre, and the viscous variety in particular, slows down gastric emptying and intestinal transit, decreases the rate of intestinal carbohydrate absorption, and increases faecal bile acid excretion. Therefore, consumption of some types of soluble fibre can enhance satiety, which is associated with a lower BMI, and reduce blood cholesterol and the postprandial glucose response. Surprisingly, the consumption of insoluble fibre from whole grains, though metabolically inert, has been associated with a reduction in the risk of developing coronary heart disease and diabetes in epidemiological studies. The likely reason is that whole grains, like nuts, legumes and other edible seeds, contain many bioactive phytochemicals and various antioxidants. After cereals, nuts are the vegetable foods that are richest in fibre, which may partly explain their benefit on the lipid profile and cardiovascular health.

Nutritional strategies in the prevention and treatment of metabolic syndrome

The metabolic syndrome (MetS) is a clustering of metabolic abnormalities that increase the risk of developing atherosclerotic cardiovascular disease and type 2 diabetes. The exact etiology remains unclear, but it is known to be a complex interaction between genetic, metabolic, and environmental factors. Among environmental factors, dietary habits are of central importance in the prevention and treatment of this condition. However, there is currently no firm consensus on the most appropriate dietary recommendations. General recommendations include decreasing obesity, increasing physical activity, and consuming an anti-atherogenic diet, and have traditionally focused on low total fat intake. A major problem with the focus on low fat is that high-carbohydrate diets can contribute to increasing triglyceride and decreasing high-density lipoprotein (HDL) concentrations. Low-carbohydrate diets have been popular in recent years. However, such diets are typically higher in saturated fat and lower in fruits, vegetables, and whole grains than national dietary recommendations. More recently the quality of carbohydrate has been studied in relation to MetS, including a focus on dietary fiber and glycemic index. Similarly, there has been a move from limiting total fat to a focus on the quality of the fat, with evidence of beneficial effects of replacing some carbohydrate with monounsaturated fat. Other nutrients examined for possible importance include calcium, vitamin D, and magnesium. Together, the evidence suggests that the components of diet currently recommended as "healthy" are likely also protective against MetS, including low saturated and trans fat (rather than low total fat) and balanced carbohydrate intake rich in dietary fiber, as well as high fruit and vegetable intake (rather than low total carbohydrate); and the inclusion of low-fat dairy foods. Accelerating research on gene-diet interactions is likely to contribute interesting information that may lead to further individualized dietary guidance in the future.

[Association between dietary carbohydrates and type 2 diabetes mellitus: epidemiological evidence]

The prevalence of type 2 diabetes has been escalating throughout the world and usual food consumption is regarded as one of the most important environmental determinants for chronic diseases. Thus, the role of type and quality of carbohydrates on the etiology of type 2 diabetes is still poorly understood. The present review discusses the available epidemiological evidence regarding the effect of the type and source of carbohydrate of the usual diet and the risk of type 2 diabetes in adults. Although epidemiological investigations support the hypothesis for a potential risk effect of high glycemic index and low fiber content diets for diabetes, the results are controversial and the benefit may be related to the magnesium content of the structure of the grains, suggesting the relevance of taking into account the food sources instead of nutrients on investigations of diet and risk of chronic diseases. The available evidence suggests that eating a diet rich in whole grain cereals and vegetables and low in refined grains, sucrose and fructose contents is beneficial in the prevention of diabetes. Thus, more clinical trials are required to support the associations and establish biologically plausible pathways.

Magnesium metabolism in type 2 diabetes mellitus, metabolic syndrome and insulin resistance

Type 2 diabetes is characterized by cellular and extracellular Mg depletion. Epidemiologic studies showed a high prevalence of hypomagnesaemia and lower intracellular Mg concentrations in diabetic subjects. Insulin and glucose are important regulators of Mg metabolism. Intracellular Mg plays a key role in regulating insulin action, insulin-mediated-glucose uptake and vascular tone. Reduced intracellular Mg concentrations result in a defective tyrosine-kinase activity, post-receptorial impairment in insulin action, and worsening of insulin resistance in diabetic patients. Mg deficit has been proposed as a possible underlying common mechanism of the "insulin resistance" of different metabolic conditions. Low dietary Mg intake is also related to the development of type 2 diabetes. Benefits of Mg supplementation on metabolic profile in diabetic subjects have been found in most, but not all clinical studies, and larger prospective studies are needed to support the potential role of dietary Mg supplementation as a possible public health strategy in diabetes risk.

Hypomagnesemia in patients with type 2 diabetes

Hypomagnesemia has been reported to occur at an increased frequency among patients with type 2 diabetes compared with their counterparts without diabetes. Despite numerous reports linking hypomagnesemia to chronic diabetic complications, attention to this issue is poor among clinicians. This article reviews the literature on the metabolism of magnesium, incidence of hypomagnesemia in patients with type 2 diabetes, implicated contributing factors, and associated complications. Hypomagnesemia occurs at an incidence of 13.5 to 47.7% among patients with type 2 diabetes. Poor dietary intake, autonomic dysfunction, altered insulin metabolism, glomerular hyperfiltration, osmotic diuresis, recurrent metabolic acidosis, hypophosphatemia, and hypokalemia may be contributory. Hypomagnesemia has been linked to poor glycemic control, coronary artery diseases, hypertension, diabetic retinopathy, nephropathy, neuropathy, and foot ulcerations. The increased incidence of hypomagnesemia among patients with type 2 diabetes presumably is multifactorial. Because current data suggest adverse outcomes in association with hypomagnesemia, it is prudent to monitor magnesium routinely in this patient population and treat the condition whenever possible.

Dietary magnesium and fiber intakes and inflammatory and metabolic indicators in middle-aged subjects from a population-based cohort

BACKGROUND

Type 2 diabetes (DM), metabolic syndrome (MetS), and inflammation are linked to reduced magnesium and fiber intakes; these associations are attenuated by adjustment for each of these nutrients.

OBJECTIVE

We investigated the association among magnesium and fiber intakes, metabolic variables, and high-sensitivity C-reactive protein (hs-CRP) values.

DESIGN

Cross-sectional analyses were performed in a representative cohort of 1653 adults and in a subgroup with normal body mass index without dysmetabolisms (n = 205). A validated semiquantitative food-frequency questionnaire was used; magnesium intake was computed by multiplying its content in each food by the frequency of food consumption.

RESULTS

The prevalence of DM, MetS, and hs-CRP >/= 3 mg/L significantly decreased from the lowest to the highest tertile of magnesium and fiber intakes. Subjects within the lowest tertiles of magnesium and fiber intakes were 3-4 times as likely to have DM, MetS, and hs-CRP >/= 3 mg/L, after multiple adjustments. After the analysis was additionally controlled for fiber intake, associations with hs-CRP >/= 3 mg/L proved to be significant (odds ratio: 2.05; 95% CI: 1.30, 3.25), whereas reduced magnesium intake and DM and MetS were no longer significant. The lowest tertile of fiber intake remained associated with DM, hs-CRP >/= 3 mg/L, and MetS after adjustments for multiple confounders and magnesium intake. In the lean, healthy subject subgroup, hs-CRP values were inversely associated with magnesium and fiber intakes in a multivariate model (P < 0.001).

CONCLUSIONS

Reduced fiber intake was significantly associated with metabolic abnormalities; the magnesium effect might be confounded by fiber being in foods that also provided magnesium. Lower magnesium and fiber intakes were linked to hs-CRP >/= 3 mg/L in both the entire cohort and healthy persons.

Coffee, diabetes, and weight control

Several prospective epidemiologic studies over the past 4 y concluded that ingestion of caffeinated and decaffeinated coffee can reduce the risk of diabetes. This finding is at odds with the results of trials in humans showing that glucose tolerance is reduced shortly after ingestion of caffeine or caffeinated coffee and suggesting that coffee consumption could increase the risk of diabetes. This review discusses epidemiologic and laboratory studies of the effects of coffee and its constituents, with a focus on diabetes risk. Weight loss may be an explanatory factor, because one prospective epidemiologic study found that consumption of coffee was followed by lower diabetes risk but only in participants who had lost weight. A second such study found that both caffeine and coffee intakes were modestly and inversely associated with weight gain. It is possible that caffeine and other constituents of coffee, such as chlorogenic acid and quinides, are involved in causing weight loss. Caffeine and caffeinated coffee have been shown to acutely increase blood pressure and thereby to pose a health threat to persons with cardiovascular disease risk. One short-term study found that ground decaffeinated coffee did not increase blood pressure. Decaffeinated coffee, therefore, may be the type of coffee that can safely help persons decrease diabetes risk. However, the ability of decaffeinated coffee to achieve these effects is based on a limited number of studies, and the underlying biological mechanisms have yet to be elucidated.

Dietary calcium and magnesium, major food sources, and risk of type 2 diabetes in U.S. black women

OBJECTIVE

Inverse associations between magnesium and calcium intakes and risk of type 2 diabetes have been reported for studies in predominantly white populations. We examined magnesium, calcium, and major food sources in relation to type 2 diabetes in African-American women.

RESEARCH DESIGN AND METHODS

This is a prospective cohort study including 41,186 participants of the Black Women's Health Study without a history of diabetes who completed validated food frequency questionnaires at baseline. During 8 years of follow-up (1995-2003), we documented 1,964 newly diagnosed cases of type 2 diabetes.

RESULTS

The multivariate-adjusted hazard ratio of type 2 diabetes for the highest compared with the lowest quintile of intake was 0.69 (95% CI 0.59-0.81; P trend <0.0001) for dietary magnesium and 0.86 (0.74-1.00; P trend = 0.01) for dietary calcium. After mutual adjustment, the association for calcium disappeared (hazard ratio 1.04 [95% CI 0.88-1.24]; P trend = 0.88), whereas the association for magnesium remained. Daily consumption of low-fat dairy (0.87 [0.76-1.00]; P trend = 0.04) and whole grains (0.69 [0.60-0.79]; P trend <0.0001) were associated with a lower risk of type 2 diabetes compared with a consumption less than once a week. After mutual adjustment, the hazard ratio was 0.81 (0.68-0.97; P trend = 0.02) for magnesium and 0.73 (0.63-0.85; P trend <0.0001) for whole grains.

CONCLUSIONS

These findings indicate that a diet high in magnesium-rich foods, particularly whole grains, is associated with a substantially lower risk of type 2 diabetes in U.S. black women.

Dairy, magnesium, and calcium intake in relation to insulin sensitivity: approaches to modeling a dose-dependent association

Dairy intake has been inversely associated with insulin resistance, which may be partly due to the specific effects of calcium and magnesium. Data from the Insulin Resistance Atherosclerosis Study (1992-1999) for 1,036 US adults without diabetes at baseline were examined to evaluate the cross-sectional association of habitual dairy, magnesium, and calcium intake with insulin sensitivity at baseline and after 5 years of follow-up. Insulin sensitivity was directly measured with a validated, 12-sample, insulin-enhanced, intravenous glucose tolerance test with minimal model analysis. Dietary intake was assessed by a validated food frequency interview, and dietary supplement dose was confirmed by reviewing the supplement label. Several statistical approaches were used to ensure appropriate modeling of the dose-dependent association. No association was found between dairy intake and insulin sensitivity (p=0.41); however, associations were positive for magnesium and calcium intake (p=0.016) after adjusting for demographic, nondietary lifestyle and dietary factors, and food groups. Furthermore, magnesium intake was associated with insulin sensitivity in a threshold fashion, with a Bayesian method-estimated threshold (325 mg) (beta=0.0607/100 mg, p=0.0008 for <325 mg of magnesium/day; and beta=-0.001/100 mg, p=0.82 for >or=325 mg of magnesium/day). This study suggests that magnesium and calcium intake specifically, but not dairy intake, is associated with insulin sensitivity.

Coffee and health: a review of recent human research

Coffee is a complex mixture of chemicals that provides significant amounts of chlorogenic acid and caffeine. Unfiltered coffee is a significant source of cafestol and kahweol, which are diterpenes that have been implicated in the cholesterol-raising effects of coffee. The results of epidemiological research suggest that coffee consumption may help prevent several chronic diseases, including type 2 diabetes mellitus, Parkinson's disease and liver disease (cirrhosis and hepatocellular carcinoma). Most prospective cohort studies have not found coffee consumption to be associated with significantly increased cardiovascular disease risk. However, coffee consumption is associated with increases in several cardiovascular disease risk factors, including blood pressure and plasma homocysteine. At present, there is little evidence that coffee consumption increases the risk of cancer. For adults consuming moderate amounts of coffee (3-4 cups/d providing 300-400 mg/d of caffeine), there is little evidence of health risks and some evidence of health benefits. However, some groups, including people with hypertension, children, adolescents, and the elderly, may be more vulnerable to the adverse effects of caffeine. In addition, currently available evidence suggests that it may be prudent for pregnant women to limit coffee consumption to 3 cups/d providing no more than 300 mg/d of caffeine to exclude any increased probability of spontaneous abortion or impaired fetal growth.

Magnesium and diabetes mellitus: Their relation

The aim of this review was to elaborate a synthesis about the discussions on magnesium and diabetes mellitus, in the last 14 years. The magnesium deficiency has been associated with chronic diseases, amongst them, diabetes mellitus. Epidemiological studies had shown low levels of magnesium ingestion in the general population, as well as a relation between the ingestion of food rich in magnesium and the reduction of diabetes installation and its complications. Hypomagnesemia is frequently present in diabetic patients, however there is not an exact elucidation of the mechanism of magnesium deficiency in diabetes mellitus. On the other hand, in the presence of this illness, it is observed that inadequate metabolic control can affect the corporal concentrations of magnesium, developing hypomagnesemia, which may be still directly related with some micro and macrovascular complications observed in diabetes, as cardiovascular disease, retinopathy and neuropathy. This way, the chronic complications of diabetes can appear precociously. Based on this, the supplementation with magnesium has been suggested in patients with diabetes mellitus who have proven hypomagnesemia and the presence of its complications.

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.

Role of magnesium in hypertension

Magnesium affects blood pressure by modulating vascular tone and reactivity. It acts as a calcium channel antagonist, it stimulates production of vasodilator prostacyclins and nitric oxide and it alters vascular responses to vasoactive agonists. Magnesium deficiency has been implicated in the pathogenesis of hypertension with epidemiological and experimental studies demonstrating an inverse correlation between blood pressure and serum magnesium levels. Magnesium also influences glucose and insulin homeostasis, and hypomagnesemia is associated with metabolic syndrome. Although most epidemiological and experimental studies support a role for low magnesium in the pathophysiology of hypertension, data from clinical studies have been less convincing. Furthermore, the therapeutic value of magnesium in the management of hypertension is unclear. The present review addresses the role of magnesium in the regulation of vascular function and blood pressure and discusses the implications of magnesium deficiency in experimental and clinical hypertension, in metabolic syndrome and in pre-eclampsia.

Selection of antihypertensive agents in patients at risk for diabetes

Type 2 diabetes mellitus (DM2) has increased 41% in the United States, with an estimated one third undiagnosed and another 41 million with prediabetes. Hypertension affects 20% to 60% of all diabetics, contributing to up to 75% of deaths due to cardiovascular disease. These staggering statistics make it imperative that hypertensive patients who are at risk for DM2 are identified and treated early. Numerous studies have been done involving choice of antihypertensive in established diabetics, and a slowing or halting of the progression in the development of diabetes in these patients has been noticed. However, to date, nothing is conclusive. For now, following the JNC 7 guidelines of using a diuretic as monotherapy or in combination with an angiotensin-converting enzyme inhibitor (ACEI), angiotensin II-receptor blocker (ARB), beta-blocker, or calcium channel blocker may be prudent. Two current studies, the DREAM trial and the ONTARGET trial, may shed more light as to whether ACEIs or ARBs have a preferred niche in initial treatment of the hypertensive patient who is at risk for diabetes.

Joint association of coffee consumption and other factors to the risk of type 2 diabetes: a prospective study in Finland

OBJECTIVE

To examine joint associations of coffee consumption and other factors (including physical activity, obesity and alcohol consumption) with the risk of type 2 diabetes.

DESIGN

Prospective follow-up study.

SUBJECTS

In all, 10 188 Finnish men and 11 197 women aged 35-74 years without a history of stroke, coronary heart disease or diabetes at baseline.

MEASUREMENT

A self-administered questionnaire data on coffee, tea, alcohol and other food consumption, physical activity, smoking, socio-economic factors and medical history, together with measured height, weight and blood pressure using standardized protocol.

RESULTS

During a mean follow-up of 13.4 years, there were 964 incident cases of type 2 diabetes. Multivariate-adjusted (age, study year, systolic blood pressure, education, smoking, physical activity, body mass index (BMI) and fruit, vegetable, sausage, bread, alcohol and tea consumption) hazard ratio of type 2 diabetes in participants who drank 0-2, 3-6 and > or =7 cups of coffee were 1.00, 0.77 and 0.66 (P=0.022 for trend) in men, 1.00, 0.71 and 0.52 (P=0.001 for trend) in women, and 1.00, 0.75 and 0.61 (P<0.001 for trend) in men and women combined (adjusted also for sex), respectively. This inverse association was consistent in subjects with any joint levels of physical activity and BMI, and in alcohol drinkers and non-drinkers. Among obese and inactive people, coffee drinking of seven cups or more daily reduced the risk of type 2 diabetes to half.

CONCLUSIONS

Coffee drinking was associated with a reduced risk of type 2 diabetes in both men and women, and this association was observed regardless of the levels of physical activity, BMI and alcohol consumption.

Magnesium Intake and Incidence of Metabolic Syndrome Among Young Adults

Background— Studies suggest that magnesium intake may be inversely related to risk of hypertension and type 2 diabetes mellitus and that higher intake of magnesium may decrease blood triglycerides and increase high-density lipoprotein (HDL) cholesterol levels. However, the longitudinal association of magnesium intake and incidence of metabolic syndrome has not been investigated.

Methods and Results— We prospectively examined the relations between magnesium intake and incident metabolic syndrome and its components among 4637 Americans, aged 18 to 30 years, who were free from metabolic syndrome and diabetes at baseline. Metabolic syndrome was diagnosed according to the National Cholesterol Education Program/Adult Treatment Panel III definition. Diet was assessed by an interviewer-administered quantitative food frequency questionnaire, and magnesium intake was derived from the nutrient database developed by the Minnesota Nutrition Coordinating Center. During the 15 years of follow-up, 608 incident cases of the metabolic syndrome were identified. Magnesium intake was inversely associated with incidence of metabolic syndrome after adjustment for major lifestyle and dietary variables and baseline status of each component of the metabolic syndrome. Compared with those in the lowest quartile of magnesium intake, multivariable-adjusted hazard ratio of metabolic syndrome for participants in the highest quartile was 0.69 (95% confidence interval [CI], 0.52 to 0.91; P for trend <0.01). The inverse associations were not materially modified by gender and race. Magnesium intake was also inversely related to individual component of the metabolic syndrome and fasting insulin levels.

Conclusions— Our findings suggest that young adults with higher magnesium intake have lower risk of development of metabolic syndrome.

Coffee and type 2 diabetes: from beans to beta-cells

Coffee consumption has been associated with improved glucose tolerance and a lower risk of type 2 diabetes in diverse populations in the U.S., Europe, and Japan. This review discusses the strength of the evidence, relevant mechanisms, possible implications, and directions for further research. The finding that higher consumption of decaffeinated coffee was associated with a lower risk of type 2 diabetes suggests that coffee constituents other than caffeine play a role. Coffee is a source of several compounds that improved glucose metabolism in animal studies, including the chlorogenic acids and lignans. Further research on phytochemicals in coffee may lead to the identification of novel mechanisms for effects of diet on the development of type 2 diabetes. In addition, knowledge on effects of coffee components may aid in the development or selection of types of coffee with improved health effects. Longer-term randomized intervention studies that test the effects of coffee consumption on glucose tolerance are warranted. Physical activity and weight management should be the mainstay of public health strategies to prevent type 2 diabetes. For individual choices regarding coffee consumption, potential effects of coffee on various health outcomes should be considered.

PKC-mediated modulation of L-type calcium channels may contribute to fat-induced insulin resistance

Increased intracellular free calcium [Ca2+]i has been noted in adipocytes, platelets, and leukocytes of subjects with insulin resistance syndrome or allied disorders. In rodent studies, measures which increase [Ca2+]i in adipocytes and skeletal muscle are associated with impaired insulin signaling, attributable at least in part to diminished ability of insulin to activate phosphoserine phosphatase-1 (PP-1). In fat-fed insulin resistant rats, pre-treatment with a drug that selectively chelates intracellular calcium eliminates about half of the decrement in insulin-stimulated glucose uptake induced by fat feeding; since this chelator does not influence the insulin sensitivity of chow-fed rats, it is reasonable to suspect that fat feeding boosts [Ca2+]i in skeletal muscle, and that this effect is partially responsible for the associated reduction in insulin sensitivity. Clinical insulin resistance is associated with increased levels of triglycerides and other fatty acid metabolites in muscle fibers; this can give rise to diacylglycerol-mediated activation of PKC, which in turn compromises insulin signaling by triggering kinase cascades that phosphorylate IRS-1 on key serine residues. Yet there is also evidence that, in skeletal muscle, PKC activity up-regulates the function of L-type calcium channels, increasing their maximal conductance while left-shifting their voltage dependence. Thus, the PKC activation associated with fat overexposure might be expected to boost basal [Ca2+]i in skeletal muscle, potentially impeding insulin-mediated activation of PP-1. This hypothesis is consistent with several clinical studies demonstrating that long-acting inhibitors of L-type calcium channels can improve insulin sensitivity in overweight hypertensives; it should be readily testable in rodent models of fat-induced insulin resistance. Since parathyroid hormone can act on adipocytes and muscle to boost [Ca2+]i, mild secondary hyperparathyroidism associated with low calcium intakes and poor vitamin D status may contribute to insulin resistance, consistent with certain clinical and epidemiological findings. Magnesium, often thought of as a mild calcium antagonist, appears to have favorable effects on insulin sensitivity and risk for diabetes, and recent evidence indicates that increases of intracellular magnesium within the physiological range can diminish calcium influx through phosphorylated L-type calcium channels. It will be of interest to determine whether calcium antagonism does indeed underlie the favorable influence of good magnesium status on insulin function. A report that chromium picolinate can induce the plasmalemmal Ca2+-ATPase in smooth muscle cells, raises the possibility that modulation of calcium transport might play a role in the insulin-sensitizing efficacy of bioactive chromium.

Evaluation of epidemiologic evidence on the role of nutrition in the development of diabetes and its complications

This article evaluates the body of epidemiologic evidence on the effects of nutritional factors in diabetes development published within the past 5 years (2000-2004), considering strengths and weaknesses of specific studies, as well as of various study designs in general. Furthermore, this article aims to determine whether clinical practice and public health practice guidelines should, or should not, be determined based on the totality of available scientific evidence.

The impact of nuts on diabetes and diabetes risk

Nuts have many nutritional benefits: they are high in monounsaturated and polyunsaturated fats, fiber, vitamin, minerals, and phytonutrients. Population studies indicate that individuals who regularly consume nuts have reduced risk for cardiovascular disease and diabetes. In clinical trials, nuts appear to have a neutral effect on glucose and insulin, and a beneficial effect on lipid profile. Thus, nuts can be a healthy dietary component for individuals with diabetes or those at risk for diabetes, providing overall caloric intake is regulated to maintain a healthy body weight.

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.

Mineral and vitamin deficiencies can accelerate the mitochondrial decay of aging

Mitochondrial oxidative decay, which is a major contributor to aging, is accelerated by many common micronutrient deficiencies. One major mechanism is inhibition of the pathway of heme biosynthesis in mitochondria, which causes a deficit of heme-a. Heme-a, only found in Complex IV, is selectively diminished, resulting in oxidant leakage and accelerated mitochondrial decay, which leads to DNA damage, neural decay, and aging. We emphasize those deficiencies, which appear to cause damage through this mechanism, particularly minerals such as iron (25% of menstruating women ingest <50% of the RDA) or zinc (10% of the population ingest <50% of the RDA). Several vitamin deficiencies, such as biotin or pantothenic acid, also increase mitochondrial oxidants through this mechanism. Additionally, other minerals such as magnesium and manganese that play a role in mitochondrial metabolism, but do not affect heme directly, are discussed. An optimum intake of micronutrients could tune up metabolism and give a marked increase in health, particularly for the poor, elderly, and obese, at little cost.

Can type 2 diabetes mellitus be considered preventable?

The primary prevention of type 2 diabetes mellitus (T2DM) is of great importance. There is now substantial evidence that T2DM can be prevented or delayed by lifestyle modification. A statistically significant reduction of relative risk of newly diagnosed T2DM was observed in large clinical trials with metformin, acarbose or orlistat in subjects with impaired glucose tolerance as well as with troglitazone in women with previous gestational diabetes. A relative risk reduction of newly diagnosed diabetes was observed in prospective, double blind clinical studies evaluating the effect of different antihypertensive drugs (ACE-inhibitors, angiotensin repector blockers, calcium channel blockers) or that of lipid-lowering agents (pravastatin) on the cardiovascular morbidity and mortality in high risk patients. In studies with postmenopausal hormone replacement therapy a relative risk reduction of newly developed T2DM was also observed. Thus, T2DM should be considered as a preventable disease. Nevertheless, it is noteworthy that oral antidiabetic drugs with an indication of preventing T2DM are not registered in several countries at present, so that drug therapy should not be used as a routine for preventing diabetes. On the other hand, patients with pre-diabetes (impaired fasting glycaemia, impaired glucose tolerance) should be given counseling on weight loss as well as instruction for increasing physical activity in order to prevent T2DM.

A dietary pattern protective against type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition (EPIC)--Potsdam Study cohort

AIMS/HYPOTHESIS

The aim of this study was to identify a dietary pattern associated with diabetes-related biomarkers and to investigate whether this pattern is associated with the incidence of type 2 diabetes.

METHODS

A nested case-control study of 192 cases of incident type 2 diabetes and 382 control subjects matched for sex and age was conducted. All subjects were participants in the population-based European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Study. Dietary pattern score was derived using intake data on 48 food groups as exposure variables and the biomarkers HbA1c, HDL cholesterol, C-reactive protein and adiponectin as response variables in reduced rank regression. The association of the score with diabetes risk was estimated by conditional logistic regression analysis.

RESULTS

A high score for the identified dietary pattern was characterised by a high intake of fresh fruit and a low intake of high-caloric soft drinks, beer, red meat, poultry, processed meat, legumes and bread (excluding wholegrain bread). Subjects with high scores had high plasma concentrations of HDL cholesterol and adiponectin and low plasma concentrations of HbA1c and C-reactive protein. After multivariate adjustment, the odds ratios for type 2 diabetes across increasing quintiles of the dietary pattern score were 1.0, 0.59, 0.51, 0.26 and 0.27, respectively (p = 0.0006 for trend).

CONCLUSIONS/INTERPRETATION

A high score for the identified dietary pattern is associated with a more favourable biomarker profile and a substantially reduced incidence of type 2 diabetes.

Primary prevention of diabetes: what can be done and how much can be prevented?

Although it is widely believed that type 2 diabetes mellitus is the result of a complex interplay between genetic and environmental factors, compelling evidence from epidemiologic studies indicates that the current worldwide diabetes epidemic is largely due to changes in diet and lifestyle. Prospective cohort studies and randomized clinical trials have demonstrated that type 2 diabetes can be prevented largely through moderate diet and lifestyle modifications. Excess adiposity is the most important risk factor for diabetes, and thus, maintaining a healthy body weight and avoiding weight gain during adulthood is the cornerstone of diabetes prevention. Increasing physical activity and reducing sedentary behaviors such as prolonged TV watching are important both for maintaining body weight and improving insulin sensitivity. There is increasing evidence that the quality of fat and carbohydrate plays a more important role than does the quantity, and thus, public health strategies should emphasize replacing saturated and trans fats with unsaturated fats and replacing refined grain products with whole grains. Recent studies have also suggested a potential role for coffee, dairy, nuts, magnesium, and calcium in preventing diabetes. Overall, a healthy diet, together with regular physical activity, maintenance of a healthy weight, moderate alcohol consumption, and avoidance of sedentary behaviors and smoking, could nearly eliminate type 2 diabetes. However, there is still a wide gap between what we know and what we practice in the field of public health; how to narrow that gap remains a major public health challenge.

Metabolic syndrome and other factors associated with increased risk of diabetes

The prevalence of diabetes has increased dramatically in the last 3 decades. Metabolic syndrome is a strong risk factor for incident diabetes. Among components of metabolic syndrome, obesity and abnormal carbohydrate metabolism are the most significant predictors. Primary care physicians should identify patients at risk and monitor their fasting glucose and/or postprandial glucose to enable timely diagnosis of diabetes and appropriate interventions. Lifestyle interventions that help reduce body weight and pharmacologic interventions that address insulin resistance and/or postprandial glycemia may help prevent diabetes. Intensive cardiovascular risk factor management should be an integral component of any diabetes prevention plan.

Magnesium deficiency is associated with insulin resistance in obese children

OBJECTIVE

Magnesium deficiency has been associated with insulin resistance (IR) and increased risk for type 2 diabetes in adults. This study was designed to determine whether obese children exhibit serum or dietary magnesium deficiency and its potential association with IR.

RESEARCH DESIGN AND METHODS

We studied 24 obese nondiabetic children (BMI > or =85th percentile) and 24 sex- and puberty-matched lean control subjects (BMI <85th percentile). We measured serum magnesium, indexes of insulin sensitivity, dietary magnesium intake (using a food frequency questionnaire), and body composition (by air displacement plethysmography).

RESULTS

Serum magnesium was significantly lower in obese children (0.748 +/- 0.015 mmol/l, means +/- SE) compared with lean children (0.801 +/- 0.012 mmol/l) (P = 0.009). Serum magnesium was inversely correlated with fasting insulin (r(s) = -0.36 [95% CI -0.59 to -0.08]; P = 0.011) and positively correlated with quantitative insulin sensitivity check index (QUICKI) (0.35 [0.06-0.58]; P = 0.015). Dietary magnesium intake was significantly lower in obese children (obese: 0.12 +/- 0.004 vs. lean: 0.14 +/- 0.004 mg/kcal; P = 0.003). Dietary magnesium intake was inversely associated with fasting insulin (-0.43 [-0.64 to -0.16]; P = 0.002) and directly correlated with QUICKI (0.43 [0.16-0.64]; P = 0.002).

CONCLUSIONS

The association between magnesium deficiency and IR is present during childhood. Serum magnesium deficiency in obese children may be secondary to decreased dietary magnesium intake. Magnesium supplementation or increased intake of magnesium-rich foods may be an important tool in the prevention of type 2 diabetes in obese children.