Calcium and phosphate concentrations and future development of type 2 diabetes: the Insulin Resistance Atherosclerosis Study

U-shaped association between serum calcium and in-hospital mortality in diabetes patients with congestive heart failure: a cohort study

Previous studies have reported that the significant association between serum calcium and mortality substantially in patients, especially among those with intensive care unit (ICU). And In diabetes mellitus, congestive heart failure (CHF) is a significant comorbidity. We aim to evaluate the association between serum calcium levels and in-hospital mortality among patients with diabetes and congestive heart failure. The participants in this study were extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. To scrutinize potential associations between serum calcium levels and in-hospital mortality, a comprehensive analysis encompassing multivariate logistic regression, cubic spline function model, threshold effect analysis, and subgroup analysis was performed. This retrospective cohort study encompassed 7063 patients, among whom the in-hospital mortality stood at 12.2%. In the multivariate logistic regression, adjusted odds ratios (ORs) were contrasted with the reference category Q6 (8.8-9.1 mg/dL) for serum calcium levels and in-hospital mortality. The adjusted ORs for Q1 (≤ 7.7 mg/dL), Q2 (7.7-8 mg/dL), and Q7 (≥ 9.1 mg/dL) were 1.69 (95% CI 1.17-2.44, p = 0.005), 1.62 (95% CI 1.11-2.36, p = 0.013), and 1.57 (95% CI 1.1-2.24, p = 0.012) respectively. The dose-response analysis uncovered a U-shaped relationship between serum calcium levels and in-hospital mortality in diabetic patients with heart failure. Subgroup analyses confirmed result stability notwithstanding the influence of diverse factors. Our investigation revealed a U-shaped correlation between serum calcium levels and in-hospital mortality in diabetes patients with congestive heart failure, pinpointing a significant inflection point at 9.05 mg/dL.

Microelement strontium and human health: comprehensive analysis of the role in inflammation and non-communicable diseases (NCDs)

Strontium (Sr), a trace element with a long history and a significant presence in the Earth's crust, plays a critical yet often overlooked role in various biological processes affecting human health. This comprehensive review explores the multifaceted implications of Sr, especially in the context of non-communicable diseases (NCDs) such as cardiovascular diseases, osteoporosis, hypertension, and diabetes mellitus. Sr is predominantly acquired through diet and water and has shown promise as a clinical marker for calcium absorption studies. It contributes to the mitigation of several NCDs by inhibiting oxidative stress, showcasing antioxidant properties, and suppressing inflammatory cytokines. The review delves deep into the mechanisms through which Sr interacts with human physiology, emphasizing its uptake, metabolism, and potential to prevent chronic conditions. Despite its apparent benefits in managing bone fractures, hypertension, and diabetes, current research on Sr's role in human health is not exhaustive. The review underscores the need for more comprehensive studies to solidify Sr's beneficial associations and address the gaps in understanding Sr intake and its optimal levels for human health.

Exploration of the Shared Hub Genes and Biological Mechanism in Osteoporosis and Type 2 Diabetes Mellitus based on Machine Learning

A substantial amount of evidence suggests a close relationship between osteoporosis (OP) and Type 2 Diabetes Mellitus (T2DM), but the mechanisms involved remain unknown. Therefore, we conducted this study with the aim of screening for hub genes common to both diseases and conducting a preliminary exploration of common regulatory mechanisms. In the present study, we first screened genes significantly associated with OP and T2DM by the univariate logistic regression algorithm. And then, based on cross-analysis and random forest algorithm, we obtained three hub genes (ACAA2, GATAD2A, and VPS35) and validated the critical roles and predictive performance of the three genes in both diseases by differential expression analysis, receiver operating characteristic (ROC) curves, and genome wide association study (GWAS) analysis. Finally, based on gene set enrichment analysis (GSEA) and the construction of the miRNA-mRNA regulatory network, we conducted a preliminary exploration of the co-regulatory mechanisms of three hub genes in two diseases. In conclusion, this study provides promising biomarkers for predicting and treating both diseases and offers novel directions for exploring the common regulatory mechanisms of both diseases.

Association Between Primary Hyperparathyroidism and Secondary Diabetes Mellitus: Findings From a Scoping Review

An ill-defined association exists between diabetes mellitus (insulin resistance) and primary hyperparathyroidism. This article explores this phenomenon while providing an explanation for such a relationship and reviewing the evidence regarding the response to insulin sensitivity following a parathyroidectomy. Primary hyperparathyroidism may increase the risk of developing insulin resistance; peculiarly, this is not present in all patients. It is likely that both intracellular hypercalcemia and hypophosphatemia alter the insulin receptor expression and response; the contribution of parathyroid hormone is less clear. Following parathyroidectomy, patients may demonstrate improvement in their insulin sensitivity, while others have no response or a detrimental effect. A varied phenotype exists among patients, and furthermore, it is unclear why certain patients demonstrate improvement in insulin sensitivity following a parathyroidectomy, whereas others fail to do so. While this review provides a broad overview of the general endocrine community, it is imperative to note that clinical applicability is limited until further studies address these remaining uncertainties. Due to the lack of understanding regarding this endocrinological enigma, the presence of insulin resistance, at this present time, should not be a criterion for a parathyroidectomy.

Sexual dimorphisms in serum calcium and phosphate concentrations in the Rotterdam Study

Sex differences in serum phosphate and calcium have been reported but the exact nature and underlying regulatory mechanisms remain unclear. We aimed to compare calcium and phosphate concentrations between sexes, and explore potential covariates to elucidate underlying mechanisms of sex differences in a prospective, population-based cohort study. Pooled data of subjects > 45 years from three independent cohorts of the Rotterdam Study (RS) were used: RS-I-3 (n = 3623), RS-II-1 (n = 2394), RS-III-1 (n = 3241), with separate analyses from an additional time point of the first cohort RS-I-1 (n = 2688). Compared to men, women had significantly higher total serum calcium and phosphate concentrations which was not explained by BMI, kidney function nor smoking. Adjustment for serum estradiol diminished sex differences in serum calcium while adjustment for serum testosterone diminished sex differences in serum phosphate. Adjustment for vitamin D and alkaline phosphatase did not change the association between sex and calcium or phosphate in RS-I-1. In the sex-combined group, both serum calcium and phosphate decreased with age with a significant interaction for sex differences for serum calcium but not phosphate. In sex-stratified analyses, serum estradiol but not testosterone was inversely associated with serum calcium in both sexes. Serum estradiol was inversely associated with serum phosphate in both sexes to a similar degree, while serum testosterone was inversely associated with serum phosphate in both sexes with an apparent stronger effect in men than in women. Premenopausal women had lower serum phosphate compared to postmenopausal women. Serum testosterone was inversely associated with serum phosphate in postmenopausal women only. In conclusion, women > 45 years have higher serum calcium and phosphate concentrations compared to men of similar age, not explained by vitamin D or alkaline phosphatase concentrations. Serum estradiol but not testosterone was inversely associated with serum calcium while serum testosterone was inversely associated with serum phosphate in both sexes. Serum testosterone may in part explain sex differences in serum phosphate while estradiol could partly explain sex differences in serum calcium.

Interaction between inorganic phosphate concentration and glucose metabolism in mild refeeding syndrome model

Refeeding syndrome is a major clinical problem that leads to fatal complications in patients suffering from malnutrition. Hypophosphatemia inevitably is observed at the onset of refeeding syndrome and therefore is monitored during refeeding; however, the causes of metabolic changes in phosphate concentration during refeeding remain poorly understood. In a previous study, we established a refeeding syndrome model employing total parenteral nutrition with insulin-induced hypophosphatemia, but the symptoms were severe and the metabolic mechanisms in this model may not have been representative of clinical conditions. Therefore, we established a new animal model of mild refeeding syndrome by using a shorter fasting period followed by a single refeeding. These mild refeeding syndrome-model rats exhibited hypophosphatemia without increases in urinary phosphate excretion. Interestingly, administration of the combination of phosphate and insulin during refeeding promoted insulin secretion during refeeding. This model implies that Pi may directly promote insulin secretion in pancreatic cells. These results clarify the interaction between phosphate and glucose metabolism pancreatic cells during refeeding syndrome in a mild refeeding syndrome model.

The Association between Admission Serum Phosphorus and Preoperative Deep Venous Thrombosis in Geriatric Hip Fracture: A Retrospective Study

OBJECTIVE

This study aimed to evaluate the association between serum phosphorus level and preoperative deep vein thrombosis (DVT) in geriatric hip fractures.

METHODS

Older adults with hip fractures were screened between January 2015 and September 2019. Demographic and clinical characteristics of the patients were collected. Multivariate binary logistic regression and generalized additive models were used to identify the linear and nonlinear associations between serum phosphorus levels and preoperative DVT. Analyses were performed using Empower Stats and R software.

RESULTS

In this study, 1818 patients were included, with an average age of 79.39 ± 6.87. Of these, 30.25% were males, and 580 patients had DVT. The study found that when serum phosphorus was used as a continuous variable, there was a statistically significant difference in the relationship between blood phosphorus and the occurrence of DVT (p < 0.05). Furthermore, we also found curvilinear relationships. Serum phosphorus = 0.71 mmol/L was the inflection point in the curve. When serum phosphorus was <0.71 mmol/L, the serum phosphorus was associated with DVT (OR = 1.64; 95% CI: 1.04-2.59; p = 0.0333). With a 0.1 mmol/L increase, the DVT increased 0.64 times. When phosphorus was >0.71 mmol/L, there was no significant difference in the correlation between serum phosphorus levels and DVT (OR = 1.03; 95% CI: 0.98-1.09; p = 0.186).

CONCLUSION

Serum phosphorus was nonlinearly associated with preoperative DVT in geriatric patients with hip fractures, and serum phosphorus level could be considered a predictor of DVT risk.

A Review of Current Evidence on the Relationship between Phosphate Metabolism and Metabolic Syndrome

Phosphorus, present as phosphate in biological systems, is an essential mineral for various biological activities and biochemical processes. Numerous studies have indicated that disturbed phosphate balance may contribute to the development of metabolic syndrome (MetS). However, no consistent result was found on the association between phosphorus intake and serum phosphate concentration with MetS. It is believed that both positive and negative impacts of phosphorus/phosphate co-exist in parallel during MetS condition. Reduced phosphate level contributed to the development of obesity and hyperglycaemia. Low phosphate is believed to compromise energy production, reduce exercise capacity, increase food ingestion, and impair glucose metabolism. On the other hand, the effects of phosphorus/phosphate on hypertension are rather complex depending on the source of phosphorus and subjects' health conditions. Phosphorus excess activates sympathetic nervous system, renin-angiotensin-aldosterone system, and induces hormonal changes under pathological conditions, contributing to the blood pressure-rising effects. For lipid metabolism, adequate phosphate content ensures a balanced lipid profile through regulation of fatty acid biosynthesis, oxidation, and bile acid excretion. In conclusion, phosphate metabolism serves as a potential key feature for the development and progression of MetS. Dietary phosphorus and serum phosphate level should be under close monitoring for the management of MetS.

Phosphate Dysregulation and Metabolic Syndrome

Phosphorus is one of the most abundant minerals in the human body. It is essential for almost all biochemical activities through ATP formation, intracellular signal transduction, cell membrane formation, bone mineralization, DNA and RNA synthesis, and inflammation modulation through various inflammatory cytokines. Phosphorus levels must be optimally regulated, as any deviations may lead to substantial derangements in glucose homeostasis. Clinical studies have reported that hyperphosphatemia can increase an individual's risk of developing metabolic syndrome. High phosphate burden has been shown to impair glucose metabolism by impairing pancreatic insulin secretion and increasing the risk of cardiometabolic disorders. Phosphate toxicity deserves more attention as metabolic syndrome is being seen more frequently worldwide and should be investigated further to determine the underlying mechanism of how phosphate burden may increase the cardiometabolic risk in the general population.

Association between vitamin D serum levels and insulin resistance assessed by HOMA-IR among non-diabetic adults in the United States: Results from NHANES 2007-2014

Insulin resistance, a pathological response to insulin hormone in insulin-dependent cells, is characterized by the presence of high glucose and insulin concentrations. The homeostasis model of insulin resistance (HOMA-IR) is one of the most used indexes to estimate insulin resistance by assessing the fasting glucose and insulin levels. An association was observed between vitamin D levels and insulin resistance, which varied in different ethnic groups, and there is some evidence that vitamin D supplementation could contribute to the improvement of insulin resistance. This study assessed the association between 25-hydroxyvitamin D (25[OH]D) concentration and HOMA-IR in American adults aged 20 years and older, without diabetes and other chronic diseases that can influence insulin resistance. The data from the National Health and Nutrition Examination Survey (NHANES) 2007–2014 were used by exploiting the free and publicly-accessible web datasets. Linear regression models were performed to evaluate the association between serum 25(OH)D concentration and HOMA-IR, and a negative association was observed, which remained significant following the adjustment for age, gender, race/ethnicity, education, body mass index (BMI), physical activity, the season of examination, current smoking, hypertension, the use of drugs which can influence insulin resistance, serum bicarbonates, triglycerides, and calcium and phosphorus levels. Only in non-Hispanic Blacks was this inverse association between vitamin D and HOMA-IR not observed in the fully adjusted model. Further studies are needed to explain the mechanisms of the observed ethnic/racial differences in the association of vitamin D levels with HOMA-IR.

Plasma Calcium and Phosphorus Levels and Cardiovascular Disease Risks in Egyptian Type 2 Diabetic Patients

Background: Cardiovascular complication of diabetes is considered an important issue that needs deep investigations. The levels of plasma calcium (Ca) and phosphorus (P) have been implicated as having an association to cardiovascular diseases. AIM: The objective of the present research was to study the plasma levels of both Ca and P and their association to the atherogenic ratio; total cholesterol: high density lipoprotein-cholesterol and the plasma albumin in male and female patients with type 2-diabetes. The interrelation between anthropometric parameters represented by body mass index (BMI), waist circumference and waist/hip ratio with Ca and P were studied. Also, the association between plasma Ca and P with their dietary intake were investigated. Subjects and METODS: Thirty-one type 2-diabetic male and female patients participated in the study, in addition of ten healthy subjects. Biochemical parameters, anthropometric measurements and nutrients′ intake were assessed. Biochemical parameters include plasma Ca, P, lipid profile, albumin, liver function tests and creatinine. RESULTS: Plasma Ca levels of female patients of BMI> 30 kg/m2 demonstrated significant increase compared to the control group.  All male and female patients showed significant increase in plasma P compared to the control group. Glycosylated hemoglobin of male and females showed significant high values compared to the control group except for diabetic male of BMI>30 kg/m2 that showed insignificant increase. No significant changes in plasma TG and LDL-C levels were noticed compared to the control.  Plasma TC of patients showed significant high levels compared to the control group. The levels of HDL-C of patients were significantly lower than that of the control. The ratios of TC/HDL-C diabetic patients either male or female and whatever their BMI were significantly higher than that of the control. No significant changes in plasma activities of ALT and AST and bilirubin levels were observed among the different groups including the control.  Plasma albumin levels demonstrated significant reduction compared to the control group whatever their sexes or BMI. Plasma creatinine levels of the different diabetic groups showed insignificant change from the control group except for the male group of BMI<30 kg/m2 that showed significant elevation. In male, plasma Ca showed significant negative correlation with albumin and positive correlation with creatinine and dietary vitamin D. In female, a significant positive correlation was noticed between plasma and dietary P while a negative correlation was observed between plasma Ca and dietary iron. CONCLUSION: Elevated of plasma P together with reduced plasma albumin and elevated TC/HDL-C may reflect an association of plasma P to CVD in male and female diabetic subjects while high plasma Ca might predict CVD in only female diabetic patients of BMI > 30 kg/m2.

Sex-Specific Associations Between Serum Phosphate Concentration and Cardiometabolic Disease: A Cohort Study on the Community-Based Older Chinese Population

PURPOSE

This study aimed to investigate the association between sex-specific baseline serum phosphate and the incidence of new-onset cardiometabolic disease in a cohort of Shanghai-based older Chinese individuals.

PATIENTS AND METHODS

A community cohort of 5000 disease-free Chinese men and women was recruited in 2013 and followed until 2017 for the development of cardiometabolic disease. Participants underwent index and follow-up health screens at the Tongji Medical School affiliated Shanghai East Hospital, including blood biochemistry analysis, anthropometric measurements, interview on health-related behaviors, and clinical evaluation.

RESULTS

Higher baseline serum phosphate (>1.25 mmol/L) was significantly associated with new-onset type-2 diabetes mellitus (HR 1.730, 95% CI 1.127-2.655) and metabolic syndrome (HR 0.640, 95% CI 1.085-2.155) in women. Baseline serum phosphate was associated with age, BMI, waist circumference, SBP, total calcium, bicarbonate, and total cholesterol in women. The estimated risk of developing diabetes mellitus in women with inorganic phosphate >1.25 mmol/L was 14.54%. Inorganic phosphate accounted for 9.2% of the variance explained in a total estimated 14.52% of variance attributed to BMI, total cholesterol, total calcium, waist circumference, and inorganic phosphate.

CONCLUSION

Serum phosphate concentration showed sex-specific associations with diabetes and metabolic syndrome. Higher inorganic phosphate was associated with increased risk of developing diabetes mellitus in women. These findings may be important in the assessment of individualized metabolic risk.

Perspectives on the systematic review for the 2020 Dietary Reference Intakes for Koreans for calcium

An accurate assessment of the recommended calcium (Ca) intake may contribute to reducing the risk of fractures and chronic diseases, ultimately improving quality of life. This review was performed to summarize key findings of Ca studies, investigate the effect of Ca intake on health outcomes, and determine the adequacy of evidence to revise the 2015 Dietary Reference Intakes for Koreans (KDRIs) for Ca in 2020. Databases were searched for intervention studies that assessed health outcomes by providing Ca in diets or as supplements. The framework of the systematic review comprised conducting literature searches, data extraction, quality assessment of the literature, and summarizing key findings relevant to set the Estimated Average Requirement (EAR) and Tolerable Upper Intake Level (UL) for Ca for the 2020 KDRI. The final search was performed in June 2019. A total of 13,309 studies were identified through databases and manual search. Sixtyfive studies were included in the final quality assessment and were summarized according to health indicators. As bone health was used as an indicator of the EAR for Ca, literature reports on bone health were further categorized by the life-cycle stage of the participants. This systematic review did not find new evidence that could be applied to the general Korean adult population, including postmenopausal women, for defining a new EAR for Ca in the 2020 KDRIs. Evidence in most of the reviewed literature was considered weak; however, some evidence was found that could improve the criteria on how the EAR for Ca was determined in children and adolescents. A review of the literature for the 2020 KDRIs for Ca did not find strong evidence in order to change the recommended values of the 2015 KDRIs. More clinical interventions are required among Koreans to strengthen the body of evidence to warrant the revision of the KDRIs.

Neutrophils and their role in the aetiopathogenesis of type 1 and type 2 diabetes

Multiple and complex aetiological processes underlie diabetes mellitus, which invariably result in the development of hyperglycaemia. Although there are two prevalent distinct forms of the disease, that is, type 1 and type 2 diabetes, accumulating evidence indicates that these syndromes share more aetiopathological mechanisms than originally thought. This compels a rethinking of the approaches to prevent and treat the different manifestations of what eventually becomes a hyperglycaemic state. This review aims to address the involvement of neutrophils, the most abundant type of granulocytes involved in the initiation of the acute phase of inflammation, in the aetiopathogenesis of diabetes mellitus, with a focus on type 1 and type 2 diabetes. We review the evidence that neutrophils are the first leucocytes to react to and accumulate inside target tissues of diabetes, such as the pancreas and insulin-sensitive tissues. We then review available data on the role of neutrophils and their functional alteration, with a focus on NETosis, in the progression towards clinical disease. Finally, we review potential approaches as secondary and adjunctive treatments to limit neutrophil-mediated damage in the prevention of the progression of subclinical disease to clinical hyperglycaemia.

The Association between Branched-Chain Amino Acids (BCAAs) and Cardiometabolic Risk Factors in Middle-Aged Caucasian Women Stratified According to Glycemic Status

We examined the glycemic status-stratified relationships between total serum branched-chain amino acid (BCAA) concentrations and cardiometabolic risk factors in middle-aged Caucasian women. The study included 349 women divided into 2 subgroups: a normoglycemic group (NG, n = 184) and a dysglycemic group (DG, n = 165). Blood samples, anthropometric parameters, and blood pressure were measured. HOMA-IR, albumin-corrected calcium (CCa), and fatty liver index (FLI) were calculated. BCAA concentrations were higher in the women with dysglycemia. BCAAs moderately correlated with BMI and FLI in the NG group and with BMI, FLI, total calcium (TCa), CCa, HbA1c, TG/HDL-C, and HDL-C in the DG group. After adjusting for age and BMI, correlations for TCa, CCa, HbA1c, HDL-C, and TG/HDL-C remained significant. The coexistence of increased BCAAs with dysglycemic status was associated with markedly higher concentrations of TCa, CCa, HbA1c, and TG, which were not observed in the DG women with low level of BCAAs. Multiple regression showed that TCa or CCa, age and BCAAs were significantly associated with HbA1c independently of BMI only in the DG group. We conclude that dysglycemia in particular predisposes women to a significant relationship between total BCAAs and circulating calcium and HbA1c, and that these relationships are independent of BMI and may reflect the pathophysiological calcium-dependent mechanisms connecting BCAAs with metabolic disturbances.

Extracellular Inorganic Phosphate-Induced Release of Reactive Oxygen Species: Roles in Physiological Processes and Disease Development

Inorganic phosphate (Pi) is an essential nutrient for living organisms and is maintained in equilibrium in the range of 0.8-1.4 mM Pi. Pi is a source of organic constituents for DNA, RNA, and phospholipids and is essential for ATP formation mainly through energy metabolism or cellular signalling modulators. In mitochondria isolated from the brain, liver, and heart, Pi has been shown to induce mitochondrial reactive oxygen species (ROS) release. Therefore, the purpose of this review article was to gather relevant experimental records of the production of Pi-induced reactive species, mainly ROS, to examine their essential roles in physiological processes, such as the development of bone and cartilage and the development of diseases, such as cardiovascular disease, diabetes, muscle atrophy, and male reproductive system impairment. Interestingly, in the presence of different antioxidants or inhibitors of cytoplasmic and mitochondrial Pi transporters, Pi-induced ROS production can be reversed and may be a possible pharmacological target.

Pathophysiological Implications of Imbalances in Fibroblast Growth Factor 23 in the Development of Diabetes

Observational studies have associated the increase in fibroblast growth factor (FGF) 23 levels, the main regulator of phosphate levels, with the onset of diabetes. These studies open the debate on the plausible existence of undescribed diabetogenic mechanisms derived from chronic supraphysiological levels of FGF23, a prevalent condition in chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. These maladaptive and diabetogenic responses to FGF23 may occur at different levels, including a direct effect on the pancreatic ß cells, and an indirect effect derived from the stimulation of the synthesis of pro-inflammatory factors. Both mechanisms could be mediated by the binding of FGF23 to noncanonical receptor complexes with the subsequent overactivation of signaling pathways that leads to harmful effects. The canonical binding of FGF23 to the receptor complex formed by the receptor FGFR1c and the coreceptor αKlotho activates Ras/MAPK/ERK signaling. However, supraphysiological concentrations of FGF23 favor non-αKlotho-dependent binding of this molecule to other FGFRs, which could generate an undesired overactivation of the PLCγ/CN/NFAT pathway, as observed in cardiomyocytes and hepatocytes. Moreover, the decrease in αKlotho expression may constitute a contributing factor to the appearance of these effects by promoting the nonspecific activation of the PLCγ/CN/NFAT to the detriment of the αKlotho-dependent Ras/MAPK/ERK pathway. The description of these mechanisms would allow the development of new therapeutic targets susceptible to be modified by dietary changes or by pharmacological intervention.

The Relationship Between Menopause and Metabolic Syndrome: Experimental and Bioinformatics Analysis

Menopausal hormonal changes have been associated with the emergence of the metabolic syndrome (MetS) and its consequences such as type 2 diabetes (T2D) and cardiovascular diseases (CVD). The common gene signature and the associated signaling pathways of MetS, T2D, CVD and menopause status have not been widely studied. We analyzed a total of 314 women aged between 35 and 75 years. The sample was divided into two groups: Group I, including women in the premenopausal period and Group II, comprising women in the post-menopausal period. The presence of MetS and its components were evaluated, as well as occurrence of T2D and CVD in both groups. We also exploited the translational bioinformatics approach to choose the common gene signatures for MetS, T2D, CVD and the menopause status. The frequency of the MetS was significantly higher in postmenopausal women than in premenopausal ones (67.1 vs. 27.2%, p < 0.001). Gene mining analysis revealed that a total of 47 genes were commonly associated with MetS, T2D, CVD and the menopausal changes. The gene enrichment analysis showed that these genes were markedly enriched in biological processes, including positive regulation of binding, positive regulation of leukocyte cell-cell adhesion, regulation of lipid localization. Furthermore, P53 signaling pathway, prolactin signaling pathway, parathyroid hormone synthesis, secretion and action were the top enriched pathways. Additionally, network analysis revealed TGFB1, SPP1, MMP2, MMP9, CCL2, IGF1, EGFR, ICAM1, TNF and IL6 as important hub genes with significant interacting partners. These hub genes identified in our study may play key role in menopausal changes and influence the risks of MetS, T2D and CVD.

Increased serum calcium levels are associated with carotid atherosclerotic plaque in normocalcaemic individuals with type 2 diabetes

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) have an elevated risk of atherosclerotic cardiovascular disease. Although previous data have suggested that serum calcium levels could be involved in T2DM and cardiovascular disease, whether this applies in T2DM patients with atherosclerosis remains unclear. This study therefore aimed to investigate the relationship between serum calcium levels within the physiological ranges and carotid atherosclerotic plaque in T2DM patients.

METHODS

A total of 594 normocalcaemic in-patients with T2DM were recruited, of whom 231 had carotid atherosclerotic plaque. Serum calcium levels were measured and carotid ultrasonography was performed.

RESULTS

Patients with plaque had significantly higher serum albumin-corrected calcium than those without plaque [9.02 (8.78-9.34) mg/dL versus 8.86 (8.66-9.06) mg/dL, p < 0.001]. As serum albumin-corrected calcium levels increased across tertiles, the percentage of plaque increased (27.6%, 35.5%, and 55.7%; p < 0.001). Logistic regression showed that serum albumin-corrected calcium levels were independently and positively correlated with the presence of plaque, but not parathyroid hormone levels. Compared with patients in the lowest serum calcium tertiles, the odds ratio for plaque in patients in the upper quartile was 2.47 (95% confidence interval 1.51-4.03, p < 0.001) after adjustment for potential confounders.

CONCLUSION

Serum albumin-corrected calcium levels are elevated in patients with T2DM and carotid atherosclerotic plaques.

Association of Serum Calcium and Phosphate Concentrations with Glucose Metabolism Markers: The Furukawa Nutrition and Health Study

Calcium and phosphate may play an important role in cardio-metabolic abnormalities, including type 2 diabetes; however, epidemiological evidence of the association of calcium and phosphate status with glucose metabolism among Asians is limited. In the current study, we performed a cross-sectional analysis of the association of serum calcium, phosphate, and calcium–phosphate product concentrations with glucose metabolism markers among Japanese individuals. Overall, 1701 workers (aged 18–78 years) who participated in a health survey were enrolled in this study. Multivariable linear regression models were used to estimate means of homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of β-cell function (HOMA-β), and glycated hemoglobin (HbA1c). Serum calcium concentration was positively associated with HOMA-IR and HbA1c (p for trend < 0.01). Multivariable-adjusted means (95% confidence interval (CI)) of HOMA-IR for the lowest and highest quartiles of serum calcium were 0.78 (0.75–0.82) and 1.01 (0.96–1.07), respectively. The corresponding values for HbA1c were 5.24 (5.22–5.27) and 5.29 (5.26–5.32), respectively. Serum phosphate and calcium–phosphate product concentrations were inversely associated with HOMA-IR (p for trend < 0.01). Multivariable-adjusted means (95% CI) of HOMA-IR for the lowest and highest quartiles of serum phosphate were 1.04 (0.99–1.09) and 0.72 (0.69–0.76), respectively. The corresponding values for calcium–phosphate product were 1.04 (0.99–1.09) and 0.73 (0.69–0.77), respectively. The current findings suggest that higher serum calcium and lower serum phosphate concentrations are associated with IR among apparently healthy adults.

Circulating calcium levels and the risk of type 2 diabetes: a systematic review and meta-analysis

Abnormal Ca homeostasis has been associated with impaired glucose metabolism. However, the epidemiological evidence is controversial. We aimed to assess the association between circulating Ca levels and the risk of type 2 diabetes mellitus (T2DM) or abnormal glucose homeostasis through conducting a systematic review and meta-analysis. Eligible studies were identified by searching electronic database (PubMed, Embase and Google Scholar) and related references with de novo results from primary studies up to December 2018. A random-effects meta-analysis was performed to estimate the weighted relative risks (RR) and 95 % CI for the associations. The search yielded twenty eligible publications with eight cohort studies identified for the meta-analysis, which included a total of 89 165 participants. Comparing the highest with the lowest category of albumin-adjusted serum Ca, the pooled RR was 1·14 (95 % CI 1·05, 1·24) for T2DM (n 51 489). Similarly, serum total Ca was associated with incident T2DM (RR 1·25; 95 % CI 1·10, 1·42) (n 64 502). Additionally, the adjusted RR for 1 mg/dl increments in albumin-adjusted serum Ca or serum total Ca levels was 1·16 (95 % CI 1·07, 1·27) and 1·19 (95 % CI 1·11, 1·28), respectively. The observed associations remained with the inclusion of a cohort study with ionised Ca as the exposure. However, data pooled from neither case-control (n 4) nor cross-sectional (n 8) studies manifested a significant correlation between circulating Ca and glucose homeostasis. In conclusion, accumulated data from the cohort studies suggest that higher circulating Ca levels are associated with an augmented risk of T2DM.

Relations between serum magnesium and calcium levels and body composition and metabolic parameters in women with fibromyalgia

OBJECTIVE

Correlate serum magnesium (Mg) and Calcium (Ca) levels with body composition and metabolic parameters in women with fibromyalgia (FM).

PATIENTS AND METHODS

Cross-sectional study compared with a control group paired by age and body mass index (BMI) of adult women diagnosed with fibromyalgia. All participants went through assessment of their body composition through dual-energy X-ray absorptiometry (DXA) and had blood samples collected for dosing of Mg, Ca, C-reactive Protein (CRP), lipidogram and glycemia.

RESULTS

53 women with FM (average age 48.1 ± 8.2 years, average BMI 26.6 ± 4.5 kg/m²) and 50 control women (average age 47.1 ± 9.9 years, average BMI 25.6 ± 3.6 kg/m²) participated in the study. Serum levels turned out to have inverse correlation with CRP in the FM group (r = - 0.29, p = 0.03) and with BMI and glycemia in the control group (r = 0.31; p = 0.02 and r = 0.48; p = 0.0004 respectively). Serum levels of calcium correlated with triglycerides (r = 0.29; p = 0.03) in the FM group and with glycemia in the control group (r = 0.64; p = 0.0001).

CONCLUSIONS

In patients with FM, magnesemia turned out to have inverse correlation with CRP and calcemia had positive association with triglycerides.

Cluster and Factor Analysis of Elements in Serum and Urine of Diabetic Patients with Peripheral Neuropathy and Healthy People

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus, presented as a major teratogenic cause worldwide. This study discussed alternation and correlation of magnesium (Mg), calcium (Ca), copper (Cu), zinc (Zn), iron (Fe), chromium (Cr), and selenium (Se) among DPN patients and healthy people using multivariate statistical analysis. Fifty patients with DPN were recruited from endocrinology department, First Hospital of Jilin University between January 2010 and October 2011 and also 50 healthy subjects were enrolled at the same time. Inductively coupled plasma mass spectrometry (ICP-MS) was used to assay elements in serum and urine. Cluster analysis was used to clarify alternation of elements' homogeneity. Factor analysis was performed to evaluate the most informative kinds of elements. Mg, Ca, Zn, and Cr in DPN patients were significantly lower in serum whereas significantly higher in urine. Elements were clustered into 4 or 5 clusters based on internal association using between-groups linkage algorithm. Serum Cr, Se, and Fe were grouped, and Mg related to Ca more closely in both serum and urine in DPN. Factor analysis revealed discrepancies of elements' contribution. Cr, Se, and Fe appeared to be the most crucial factors contributing to DPN. Mg, Ca, Zn, and Cu were more influential, whereas Cr became less potent to disease. Contributed value of elements could be determined and specified using loadings in scree plot. Future studies and delicate statistical models should be applied.

Diabetes, Diabetic Complications, and Phosphate Toxicity: A Scoping Review

This article presents a scoping review and synthesis of research findings investigating the toxic cellular accumulation of dysregulated inorganic phosphate-phosphate toxicity-as a pathophysiological determinant of diabetes and diabetic complications. Phosphorus, an essential micronutrient, is closely linked to the cellular metabolism of glucose for energy production, and serum inorganic phosphate is often transported into cells along with glucose during insulin therapy. Mitochondrial dysfunction and apoptosis, endoplasmic reticulum stress, neuronal degeneration, and pancreatic cancer are associated with dysregulated levels of phosphate in diabetes. Ectopic calcification involving deposition of calcium-phosphate crystals is prevalent throughout diabetic complications, including vascular calcification, nephropathy, retinopathy, and bone disorders. A low-glycemic, low-phosphate dietary intervention is proposed for further investigations in the treatment and prevention of diabetes and related diabetic pathologies.

Coagulatory Defects in Type-1 and Type-2 Diabetes

Diabetes (both type-1 and type-2) affects millions of individuals worldwide. A major cause of death for individuals with diabetes is cardiovascular diseases, in part since both types of diabetes lead to physiological changes that affect haemostasis. Those changes include altered concentrations of coagulatory proteins, hyper-activation of platelets, changes in metal ion homeostasis, alterations in lipid metabolism (leading to lipotoxicity in the heart and atherosclerosis), the presence of pro-coagulatory microparticles and endothelial dysfunction. In this review, we explore the different mechanisms by which diabetes leads to an increased risk of developing coagulatory disorders and how this differs between type-1 and type-2 diabetes.

Youth and Long-Term Dietary Calcium Intake With Risk of Impaired Glucose Metabolism and Type 2 Diabetes in Adulthood

CONTEXT

To the best of our knowledge, no previous studies have examined the role of youth calcium intake in the development of impaired glucose metabolism, especially those with long-term high calcium intake.

OBJECTIVES

To examine whether youth and long-term (between youth and adulthood) dietary calcium intake is associated with adult impaired glucose metabolism and type 2 diabetes (T2D).

DESIGN, SETTING, AND PARTICIPANTS

The Cardiovascular Risk in Young Finns Study is a 31-year prospective cohort study (n = 1134; age, 3 to 18 years at baseline).

EXPOSURES

Dietary calcium intake was assessed at baseline (1980) and adult follow-up visits (2001, 2007, and 2011). Long-term (mean between youth and adulthood) dietary calcium intake was calculated.

MAIN OUTCOME MEASURES

Adult impaired fasting glucose (IFG) and T2D.

RESULTS

We found no evidence for nonlinear associations between calcium intake and IFG or T2D among females and males (all P for nonlinearity > 0.05). Higher youth and long-term dietary calcium intake was not associated with the risk of IFG or T2D among females or males after adjustment for confounders, including youth and adult body mass index.

CONCLUSIONS

Youth or long-term dietary calcium intake is not associated with adult risk of developing impaired glucose metabolism or T2D.

Serum Calcium Concentrations, Chronic Inflammation and Glucose Metabolism: A Cross-Sectional Analysis in the Andhra Pradesh Children and Parents Study (APCaPS)

BACKGROUND

Evidence suggests a role for elevated serum calcium in dysregulated glucose metabolism, linked through low-level chronic inflammation.

OBJECTIVES

We investigated the association of elevated serum calcium concentrations (corrected for albumin) with markers of dysregulated glucose metabolism and type II diabetes and tested if these associations were accounted for by chronic inflammation in a rural Indian population.

METHODS

A cross-sectional analysis of participants aged 40-84 y from the Andhra Pradesh Children and Parents Study (APCaPS; n = 2699, 52.2% women) was conducted. Comprehensive information on household, sociodemographic, and lifestyle factors; medical and family history; physical measurements; blood measurements including fasting plasma glucose (FPG), fasting insulin (FI), serum calcium, albumin, phosphorous, vitamin D (in a subset), and creatinine were analyzed. Additionally, in a random sample of healthy participants (n = 1000), inflammatory biomarkers (interleukins 6 and 18, soluble intercellular adhesion molecule 1, adiponectin, and high-sensitivity C-reactive protein) were measured and an inflammatory score (IScore) calculated.

RESULTS

After adjustments for sociodemographics, lifestyle factors, and anthropometry the highest calcium quartile (Q4 compared with Q1) was associated with FI (β = 1.4 µU/ml; 95% CI: 1.2, 1.5 µU/ml; P-trend < 0.001), the homeostasis model assessment for insulin resistance (HOMA-IR) (β = 1.4; 95% CI: 1.2, 1.5; P-trend < 0.001), and was modestly associated with FPG (β = 2.1 mg/dL; 95% CI: -0.9, 5.2 mg/dL; P-trend = 0.058) and prevalent type II diabetes (OR = 1.6; 95% CI: 1.0, 2.6; P-trend= 0.020). In the healthy subgroup, the association of the highest calcium quartile was similar for FI and HOMA-IR. Additional adjustment with IScore did not alter the associations. Further, in a subset, all these associations were independent of endogenous regulators of calcium metabolism (serum vitamin D, phosphorus, and creatinine). Independently, after accounting for potential confounders, the highest IScore quartile (Q4 compared with Q1) was positively associated with FPG, FI, HOMA-IR, and prevalent prediabetes, and also with serum calcium concentrations in men.

CONCLUSIONS

Elevated serum calcium was positively associated with markers of dysregulated glucose metabolism and prevalent type II diabetes in a rural Indian population. Chronic inflammation did not mediate this association but was independently associated with markers of dysregulated glucose metabolism. Inflammation might be responsible for elevated serum calcium concentrations in men.

Low serum phosphate and magnesium levels are associated with peripheral neuropathy in patients with type 2 diabetes mellitus

AIMS

To determine the relationship of serum phosphate, serum magnesium and peripheral nerve function in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 254 patients diagnosed with T2DM were included. Peripheral nerve function was evaluated by nerve conduction study with the use of electromyography. Composite z scores of conduction velocity, latency, and amplitude were constructed, respectively. Demographic, medical and laboratory data including serum phosphate and magnesium were collected.

RESULTS

Serum phosphate and serum magnesium levels were significantly lower in patients with diabetic peripheral neuropathy (DPN) (P < 0.01). And the percentages of DPN patients were lower in high tertile of serum phosphate and serum magnesium (P < 0.05). Furthermore, composite z score of conduction velocity (CV) (P = 0.012) were positively associated with serum phosphate levels and the composite z score of amplitude (P < 0.001) and CV (P = 0.041) were positively associated with serum magnesium levels. After adjusting potential related factors (age, gender, smoking, diabetes duration, body mass index, systolic blood pressure, glycated hemoglobin, total cholesterol, estimated glomerular filtration rate), serum levels of phosphate and magnesium were still related to status of DPN in logistic regression (P < 0.05).

CONCLUSION

Lower serum phosphate and magnesium significantly correlated with parameters of nerve conduction in T2DM patients. Serum phosphate and magnesium might underlie the pathophysiologic features of DPN.

Salts and energy balance: A special role for dietary salts in metabolic syndrome

BACKGROUND

Dietary salts sodium (Na⁺), potassium (K⁺), magnesium (Mg2⁺), and calcium (Ca2⁺) are important in metabolic diseases. Yet, we do not have sufficient understanding on the salts global molecular network in these diseases. In this systematic review we have pooled information to identify the general effect of salts on obesity, insulin resistance and hypertension.

AIMS

To assess the roles of salts in metabolic disorders by focusing on their individual effect and the network effect among these salts.

METHODS

We searched articles in PubMed, EMBASE and Google Scholar. We selected original laboratory research, systematic reviews, clinical trials, observational studies and epidemiological data that focused on dietary salts and followed the preferred reporting items for systematic review in designing the present systematic review.

RESULTS

From the initial search of 2898 studies we selected a total of 199 articles that met our inclusion criteria and data extraction. Alterations in metabolic pathways associated with the sensitivity of sodium, potassium, magnesium and calcium may lead to obesity, hypertension, and insulin resistance. We found that the results of most laboratory research, animal studies and clinical trials are coherent but some research outcome are either inconsistent or inconclusive.

CONCLUSION

Important of salts in metabolic disorder is evident. In order to assess the effects of dietary salts in metablic diseases, environmental factors, dietary habits, physical activity, and the microbiome, should be considered in any study. Although interest in this area of research continues to grow, the challenge is to integrate the action of these salts in metabolic syndrom.

Intracellular calcium and NF-kB regulate hypoxia-induced leptin, VEGF, IL-6 and adiponectin secretion in human adipocytes

AIMS

Hypoxia-induced adipokine release has been attributed mainly to HIF-1α. Here we investigate the role of intracellular calcium and NF-kB in the hypoxia-dependent release of leptin, VEGF, IL-6 and the hypoxia-induced inhibition of adiponectin release in human adipocytes.

MAIN METHODS

We used intracellular calcium imaging to compare calcium status in preadipocytes and in adipocytes. We subjected both cell types to hypoxic conditions and measured the release of adipokines induced by hypoxia in the presence and absence of HIF-1α inhibitor YC-1, NF-_κB inhibitor SN50 and intracellular calcium chelator BAPTA-AM.

KEY FINDINGS

We demonstrate reduced intracellular calcium oscillations and increased oxidative stress as the cells transitioned from preadipocytes to adipocytes. We show that differentiation of preadipocytes to adipocytes is associated with distinct morphological changes in the mitochondria. We also show that hypoxia-induced secretion of leptin, VEGF, IL-6 and hypoxia-induced inhibition of adiponectin secretion are independent of HIF-1α expression. The hypoxia-induced leptin, VEGF and IL-6 release are [Ca⁺⁺]_i dependent whereas adiponectin is NF-_kB dependent.

SIGNIFICANCE

Our work suggests a major role for [Ca⁺⁺]_i in preadipocyte differentiation to adipocytes and that changes in mitochondrial morphology in the adipocytes might underlie the reduced calcium oscillations observed in the adipocytes. It also demonstrates that multiple signaling pathways are associated with the hypoxia-induced adipokine secretion.

Relação entre vitamina D e cálcio no desenvolvimento do Diabetes Mellitus tipo 1 e 2 - Uma revisão de literatura

A prevalência de obesidade, associada a hábitos alimentares inadequados e sedentarismo tem aumentado a ocorrência Diabetes Mellitus, tornando-se um problema de saúde pública. Perspectivas imediatas na mudança do ambiente para reverter o aumento dos níveis de obesidade não são promissores, e existe uma necessidade de considerar outras opções para prevenir o diabetes. Tem sido apontada uma associação inversa entre os baixos níveis da vitamina D e cálcio com a incidencia do Diabetes Mellitus. Desse modo, a vitamina D e o cálcio têm sido propostos como um possível agente terapêutico para a prevenção e tratamento da doença. O objetivo do estudo foi realizar uma revisão de literatura sobre a influência da vitamina D e do cálcio na fisiopatologia do diabetes mellitus, assim como no controle glicêmico.  Estudos têm mostrado que a vitamina D em conjunto com o cálcio são capazes de reduzirem o risco do desenvolvimento do diabetes mellitus tipo 2, enquanto que a insuficiência de vitamina D e de cálcio pode influenciar negativamente a glicemia. Além disso, nível plasmático de 25(OH)D, tem sido correlacionado com o diagnóstico de Diabetes Mellitus tipo 1. Evidências recentes demonstram que a concentração sérica de vitamina D e do cálcio podem estar relacionados ao diabetes. Entretanto, estudos prospectivos e de intervenção em humanos que comprovem a efetividade de ambos, tanto na prevenção como no tratamento dessa doença, ainda são necessários.

The Study on the Correlation Between Six Kinds of Mineral Elements and Diabetes

The study aimed to explore the relationship of six kinds of mineral elements and diabetes among adults in northeast China. A cross-sectional survey was conducted in Jilin Province, northeast China. A total of 366 males and 204 females aged 18 ~ 77 years from Jingyu town, Dongliao town, and Changling town were included using a multistage stratified random cluster sampling design. Data was obtained from face to face interview, physical examination, and laboratory measurement. We defined the normal people (3.9 ~ 6.0 mmol/L), impaired fasting glucose (IFG) individuals (6.1 ~ 6.9 mmol/L), and diabetes mellitus (DM) (> 7.0 mmol/L) according to the WHO diagnostic criteria. Kruskal-Wallis test, Spearman rank correlation, as well as binary logistic regression were used to analyze influencing factors. lg(Cu/Zn)was correlated with DM (OR 8.390; 95% CI of OR 1.272-55.347). The specific mineral elements such as Zn, Ca, as well as Cu/Zn ratio may be the potential risk factors for diabetes. So, the supplement or reduction of these elements is supposed to be told to IFG to prevent or delay the occurrence of diabetes or DM to avoid its complication.

Associations of serum calcium levels and dietary calcium intake with incident type 2 diabetes over 10 years: the Korean Genome and Epidemiology Study (KoGES)

BACKGROUND

Previous evidence regarding the associations between serum calcium concentrations, dietary calcium intake, and type 2 diabetes (T2D) is limited. We investigated the longitudinal associations of serum calcium levels and dietary calcium intake with T2D development.

METHODS

This study used data from the Ansung-Ansan cohort, a community-based, prospective cohort that was followed up for 10 years. Cox regression models adjusted for potential confounders were used to evaluate the associations of serum calcium levels (mean, 9.41 mg/dL) and dietary calcium intake (median, 389.59 mg/day) with T2D incidence. Association between dietary calcium intake and serum calcium levels was assessed using linear regression models.

RESULTS

Albumin-adjusted serum calcium levels were not associated with T2D risk (hazard ratio [HR] = 1.07, 95% confidence interval [CI] 0.96, 1.19, p-value = 0.2333). A one-unit increase in log-transformed, energy-adjusted dietary calcium intake was associated with a decreased risk of T2D (HR = 0.88, 95% CI 0.77, 1.00, p-value = 0.0460) and lower albumin-adjusted serum calcium levels (β = - 0.04, 95% CI - 0.07, - 0.02, p-value = 0.0014). The associations did not differ according to sex (all p-values for interaction > 0.10).

CONCLUSIONS

Serum calcium levels were not associated with T2D risk, while higher dietary calcium intake was associated with a decreased risk of T2D development. These results have public health implications for predicting and preventing T2D development, as well as providing guidelines for diet and calcium supplementation.

Dietary Calcium Intake May Contribute to the HOMA-IR Score in Korean Females with Vitamin D Deficiency (2008-2012 Korea National Health and Nutrition Examination Survey)

Background

Vitamin D and calcium are important factors involved in the regulation of blood glucose and insulin secretion. The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) score is a useful variable for evaluating insulin resistance, and therefore we cross-sectionally compared HOMA-IR scores according to serum vitamin D levels and dietary calcium intake.

Methods

We selected data from healthy males (n=5,163) and females (n=7,506) analyzed over 5 years (2008–2012) via the Korea National Health and Nutrition Examination Survey (KNHANES). We calculated HOMA-IR scores and compared them according to serum 25-hydroxyvitamin D (25(OH)D) concentration classification (<20, 20–30, >30 ng/mL) and dietary calcium quintile after adjustment for relevant variables using complex sample analysis. Comparisons were done after data weighting.

Results

The mean dietary calcium intake in males and females was 558.1 mg/day and 445.9 mg/day, respectively. The mean serum 25(OH)D concentration in males and females was 19.4 ng/mL and 16.8 ng/mL, respectively. After adjustment for relevant variables, HOMA-IR score was significantly correlated with serum 25(OH)D concentration and dietary calcium intake in females, whereas it was only correlated with serum 25(OH)D concentration in males. HOMA-IR was significantly lower in the top quintile of dietary calcium intake (mean, 866 mg/day) within females with vitamin D deficiency (P=0.047).

Conclusion

Adequate dietary calcium intake may be important for normal HOMA-IR in females with vitamin D deficiency.

Serum calcium changes and risk of type 2 diabetes mellitus in Asian population

AIMS

We examined the association between changes in serum calcium levels with the incidence of type 2 diabetes mellitus (T2DM) in apparently healthy South Korean subjects.

METHODS

A retrospective longitudinal analysis was conducted with subjects who had participated in comprehensive health check-ups at least four times over a 7-year period (between 2006 and 2012). In total, 23,121 subjects were categorized into tertiles based on changes in their albumin-adjusted serum calcium levels. Multivariate Cox regression models were fitted to assess the association between changes in serum calcium levels during follow-up and the relative risk of diabetes incidence.

RESULTS

After a median follow-up of 57.4months, 1,929 (8.3%) new cases of T2DM occurred. Simple linear regression analysis showed serum calcium level changes correlated positively with changes in HbA1c and fasting plasma glucose (FPG) levels (B=5.72, p<0.001 for FPG; B=0.13, p<0.001 for HbA1c). An increase in albumin-adjusted serum calcium levels during follow-up was related to an increased risk of T2DM. After adjustment for potential confounders, the risk of T2DM was 1.6 times greater for subjects whose albumin-adjusted serum calcium levels were in the highest change tertile during follow-up than for subjects whose levels were in the lowest tertile (HR 1.65, 95% CI 1.44-1.88, P<0.001).

CONCLUSIONS

The elevation of albumin-adjusted serum calcium levels was associated with an increased risk of T2DM, independent of baseline glycemic status.

Dietary Food-Additive Phosphate and Human Health Outcomes

Dietary intake of phosphorus is required for human health, and dietary reference intakes for phosphorus have been established. Food-grade phosphates are used as additives to provide a wide range of technical functions in food production. Phosphates are often the most efficient ingredients to provide the required functionality in many applications, and in some cases, there are not effective and approved alternatives. However, many investigators have expressed concern about the quantities of phosphorus and food-additive phosphate present in the diets of many populations. This paper presents the outcome of an extensive review of 110 primary research articles focused on identifying evidence that substantiates or refutes associations of total dietary phosphorus and food-additive phosphate intake with health and disease in humans. The lack of conclusive evidence prevented the drawing of firm conclusions about the safety and possible risks of food-additive phosphate in the general population, which is consonant with the overall assessments of authoritative institutions who have concluded that available data are insufficient to make the required determinations. Despite the inadequacy of the evidence currently available, many of the authors of the publications reviewed for this paper expressed concerns about the quantities of phosphorus and food-additive phosphate in the diets of the populations and subpopulations they studied. At the same time, most of these authors offered only qualified conclusions and expressed themselves tentatively. In addition, authors of primary research publications, authors of review articles, and authoritative institutions have called for the conduct of further research.

Serum Trace Elements and Electrolytes Are Associated with Fasting Plasma Glucose and HbA1c in Postmenopausal Women with Type 2 Diabetes Mellitus

The primary aim of the research was to assess the level of trace elements and electrolytes in serum of postmenopausal diabetic women. Sixty-four postmenopausal women with type 2 diabetes mellitus (DM2) and 64 age- and body mass index-matched controls were examined. Serum trace elements were assessed using inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS). Fasting plasma glucose (FPG) and glycated hemoglobin (HbA_1c) levels were evaluated using Randox kits. The obtained data demonstrate that DM2 patients were characterized by 42 and 34 % higher FPG and HbA_1c levels, respectively (p < 0.001). The level of Cu and Se in diabetic postmenopausal women was increased by 10 and 15 % in comparison to the respective control values (p = 0.002 and <0.001). Serum Mn, Zn, and Ni concentrations were lower than the control ones by 32 % (p = 0.003), 8 % (p = 0.003), and 23 % (p = 0.046), respectively. FPG and HbA_1c levels directly correlated with serum Se (p < 0.001) and Cu (p = 0.014 and p = 0.028) concentrations and inversely related to Zn (p < 0.001) and Tl (p = 0.023 and p = 0.029) levels. Multiple regression analysis demonstrated a significant association between serum Zn and Se and FPG and HbA_1c levels. It is proposed that Zn and Se play an important role in DM2 pathogenesis. Further studies are required to assess the intimate mechanisms of the observed differences.

Serum Calcium and the Risk of Incident Metabolic Syndrome: A 4.3-Year Retrospective Longitudinal Study

BACKGROUND

An association between serum calcium level and risk of metabolic syndrome (MetS) has been suggested in cross-sectional studies. This study aimed to evaluate the association between baseline serum calcium level and risk of incident MetS in a longitudinal study.

METHODS

We conducted a retrospective longitudinal study of 12,706 participants without MetS who participated in a health screening program, had normal range serum calcium level at baseline (mean age, 51 years), and were followed up for 4.3 years (18,925 person-years). The risk of developing MetS was analyzed according to the baseline serum calcium levels.

RESULTS

A total of 3,448 incident cases (27.1%) of MetS developed during the follow-up period. The hazard ratio (HR) for incident MetS did not increase with increasing tertile of serum calcium level in an age- and sex-matched model (P for trend=0.915). The HRs (95% confidence interval [CI]) for incident MetS comparing the second and the third tertiles to the first tertile of baseline serum calcium level were 0.91 (95% CI, 0.84 to 0.99) and 0.85 (95% CI, 0.78 to 0.92) in a fully adjusted model, respectively (P for trend=0.001). A decreased risk of incident MetS in higher tertiles of serum calcium level was observed in subjects with central obesity and/or a metabolically unhealthy state at baseline.

CONCLUSION

There was no positive correlation between baseline serum calcium levels and incident risk of MetS in this longitudinal study. There was an association between higher serum calcium levels and decreased incident MetS in individuals with central obesity or two components of MetS at baseline.

Association of serum calcium and heart failure with preserved ejection fraction in patients with type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a recognized trigger factor for heart failure with preserved ejection fraction (HFpEF). Recent studies show that higher serum calcium level is associated with greater risk of both T2DM and heart failure. We speculate that increased serum calcium is related to HFpEF prevalence in patients with T2DM.

METHODS

In this cross-sectional echocardiographic study, 807 normocalcemia and normophosphatemia patients with T2DM participated, of whom 106 had HFpEF. Multinomial logistic regression was carried out to determine the variables associated with HFpEF. The associations between serum calcium and metabolic parameters, as well as the rate of HFpEF were examined using bivariate linear correlation and binary logistic regression, respectively. The predictive performance of serum calcium for HFpEF was evaluated using the area under the receiver operating characteristic curve (AUC).

RESULTS

Patients with HFpEF have significantly higher serum calcium than those without HFpEF. Serum calcium was positively associated with total cholesterol, triglycerides, low-density lipoprotein cholesterol, serum uric acid, HOMA-IR and fasting plasma glucose. Compared with patients in the lowest serum calcium quartile, the odds ratio (OR) for HFpEF in patients in the highest quartile was 2.331 (95 % CI 1.088-4.994, p = 0.029). When calcium was analyzed as a continuous variable, per 1 mg/dL increase, the OR (95 % CI) for HFpEF was [2.712 (1.471-5.002), p = 0.001]. Serum calcium can predict HFpEF [AUC = 0.673, 95 % CI (0.620-0.726), p < 0.001].

CONCLUSIONS

An increase in serum calcium level is associated with an increased risk of HFpEF in patients with T2DM.

Serum calcium and incident type 2 diabetes: the Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND

Elevated serum calcium has been associated with a variety of metabolic abnormalities and may be associated with a greater risk of diabetes.

OBJECTIVE

The purpose of this study was to test the hypothesis that serum calcium concentration is positively and independently associated with the incidence of diabetes and to evaluate the association of calcium-sensing receptor (CaSR) gene single nucleotide polymorphism (SNP) rs1801725 with incident diabetes.

DESIGN

Atherosclerosis Risk in Communities study participants free of diabetes at baseline (n = 12,800; mean age: 53.9 y; 22.6% black) were studied for incident diabetes. Serum calcium was measured at baseline and corrected for serum albumin. Diabetes was defined by use of glucose concentrations, self-report, or medication use. Cox proportional hazards regression was used.

RESULTS

During a mean 8.8 y of follow-up, 1516 cases of diabetes were reported. Participants in the highest compared with lowest calcium quintile were at greater risk of incident diabetes after adjustment for demographic and lifestyle factors [HR (95% CI): 1.34 (1.14, 1.57); P-trend across quintiles <0.0001] and with further adjustment for waist circumference and body mass index [1.26 (1.07, 1.48); P-trend = 0.004]. Additional adjustment for biomarkers on the metabolic pathway (e.g., 25-hydroxyvitamin D, parathyroid hormone, phosphorus) had little impact. The calcium-diabetes association was statistically significant in blacks [1.48 (1.11, 1.98); P-trend = 0.002] but not whites [1.17 (0.96, 1.43); P-trend = 0.17] after adjustment for adiposity. In whites, CaSR gene SNP rs1801725 was associated with serum calcium but not with risk of diabetes.

CONCLUSIONS

Consistent with 3 previous cohort studies, elevated serum calcium was found to be associated with a greater risk of type 2 diabetes. Further research is needed to understand the role, if any, that calcium plays in the pathogenesis of diabetes.

Intracellular alkalinization by phosphate uptake via type III sodium-phosphate cotransporter participates in high-phosphate-induced mitochondrial oxidative stress and defective insulin secretion

Elevated plasma levels of inorganic phosphate (P_i) are harmful, causing, among other complications, vascular calcification and defective insulin secretion. The underlying molecular mechanisms of these complications remain poorly understood. We demonstrated the role of P_i transport across the plasmalemma on P_i toxicity in INS-1E rat clonal β cells and rat pancreatic islet cells. Type III sodium-phosphate cotransporters (NaP_is) are the predominant P_i transporters expressed in insulin-secreting cells. Transcript and protein levels of sodium-dependent phosphate transporter 1 and 2 (PiT-1 and -2), isotypes of type III NaP_i, were up-regulated by high-P_i incubation. In patch-clamp experiments, extracellular P_i elicited a Na⁺-dependent, inwardly rectifying current, which was markedly reduced under acidic extracellular conditions. Cellular uptake of P_i elicited cytosolic alkalinization; intriguingly, this pH change facilitated P_i transport into the mitochondrial matrix. Increased mitochondrial P_i uptake accelerated superoxide generation, mitochondrial permeability transition (mPT), and endoplasmic reticulum stress-mediated translational attenuation, leading to reduced insulin content and impaired glucose-stimulated insulin secretion. Silencing of PiT-1/2 prevented P_i-induced superoxide generation and mPT, and restored insulin secretion. We propose that P_i transport across the plasma membrane and consequent cytosolic alkalinization could be a therapeutic target for protection from P_i toxicity in insulin-secreting cells, as well as in other cell types.-Nguyen, T. T., Quan, X., Xu, S., Das, R., Cha, S.-K., Kong, I. D., Shong, M., Wollheim, C. B., Park, K.-S. Intracellular alkalinization by phosphate uptake via type III sodium-phosphate cotransporter participates in high-phosphate-induced mitochondrial oxidative stress and defective insulin secretion.

Association of serum calcium concentrations with fibrinogen and homocysteine in nondiabetic Korean subjects

Considerable evidence shows that increased serum calcium levels are associated with metabolic disorders, cardiovascular disease, and increased mortality. This study investigated whether serum calcium, within a normal range, is significantly associated with serum fibrinogen and homocysteine, markers of increased cardiovascular disease risk in nondiabetic Korean subjects.A cross-sectional analysis was performed on 1096 subjects (mean age, 55.1 ± 11.1 years; 36.1% women) undergoing a general health checkup. Serum biochemistry was analyzed including serum albumin-corrected calcium (Cac), insulin resistance (IR, using homeostasis model assessment [HOMA]), fibrinogen, and homocysteine.Compared with patients within the lowest Cac quartile, those with higher Cac levels had increased fibrinogen and homocysteine levels as well as an increased proportion of smoking, dyslipidemia, and HOMA-IR. Correlation analyses revealed linear relationships for Cac with fibrinogen and homocysteine in both genders. After adjustment for confounding factors, serum Cac was significantly associated with high fibrinogen (odds ratio [OR] for the highest vs the lowest quartile = 1.76, 95% confidence interval [CI] = 1.09-2.83, P = 0.02) and homocysteine (OR = 1.83, 95% CI = 1.07-3.11, P = 0.027). Multivariate regression models showed that Cac was linearly associated with fibrinogen (standardized β = 0.14, P < 0.001) and homocysteine (standardized β = 0.07, P = 0.009).High normal calcium concentrations were independently associated with increased levels of fibrinogen and homocysteine. Further investigation is needed to validate whether slightly increased calcium levels within the normal range indicate a higher risk of cardiovascular disease.

Circulating calcium concentrations, vascular disease and mortality: a systematic review

Associations between serum calcium and vascular disease have been reported, but the consistency of these findings is unknown. We conducted a systematic review to determine whether circulating calcium concentrations are associated with risks of cardiovascular disease and death in normocalcaemic populations. We conducted PubMed searches up to 18 December 2014 and scrutinized reference lists of papers. Eligible studies related serum calcium to mortality or cardiovascular events in humans. A follow-up of at least one year was required for longitudinal studies. Studies in populations selected on the basis of renal disease or abnormal serum calcium were excluded. Two investigators performed independent data extraction. The results were tabulated and, where possible, meta-analysed. Five of 11 studies reported a statistically significant positive association between serum calcium and mortality. Meta-analysis of eight of these studies showed a hazard ratio of death of 1.13 (1.09, 1.18) per standard deviation of serum calcium. Eight of 13 studies reported a statistically significant positive association between serum calcium and cardiovascular disease. Meta-analysis of eight studies showed a hazard ratio of cardiovascular disease of 1.08 (1.04, 1.13) per standard deviation of serum calcium. For two studies reporting odds ratios, the pooled odds ratio per standard deviation was 1.22 (1.11, 1.32). When hazard ratios adjusted for cardiovascular risk factors were meta-analysed, the pooled hazard ratio was 1.04 (1.01, 1.08). Other studies demonstrated associations between serum calcium and stroke and between serum calcium and direct measurements of arterial disease and calcification. These observational data indicate that serum calcium is associated with vascular disease and death, but they cannot determine causality.

Serum calcium and incident diabetes: an observational study and meta-analysis

The study aimed to prospectively evaluate if serum calcium is related to diabetes incidence in Hong Kong Chinese. The results showed that serum calcium has a significant association with increased risk of diabetes. The result of meta-analysis reinforced our findings.

INTRODUCTION

This study aimed to evaluate the association of serum calcium, including serum total calcium and albumin-corrected calcium, with incident diabetes in Hong Kong Chinese.

METHODS

We conducted a retrospective cohort study in 6096 participants aged 20 or above and free of diabetes at baseline. Serum calcium was measured at baseline. Incident diabetes was determined from several electronic databases. We also searched relevant databases for studies on serum calcium and incident diabetes and conducted a meta-analysis using fixed-effect modeling.

RESULTS

During 59,130.9 person-years of follow-up, 631 participants developed diabetes. Serum total calcium and albumin-corrected calcium were associated with incident diabetes in the unadjusted model. After adjusting for demographic and clinical variables, the association remained significant only for serum total calcium (hazard ratio (HR), 1.32 (95 % confidence interval (CI), 1.02-1.70), highest vs. lowest quartile). In a meta-analysis of four studies including the current study, both serum total calcium (pooled risk ratio (RR), 1.38 (95 % CI, 1.15-1.65); I (2) = 5 %, comparing extreme quantiles) and albumin-corrected calcium (pooled RR, 1.29 (95 % CI, 1.03-1.61); I (2) = 0 %, comparing extreme quantiles) were associated with incident diabetes. Penalized regression splines showed that the association of incident diabetes with serum total calcium and albumin-correlated calcium was non-linear and linear, respectively.

CONCLUSIONS

Elevated serum calcium concentration is associated with incident diabetes. The mechanism underlying this association warrants further investigation.

Mitochondrial oxidative stress mediates high-phosphate-induced secretory defects and apoptosis in insulin-secreting cells

Inorganic phosphate (Pi) plays an important role in cell signaling and energy metabolism. In insulin-releasing cells, Pi transport into mitochondria is essential for the generation of ATP, a signaling factor in metabolism-secretion coupling. Elevated Pi concentrations, however, can have toxic effects in various cell types. The underlying molecular mechanisms are poorly understood. Here, we have investigated the effect of Pi on secretory function and apoptosis in INS-1E clonal β-cells and rat pancreatic islets. Elevated extracellular Pi (1~5 mM) increased the mitochondrial membrane potential (ΔΨm), superoxide generation, caspase activation, and cell death. Depolarization of the ΔΨm abolished Pi-induced superoxide generation. Butylmalonate, a nonselective blocker of mitochondrial phosphate transporters, prevented ΔΨm hyperpolarization, superoxide generation, and cytotoxicity caused by Pi. High Pi also promoted the opening of the mitochondrial permeability transition (PT) pore, leading to apoptosis, which was also prevented by butylmalonate. The mitochondrial antioxidants mitoTEMPO or MnTBAP prevented Pi-triggered PT pore opening and cytotoxicity. Elevated extracellular Pi diminished ATP synthesis, cytosolic Ca(2+) oscillations, and insulin content and secretion in INS-1E cells as well as in dispersed islet cells. These parameters were restored following preincubation with mitochondrial antioxidants. This treatment also prevented high-Pi-induced phosphorylation of ER stress proteins. We propose that elevated extracellular Pi causes mitochondrial oxidative stress linked to mitochondrial hyperpolarization. Such stress results in reduced insulin content and defective insulin secretion and cytotoxicity. Our data explain the decreased insulin content and secretion observed under hyperphosphatemic states.

Association between direct measurement of active serum calcium and risk of type 2 diabetes mellitus: A prospective study

BACKGROUND AND AIMS

Previous prospective studies showing a positive association between serum calcium and incidence of type 2 diabetes mellitus (T2DM) have relied on total calcium or an indirect estimate of active, ionized calcium (iCa). We aimed to assess this relationship using a direct measurement of iCa.

METHODS AND RESULTS

iCa and cardiometabolic risk factors were measured in a population-based sample of 2350 men without a known history of T2DM at baseline. Associations between iCa levels and incident cases of T2DM (self-reported, ascertained with a glucose tolerance test, or determined by record linkage to national registers) were estimated using Cox regression analyses adjusted for potential confounders. At baseline, mean (standard deviation) age was 53 (5) years and mean iCa 1.18 (0.05) mmol/L. During a median follow-up of 23.1 years, 140 new cases of T2DM were recorded. In a multivariable analysis adjusted for age, body mass index, systolic blood pressure, serum HDL-cholesterol, and family history of T2DM, there was no association comparing second (hazard ratio 0.84; 95% confidence interval 0.59-1.18), third (0.77; 0.52-1.14), or fourth (0.98; 0.69-1.39) vs first quartile of iCa (p for trend 0.538); further adjustment for C-reactive protein, physical activity level, and triglycerides did not change the estimates (p for trend 0.389).

CONCLUSION

In this study, we did not find evidence of an association between direct measurement of active calcium and risk of T2DM. Further studies are needed to confirm our findings and define the relationship between factors influencing indirect calcium estimation and incident T2DM.