Dietary Nonheme, Heme, and Total Iron Intake and the Risk of Diabetes in Adults: Results From the China Health and Nutrition Survey

Association of dietary iron intake with diabetic kidney disease among individuals with diabetes

PURPOSE

The current study investigated the correlation between dietary iron intake and diabetic kidney disease among diabetic adults.

METHODS

This cross-sectional study enrolled 8118 participants who suffered from diabetes from the National Health and Nutrition Examination Survey (NHANES) 1999-2018. Dietary iron intake was obtained from 24 h recall interviews, and diabetic kidney disease was defined as eGFR < 60 mL/min per 1.73 m2 or albumin creatinine ratio (ACR) ≥ 30 mg/g. Three weighted logistic regression models were utilized to investigate odd ratio (OR) and 95% CIs for diabetic kidney disease. Stratified analyses were performed by gender, age, BMI, HbA1c, hypertension status, and smoking status, and diabetes types.

RESULTS

Among 8118 participants (51.6% male, mean age 61.3 years), 40.7% of participants suffered from diabetic kidney disease. With the adjustment of potential covariates, we found that ≥ 12.59 mg of dietary iron was related to a lower risk of diabetic kidney disease (OR = 0.78, 95% CI: 0.63 to 0.96; OR = 0.79, 95% CI: 0.63 to 0.98). In stratified analyses, higher iron intake was negatively related to diabetic kidney disease, especially among those who were male, < 60 years, those with hypertension, those with HbA1c < 7.0%, and those who were ex-smokers. The result remained robust in sensitivity analyses.

CONCLUSION

We found that ≥ 12.59 mg of dietary iron is associated with a lower risk of diabetic kidney disease, especially in those who were male, younger, heavier weight, have better blood sugar control, and those who were ex-smokers.

Associations between dietary iron intake from different sources and non-alcoholic fatty liver disease in adults

BACKGROUND AND OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) has become a worldwide public health problem. Current evidence on the association between dietary iron intake and the risk of NAFLD is limited. The present study aimed to investigate the associations of animal-derived dietary iron (ADDI) intake, plant-derived dietary iron (PDDI) intake, and the ratio of PDDI:ADDI with NAFLD risk among U.S. adult population.

METHODS AND STUDY DESIGN

This was a repeated cross-sectional study. Data were collected from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. NAFLD was defined as a United States Fatty Lives Index ≥30, and dietary iron intake was assessed through two 24-h dietary recall in-terviews. Logistic regression and restricted cubic spline models were applied to examine the associations between dietary iron intake from different sources and NAFLD risk.

RESULTS

A total of 9478 participants aged ≥20 years were enrolled in the present study. After adjustment for multiple confounding factors, relative to the lowest quartile, the odds ratio (OR) and 95% confidence interval (CI) of NAFLD for the highest quartile was 1.01(95% CI, 0.82-1.24) for ADDI intake, 0.82 (95% CI, 0.64-0.99) for PDDI intake, and 1.00 (95% CI, 0.81-1.24) for the PDDI: ADDI intake ratio. In stratified analysis by sex and age, the significantly negative associations of PDDI intake with NAFLD was observed in women and participants older than 45 years. Dose-response analyses indicated that NAFLD was negatively associated with PDDI intake in a non-linear manner.

CONCLUSIONS

PDDI intake was negatively associated with NAFLD in U.S. adults.

A Bayesian network analysis of the probabilistic relationships between metabolically healthy obesity and cardiovascular disease risk under new diagnostic criteria

BACKGROUND

The relationship between metabolically healthy obesity (MHO) and cardiovascular disease (CVD) risk remains debated. The critical point may be the lack of consensus on MHO's definition and diagnostic criteria.

OBJECTIVE

This study aimed to investigate the association of MHO status with arteriosclerosis-CVD (ASCVD) risk in Chinese under new diagnostic criteria.

METHODS

Participants aged 35-79 in the 2009 China Health and Nutrition Survey cohort were included. The 10-year ASCVD risk was predicted by the prediction for ASCVD risk in China, and participants with a predicted risk of ⩾ 10% were classified into the high-risk group. The Bayesian network (BN) models were constructed to characterize the multivariable probabilistic connections between metabolically obesity phenotypes and ASCVD risk.

RESULTS

The 10-year ASCVD risk score and the proportion of individuals at ASCVD high risk were significantly different between metabolically obesity phenotypes (P< 0.001). BN reasoning results showed that MHO individuals were not significantly associated with a 10-year ASCVD risk. Among metabolically unhealthy individuals, the conditional probability of high ASCVD risk increased with the Body Mass Index (BMI), with the conditional probability of high ASCVD risk was 24.63% (95% CI: 22.81-26.55%), 32.97% (95% CI: 30.75-35.27%) and 40.2% (95% CI: 36.64-43.86%) for metabolically unhealthy normal weight (MUNW), metabolically healthy overweight weight (MHOW), and metabolically unhealthy obesity (MUO) group, respectively. Subgroup analysis showed that MHO individuals were at increased risk of CVD compared with metabolically healthy normal weight (MHNW) individuals only in females.

CONCLUSION

These results showed that there was no significant increase in ASCVD risk of MHO phenotype based on the new diagnostic criteria, suggesting that MHO is in a relatively healthy state.

Dietary iron intake predicts all-cause and cardiovascular mortality in patients with diabetes

BACKGROUND

Limited data exists on the link between dietary iron intake and mortality in diabetes. Our investigation aimed to explore how dietary iron intake correlates with overall and cause-specific mortality in diabetic individuals.

METHODS

This analysis encompassed 5970 participants with diabetes from the National Health and Nutrition Examination Survey spanning 1999 to 2014. Baseline data were collected through surveys and examinations, with mortality status tracked via National Death Index records until December 31, 2015. Cox proportional hazard models were utilized to calculate hazard ratios (HR) and 95% confidence intervals (CI) for mortality from various causes, including cardiovascular disease (CVD) and cancer.

RESULTS

The average iron intake among the cohort was 14.1 ± 7.4 mg daily, with an average participant age of 61.3 and 3059 (51.3%) male adults. Over 41,425 person-years of follow-up, 1497 deaths were recorded. Following adjustments for multiple variables, an iron intake between 11.1 and 14.4 mg was associated with the lowest risk of all-cause mortality (HR 0.83 [0.70, 0.99], P < 0.05) compared to the reference group (<8.3 mg). Analysis of dose-response curves revealed an L-shaped pattern in men and a J-shaped pattern in women concerning the relationship between iron intake and all-cause mortality.

CONCLUSIONS

Our findings suggest a nonlinear association between dietary iron intake and all-cause mortality in individuals with diabetes. Specifically, higher iron intake may increase all-cause mortality risk in men, while potentially exert a protective effect in women.

Scientific opinion on the tolerable upper intake level for iron

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the tolerable upper intake level (UL) for iron. Systematic reviews were conducted to identify evidence regarding high iron intakes and risk of chronic diseases, adverse gastrointestinal effects and adverse effects of iron supplementation in infancy, young childhood and pregnancy. It is established that systemic iron overload leads to organ toxicity, but no UL could be established. The only indicator for which a dose-response could be established was black stools, which reflect the presence of large amounts of unabsorbed iron in the gut. This is a conservative endpoint among the chain of events that may lead to systemic iron overload but is not adverse per se. Based on interventions in which black stools did not occur at supplemental iron intakes of 20-25 mg/day (added to a background intake of 15 mg/day), a safe level of intake for iron of 40 mg/day for adults (including pregnant and lactating women) was established. Using allometric scaling (body weight0.75), this value was scaled down to children and adolescents and safe levels of intakes between 10 mg/day (1-3 years) and 35 mg/day (15-17 years) were derived. For infants 7-11 months of age who have a higher iron requirement than young children, allometric scaling was applied to the supplemental iron intakes (i.e. 25 mg/day) and resulted in a safe level of supplemental iron intake of 5 mg/day. This value was extended to 4-6 month-old infants and refers to iron intakes from fortified foods and food supplements, not from infant and follow-on formulae. The application of the safe level of intake is more limited than a UL because the intake level at which the risk of adverse effects starts to increase is not defined.

Triceps skinfold thickness trajectories and the risk of all-cause mortality: A prospective cohort study

BACKGROUND

The measurement of triceps skinfold (TSF) thickness serves as a noninvasive metric for evaluating subcutaneous fat distribution. Despite its clinical utility, the TSF thickness trajectories and their correlation with overall mortality have not been thoroughly investigated.

AIM

To explore TSF thickness trajectories of Chinese adults and to examine their associations with all-cause mortality.

METHODS

This study encompassed a cohort of 14747 adults sourced from the China Health and Nutrition Survey. Latent class trajectory modeling was employed to identify distinct trajectories of TSF thickness. Subjects were classified into subgroups reflective of their respective TSF thickness trajectory. We utilized multivariate Cox regression analyses and mediation examinations to explore the link between TSF thickness trajectory and overall mortality, including contributory factors.

RESULTS

Upon adjustment for multiple confounding factors, we discerned that males in the 'Class 2: Thin-stable' and 'Class 3: Thin-moderate' TSF thickness trajectories exhibited a markedly reduced risk of mortality from all causes in comparison to the 'Class 1: Extremely thin' subgroup. In the mediation analyses, the Geriatric Nutritional Risk Index was found to be a partial intermediary in the relationship between TSF thickness trajectories and mortality. For females, a lower TSF thickness pattern was significantly predictive of elevated all-cause mortality risk exclusively within the non-elderly cohort.

CONCLUSION

In males and non-elderly females, lower TSF thickness trajectories are significantly predictive of heightened mortality risk, independent of single-point TSF thickness, body mass index, and waist circumference.

Effects of T2DM on postoperative outcome of patients with colorectal cancer: a study on the relationship between blood glucose control and survival rate

To investigate the impact of type 2 diabetes (T2DM) on the prognosis of colorectal cancer (CRC). The data of 312 patients with CRC treated in the First Affiliated Hospital of Huzhou University from 2012 to 2018 were analyzed retrospectively. The patients were divided into a comorbidity group (n = 62) and a non-comorbidity group (n = 250) according to the presence of T2DM. The baseline data of the two groups were balanced by 1:2 propensity score matching (PSM). Kaplan-Meier analysis and Log-rank test were employed to compare the 5-year overall survival (OS) rates of patients. Cox regression model and inverse probability of treatment weighting (IPTW) were utilized to assess the influence of T2DM on 5-year OS of patients. Based on the results of Cox regression, a nomogram model of T2DM on 5-year OS of patients was constructed. A total of 62 patients in the comorbidity group and 124 patients in the non-comorbidity group were matched using PSM. The 5-year OS rate was lower in the comorbidity group than in the non-comorbidity group (82.23% VS 90.32%, P = 0.038). Subgroup analysis showed that the 5-year overall survival rate was higher in the good blood glucose control group than in the poor blood glucose control group (97.14% VS 62.96%, P<0.01). Multivariate Cox regression showed that the 5-year mortality risk in the comorbidity group was 2.641 times higher than that in the non-comorbidity group (P = 0.026). IPTW analysis showed that the 5-year risk of death in the comorbidity group was 2.458 times that of the non-comorbidity group (P = 0.019). The results showed that poor blood glucose control, BMI≥25 kg/m2, low differentiation, III/IV stage, and postoperative infection were independent factors affecting the 5-year overall survival rate of CRC patients (P<0.05). The ROC curve showed that the AUCs of the constructed model in predicting the 5-year OS in the training set and the testing set were 0.784 and 0.776, respectively. T2DM is identified as a risk factor for reduced 5-year survival among CRC patients, necessitating increased attention for this subgroup, particularly those with poor blood glucose control.

Relationship between trajectories of dietary iron intake and risk of type 2 diabetes mellitus: evidence from a prospective cohort study

BACKGROUND

The association between dietary iron intake and the risk of type 2 diabetes mellitus (T2DM) remains inconsistent. In this study, we aimed to investigate the relationship between trajectories of dietary iron intake and risk of T2DM.

METHODS

This study comprised a total of 61,115 participants without a prior T2DM from the UK Biobank database. We used the group-based trajectory model (GBTM) to identify different dietary iron intake trajectories. Cox proportional hazards models were used to evaluate the relationship between trajectories of dietary iron intake and risk of T2DM.

RESULTS

During a mean follow-up of 4.8 years, a total of 677 T2DM events were observed. Four trajectory groups of dietary iron intake were characterized by the GBTM: trajectory group 1 (with a mean dietary iron intake of 10.9 mg/day), 2 (12.3 mg/day), 3 (14.1 mg/day) and 4 (17.6 mg/day). Trajectory group 3 was significantly associated with a 38% decreased risk of T2DM when compared with trajectory group 1 (hazard ratio [HR] = 0.62, 95% confidence interval [CI]: 0.49-0.79), while group 4 was significantly related with a 30% risk reduction (HR = 0.70, 95% CI: 0.54-0.91). Significant effect modifications by obesity (p = 0.04) and history of cardiovascular disease (p < 0.01) were found to the relationship between trajectories of dietary iron intake and the risk of T2DM.

CONCLUSIONS

We found that trajectories of dietary iron intake were significantly associated with the risk of T2DM, where the lowest T2DM risk was observed in trajectory group 3 with a mean iron intake of 14.1 mg/day. These findings may highlight the importance of adequate dietary iron intake to the T2DM prevention from a public health perspective. Further studies to assess the relationship between dietary iron intake and risk of T2DM are needed, as well as intervention studies to mitigate the risks of T2DM associated with dietary iron changes.

Antioxidant Minerals Modified the Association between Iron and Type 2 Diabetes in a Chinese Population

Inconsistent findings exist regarding the relationship between heme iron intake and type 2 diabetes (T2D) among Western and Eastern populations. Easterners tend to consume a plant-based diet which is abundant in antioxidant minerals. To examine the hypothesis that antioxidant mineral may modify the relationship between iron and T2D, we performed a case-control study by measuring the serum mineral levels in 2198 Chinese subjects. A total of 2113 T2D patients and 2458 controls were invited; 502 T2D patients and 1696 controls were finally analyzed. In the total population, high serum iron showed a positive association with T2D odds (odds ratio [OR] = 1.27 [1.04, 1.55]); high magnesium (OR = 0.18 [0.14, 0.22]), copper (OR = 0.27 [0.21, 0.33]), zinc (OR = 0.37 [0.30, 0.46]), chromium (OR = 0.61 [0.50, 0.74]), or selenium concentrations (OR = 0.39 [0.31, 0.48]) were inversely associated with T2D odds. In contrast, in individuals with higher magnesium (>2673.2 µg/dL), zinc (>136.7 µg/dL), copper (>132.1 µg/dL), chromium (>14.0 µg/dL), or selenium concentrations (>16.8 µg/dL), serum iron displayed no association with T2D (p > 0.05). Serum copper and magnesium were significant modifiers of the association between iron and T2D in individuals with different physiological status (p < 0.05). Our findings support the idea that consuming a diet rich in antioxidant minerals is an effective approach for preventing T2D.

L-shaped association between dietary coenzyme Q10 intake and high-sensitivity C-reactive protein in Chinese adults: a national cross-sectional study

Background: Chronic inflammation contributes to the occurrence and progression of many diseases. Most previous clinical studies have explored the effect of high-dose CoQ10 supplements on inflammation. Food is another important source of CoQ10, but the relationship between the intake of CoQ10 from dietary sources and inflammation was unknown. We aimed to explore the dose-response association between the intake of dietary-derived CoQ10 and inflammation-related biomarkers. Methods: Seven thousand nine hundred and fifty-three Chinese adults from the China Health and Nutrition Survey (CHNS) were the subjects of this cross-sectional investigation. Dietary CoQ10 intake was assessed using dietary information from three days. High-sensitivity C-reactive protein (hsCRP) and white blood cell count (WBC) were assessed using fasting venous blood. Results: In an adjusted linear regression model, CoQ10 consumption from dietary sources was inversely associated with hsCRP, with effect sizes in each group: Q2 (β = -0.85 mg L-1, 95% CI: -1.43 to -0.28 mg L-1, P = 0.004), Q3 (β = -0.70 mg L-1, 95% CI: -1.28 to -0.12 mg L-1, P = 0.017), and Q4 (β = -0.79 mg L-1, 95% CI: -1.39 to -0.19 mg L-1, P = 0.010). Moreover, restricted cubic splines (RCS) revealed a non-linear L-shaped association between dietary-derived CoQ10 consumption and hsCRP (Pnonlinear < 0.001). According to subgroup analyses, these relationships were more significant in males, or >45 years old (Ptrend < 0.05). Nevertheless, no significant relationship was found between dietary-derived CoQ10 intake and WBC. Conclusions: These findings suggested a significant negative association between dietary-derived CoQ10 and hsCRP levels.

Associations between the inflammatory potential of diets with adherence to plant-based dietary patterns and the risk of new-onset cardiometabolic diseases in Chinese adults: findings from a nation-wide prospective cohort study

Aims: convincing evidence is still limited for the validation of associations between the inflammatory potential of diets, based on the dietary inflammatory index (DII), and cardiometabolic outcomes. We aimed to investigate the associations between the DII with adherence to plant-based dietary patterns and the risk of new-onset cardiometabolic diseases (CMDs), including stroke, type 2 diabetes mellitus (T2DM) and myocardial infarction (MI). Methods: adults (N = 14 652) from the China Health and Nutrition Survey (1997-2015) were included in the current analysis. Dietary intake data were collected using a combination of 3 day consecutive 24 h dietary recalls and the food weighing method. The DII was calculated with established and validated methods. CMDs were identified using validated self-reported questionnaires. The Cox proportional hazard regression model was used for statistical analysis. Results: during a mean follow-up of 10 years, a total of 404 new-onset stroke, 1051 new-onset T2DM and 280 new-onset MI cases were identified. Lower PDI, hPDI, ERD, WISH and PHDI scores and higher uPDI scores were associated with higher DII scores (all P-trend < 0. 0001). A pro-inflammatory diet, as reflected by relatively higher DII scores, was positively associated with an increased risk of stroke (Q5 vs. Q1: HR = 1.90; 95% CI: 1.26-2.88; P-trend = 0.0006), T2DM (Q5 vs. Q1: HR = 2.08; 95% CI: 1.61-2.69; P-trend < 0.0001) and MI (Q5 vs. Q1: HR = 1.70; 95% CI: 1.04-2.76; P-trend = 0.0114) in the entire cohort. Sex and BMI significantly modified the association between the DII and the risk of T2DM, and sex significantly modified the association between the DII and the risk of MI. Conclusions: lower adherence to healthy and sustainable plant-based dietary patterns and higher adherence to unhealthy plant-based dietary patterns were associated with higher DII scores. With the use of the DII, we reported long-term positive associations between a pro-inflammatory diet and an increased risk of new-onset stroke, T2DM and MI in Chinese adults who were free from CMDs and cancer at the baseline. These findings provided evidence for the validation of associations between the DII and cardiometabolic health, and contributed to the current literature suggesting careful evaluations of whether the DII should be incorporated into dietary guidelines and utilized as an effective tool for improving the diet quality and CMD prevention in the Chinese population.

The Link between Trace Metal Elements and Glucose Metabolism: Evidence from Zinc, Copper, Iron, and Manganese-Mediated Metabolic Regulation

Trace metal elements are of vital importance for fundamental biological processes. They function in various metabolic pathways after the long evolution of living organisms. Glucose is considered to be one of the main sources of biological energy that supports biological activities, and its metabolism is tightly regulated by trace metal elements such as iron, zinc, copper, and manganese. However, there is still a lack of understanding of the regulation of glucose metabolism by trace metal elements. In particular, the underlying mechanism of action remains to be elucidated. In this review, we summarize the current concepts and progress linking trace metal elements and glucose metabolism, particularly for the trace metal elements zinc, copper, manganese, and iron.

Spotlight on iron and ferroptosis: research progress in diabetic retinopathy

Iron, as the most abundant metallic element within the human organism, is an indispensable ion for sustaining life and assumes a pivotal role in governing glucose and lipid metabolism, along with orchestrating inflammatory responses. The presence of diabetes mellitus (DM) can induce aberrant iron accumulation within the corporeal system. Consequentially, iron overload precipitates a sequence of important adversities, subsequently setting in motion a domino effect wherein ferroptosis emerges as the utmost pernicious outcome. Ferroptosis, an emerging variant of non-apoptotic regulated cell death, operates independently of caspases and GSDMD. It distinguishes itself from alternative forms of controlled cell death through distinctive morphological and biochemical attributes. Its principal hallmark resides in the pathological accrual of intracellular iron and the concomitant generation of iron-driven lipid peroxides. Diabetic retinopathy (DR), established as the predominant cause of adult blindness, wields profound influence over the well-being and psychosocial strain experienced by afflicted individuals. Presently, an abundance of research endeavors has ascertained the pervasive engagement of iron and ferroptosis in the microangiopathy inherent to DR. Evidently, judicious management of iron overload and ferroptosis in the early stages of DR bears the potential to considerably decelerate disease progression. Within this discourse, we undertake a comprehensive exploration of the regulatory mechanisms governing iron homeostasis and ferroptosis. Furthermore, we expound upon the subsequent detriments induced by their dysregulation. Concurrently, we elucidate the intricate interplay linking iron overload, ferroptosis, and DR. Delving deeper, we engage in a comprehensive deliberation regarding strategies to modulate their influence, thereby effecting prospective interventions in the trajectory of DR's advancement or employing them as therapeutic modalities.

Association Between the Dietary Inflammatory Index and the Risk of Fracture in Chinese Adults: Longitudinal Study

BACKGROUND

Chronic inflammation plays a crucial role in tissue injury, osteoporosis, and fracture. The dietary inflammatory index (DII) is a tool for assessing the potential for inflammation in the diet. However, the association between the DII and fractures remains controversial from previous studies.

OBJECTIVE

We aimed to explore the correlation between the DII and fracture risk in Chinese adults.

METHODS

We included 11,999 adults (5519 men and 6480 women) who were a part of the China Health and Nutrition Survey (1997-2015) prospective cohort. A 3-day, 24-hour meal review method was used to calculate the DII score. The fractures were identified using a questionnaire. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and 95% CIs for fractures. Subgroup, sensitivity, and restricted cubic spline analyses were performed.

RESULTS

During the 18 years of follow-up (median follow-up 9.0 years), 463 men and 439 women developed fractures. The median DII score was 0.64 (IQR -1.74 to 1.46) for the total sample, 0.75 (IQR -1.68 to 1.50) for men, and 0.53 (IQR -1.79 to 1.42) for women. The DII score had a positive correlation with the risk of fracture among women but not among men. For men, after adjusting for covariates, the HRs for quintiles of DII were 1, 0.96 (95% CI 0.66-1.41), 1.05 (95% CI 0.74-1.49), 0.89 (95% CI 0.62-1.26), and 0.94 (95% CI 0.67-1.34; trend: P=.62). The HRs for women were 1, 1.13 (95% CI 0.72-1.79), 1.24 (95% CI 0.83-1.86), 1.51 (95% CI 1.02-2.22), and 1.62 (95% CI 1.10-2.39; trend: P=.004). The restricted cubic spline analysis showed a significant association between fracture risk and DII score in women (overall association: P=.01); as the DII scores were >0.53, HRs showed a significant upward trend. Women aged <50 years or who are nonsmokers, who are nondrinkers, or with nonabdominal obesity had a positive association between fracture risk and the DII score. In sensitivity analyses, after excluding people with diabetes or hypertension, there was still a positive association between fracture risk and the DII score in women. Among the DII components, the DII scores of protein (trend: P=.03), niacin (trend: P=.002), and iron (trend: P=.02) showed significant associations with the risk of fracture in women.

CONCLUSIONS

Proinflammatory diet consumption increased the fracture risk in Chinese women aged <50 years. The high consumption of anti-inflammatory foods and low consumption of proinflammatory foods may be an important strategy to prevent fractures in women.

Exposure to multiple metals in adults and diabetes mellitus: a cross-sectional analysis

Diabetes mellitus (DM) is the most widely recognized metabolic illness with expanding morbidity among ongoing years. Its high incapacity rate and death rate badly affect individuals' quality of life. Increasing proofs backed the relationship between metal exposures with the risk of DM, but the methodological boundedness cannot clarify the complexity of the internal relationship of metal mixtures. We fitted the logistic regression model, weighted quantile sum regression model, and Bayesian kernel machine regression model to assess the relationship between the metal exposures with DM in adults who participated in the National Health and Nutrition Examination Survey 2013-2016. The metals (lead, cadmium, and copper) levels were significantly higher among diabetic compared to the healthy controls. In the logistic regression model established for each single metal, lead and manganese were associated with DM in both unadjusted and mutually adjusted models (highest vs. lowest concentration quartile). When considering all metal as a mixed exposure, we found a generally positive correlation between metal mixtures with DM (binary outcome) and glycohemoglobin (HbA1c) levels (continuous outcome). Exposure to metal mixtures was associated with an increased risk of DM and elevated levels of HbA1c.

Association of Body Iron Metabolism with Type 2 Diabetes Mellitus in Chinese Women of Childbearing Age: Results from the China Adult Chronic Disease and Nutrition Surveillance (2015)

High iron stores have been reported to be associated with type 2 diabetes mellitus (T2DM). However, evidence for the associations of iron metabolism with T2DM is inconsistent, and whether there is a threshold effect remains controversial. In the present study, we aimed to examine the associations between various iron biomarkers and the risk of T2DM as well as impaired glucose metabolism (IGM) and hyperglycemia in Chinese women of childbearing age. A total of 1145 women were divided into three groups (normal blood glucose metabolism group; IGM group; T2DM group). Biomarkers of iron metabolism (serum ferritin (SF), transferrin, soluble transferrin receptor (sTfR), transferrin saturation, serum iron, total body iron, and sTfR-to-lgferritin index) were measured. After adjusting for various confounding risk factors, SF and sTfR were positively associated with the risk of IGM (fourth vs. first quartile: SF odds ratio (OR) = 1.93 (95% CI 1.17-3.20) and sTfR OR = 3.08 (95% CI 1.84-5.14)) and T2DM (SF OR = 2.39 (95% CI 1.40-4.06) and sTfR OR = 3.84 (95% CI 2.53-5.83)). There was a nonlinear relationship between SF and risk of T2DM and hyperglycemia (p for nonlinearity < 0.01). Our findings suggested that SF and sTfR could be independent predictors of T2DM risk.

Long-Term Visit-To-Visit Blood Pressure Variability and Risk of Diabetes Mellitus in Chinese Population: A Retrospective Population-Based Study

Objectives: To examine the association between visit-to-visit blood pressure variability (BPV) and incident diabetes mellitus (DM) risk in a Chinese population. Methods: Data comes from China Health and Nutrition Survey (n = 15,084). BPV was estimated as the average real variability (ARV) using at least three BP measurements from the year preceding the event and was divided into quartiles. Participants were also categorized into 9 groups on the basis of combinations of systolic BPV (SBPV) and diastolic BPV (DBPV) tertiles. Cox proportional hazards regression models were used. Results: During a median follow-up of 16.8 years, 1,030 (6.8%) participants developed diabetes (incidence rate: 4.65/1,000 person-years). The HRs (95% CIs) for the highest quartile (vs. the lowest quartile) of SBPV and DBPV were 1.60 (1.30-1.97) and 1.37 (1.13-1.67), respectively. Participants with both highest SBPV and DBPV tertile had an ≈89% higher risk of DM (HR, 1.89; 95% CI, 1.47-2.42) compared with those in the both SBPV and DBPV tertile 1 group. Conclusion: Higher SBP ARV and DBP ARV were independently associated with increased risk of incident DM, which was augmented when both presented together.

Associations between Conventional and Emerging Indicators of Dietary Carbohydrate Quality and New-Onset Type 2 Diabetes Mellitus in Chinese Adults

Dietary glycemic index (GI), carbohydrate to fiber ratio (CF) and carbohydrate quality index (CQI) are conventional and emerging indicators for carbohydrate quality. We aimed to investigate the associations between these indicators and new-onset type 2 diabetes mellitus (T2DM) risk among Chinese adults. This prospective cohort study included 14,590 adults from the China Health and Nutrition Survey without cardiometabolic diseases at baseline. The associations between dietary GI, CF and CQI and T2DM risk were assessed using Cox proportional hazard regression analysis and dose-response relationships were explored using restricted cubic spline and threshold analysis. After a mean follow-up duration of 10 years, a total of 1053 new-onset T2DM cases occurred. There were U-shaped associations between dietary GI and CF and T2DM risk (both P-nonlinear < 0.0001), and T2DM risk was lowest when dietary GI was 72.85 (71.40, 74.05) and CF was 20.55 (17.92, 21.91), respectively (both P-log likelihood ratio < 0.0001). Inverse associations between CQI and T2DM risk specifically existed in participants < 60 y or attended middle school or above (both P-trend < 0.05). These findings indicated that moderate dietary GI and CF range and a higher dietary CQI score may be suggested for T2DM prevention in Chinese adults.

The Association between Methionine Intake and Diabetes in Chinese Adults-Results from the China Health and Nutrition Survey

This study aimed to evaluate the association between methionine intake and diabetes prevalence in Chinese adults and explore whether the association was source-specific. Data from 12,849 adults aged ≥20 years old were used from the China Health and Nutrition Survey during 1997-2011. Diabetes was diagnosed as self-reported and/or when blood tests results met the diagnostic criteria. A 3-day, 24-h recall was used to assess different sources of methionine. Multivariable mixed linear regression was used to examine the associations. Across the quartiles of total methionine intake, the odds ratio (ORs, 95% CI) of diabetes were 1.00, 1.49 (1.21 to 1.82), 1.72 (1.37 to 2.15), and 2.53 (1.97 to 3.23). In the subgroup analysis, similar trends were observed in both animal and plant methionine. There was a significant interaction between urbanization and diabetes. The positive association was only significant in those who lived in low or medium urbanization areas. The ORs (95% CI) were 1.00, 1.27 (0.85 to 1.88), 1.56 (1.01 to 2.39), and 1.79 (1.09 to 2.95) for medium urbanization, respectively. No interaction was identified when stratified by different methionine sources. In conclusion, methionine intake was positively associated with diabetes independent of food source, and it was modified by urbanization levels.

Variety and Quantity of Dietary-Insoluble Fiber Intake From Different Sources and Risk of New-Onset Diabetes

CONTEXT

The relationship between the variety and quantity of different sources of dietary-insoluble fiber intake and diabetes remain uncertain.

OBJECTIVE

We aimed to investigate the associations between the variety and quantity of insoluble fiber intake from 6 major food sources and new-onset diabetes, using data from the China Health and Nutrition Survey (CHNS).

METHODS

A total of 16 272 participants without diabetes at baseline from CHNS were included. Dietary intake was measured by 3 consecutive 24-hour dietary recalls combined with a household food inventory. Energy-adjusted dietary intake was used in analyses. The variety score of insoluble-fiber sources was defined as the number of specific-sourced insoluble fiber consumed at the appropriate level, accounting for both types and quantity of insoluble fiber. Participants with self-reported physician-diagnosed diabetes, or fasting glucose greater than or equal to 7.0 mmol/L or glycated hemoglobin A1c greater than or equal to 6.5% during follow-up were defined as having new-onset diabetes.

RESULTS

During a median follow-up of 9.0 years, 1101 participants developed new-onset diabetes. There were U-shaped associations for energy-adjusted dietary intake of total insoluble fiber, and energy-adjusted insoluble fiber derived from refined and whole grains; and L-shaped associations for energy-adjusted insoluble fiber derived from vegetables, legumes, fruits, and tubers with new-onset diabetes (all P for nonlinearity < .001). Moreover, a higher variety score of insoluble fiber sources was significantly associated with a lower risk of new-onset diabetes (per 1-score increment, hazard ratio, 0.61; 95% CI, 0.58-0.65).

CONCLUSION

There was an inverse association between the variety of insoluble fiber with appropriate quantity from different food sources and new-onset diabetes.

The Effect of Dietary Protein Intake on the Risk of Gestational Diabetes

Background. The results of epidemiological studies on the association between dietary protein intake and gestational diabetes mellitus (GDM) are controversial. Thus, this systematic review and meta-analysis of cohort studies were established to attain comprehensive findings regarding the association between dietary protein and the risk of GDM. Methods. Bibliographic databases including PubMed, Scopus, Web of Science, and Google Scholar were searched to discover papers related to dietary protein and the risk of GDM. The summary relative risks with 95% confidence intervals (CIs) were estimated through a random effect model for the analysis of the highest versus the lowest categories of dietary proteins. Results. A significantly increased risk of GDM among women who consumed the highest amount of animal protein was observed (summarized risk estimate: 1.52; 95% CI: 1.07, 2.17; I2 = 50.8%). No significant associations were identified regarding vegetable protein (summarized risk estimate:0.99, 95% CI: 0.80 to 1.23, I2 = 63.8%) and total protein (summarized risk estimate: 1.12; 95% CI: 0.88, 1.41; I2 = 35.4%). Conclusion. This review revealed that total protein intake had no relationship with the risk of GDM, while animal protein increases this risk. Further larger prospective cohort studies are required to confirm our results.

Establishment of dynamic nomogram and risk score models for T2DM: a retrospective cohort study in Beijing

BACKGROUND

Health interventions can delay or prevent the occurrence and development of diabetes. Dynamic nomogram and risk score (RS) models were developed to predict the probability of developing type 2 diabetes mellitus (T2DM) and identify high-risk groups.

METHODS

Participants (n = 44,852) from the Beijing Physical Examination Center were followed up for 11 years (2006-2017); the mean follow-up time was 4.06 ± 2.09 years. Multivariable Cox regression was conducted in the training cohort to identify risk factors associated with T2DM and develop dynamic nomogram and RS models using weighted estimators corresponding to each covariate derived from the fitted Cox regression coefficients and variance estimates, and then undergone internal validation and sensitivity analysis. The concordance index (C-index) was used to assess the accuracy and reliability of the model.

RESULTS

Of the 44,852 individuals at baseline, 2,912 were diagnosed with T2DM during the follow-up period, and the incidence density rate per 1,000 person-years was 16.00. Multivariate analysis indicated that male sex (P < 0.001), older age (P < 0.001), high body mass index (BMI, P < 0.05), high fasting plasma glucose (FPG, P < 0.001), hypertension (P = 0.015), dyslipidaemia (P < 0.001), and low serum creatinine (sCr, P < 0.05) at presentation were risk factors for T2DM. The dynamic nomogram achieved a high C-index of 0.909 in the training set and 0.905 in the validation set. A tenfold cross-validation estimated the area under the curve of the nomogram at 0.909 (95% confidence interval 0.897-0.920). Moreover, the dynamic nomogram and RS model exhibited acceptable discrimination and clinical usefulness in subgroup and sensitivity analyses.

CONCLUSIONS

The T2DM dynamic nomogram and RS models offer clinicians and others who conduct physical examinations, respectively, simple-to-use tools to assess the risk of developing T2DM in the urban Chinese current or retired employees.

Overall lifestyles and socioeconomic inequity in mortality and life expectancy in China: the China health and nutrition survey

BACKGROUND

socioeconomic inequity in mortality and life expectancy remains inconclusive in low- and middle-income countries, and to what extent the associations are mediated or modified by lifestyles remains debatable.

METHODS

we included 21,133 adults from China Health and Nutrition Survey (1991-2011) and constructed three parameters to reflect participants' overall individual- (synthesising income, education and occupation) and area-level (urbanisation index) socioeconomic status (SES) and lifestyles (counting the number of smoking, physical inactivity and unhealthy diet and bodyweight). HRs for mortality and life expectancy were estimated by time-dependent Cox model and life table method, respectively.

RESULTS

during a median follow-up of 15.2 years, 1,352 deaths were recorded. HRs (95% CIs) for mortality comparing low versus high individual- and area-level SES were 2.38 (1.75-3.24) and 1.84 (1.51-2.24), respectively, corresponding to 5.7 (2.7-8.6) and 5.0 (3.6-6.3) life-year lost at age 50. Lifestyles explained ≤11.5% of socioeconomic disparity in mortality. Higher lifestyle risk scores were associated with higher mortality across all socioeconomic groups. HR (95% CI) for mortality comparing adults with low individual-level SES and 3-4 lifestyle risk factors versus those with high SES and 0-1 lifestyle risk factors was 7.06 (3.47-14.36), corresponding to 19.1 (2.6-35.7) life-year lost at age 50.

CONCLUSION

this is the first nationwide cohort study reporting that disadvantaged SES was associated with higher mortality and shorter life expectancy in China, which was slightly mediated by lifestyles. Risk lifestyles were related to higher mortality across all socioeconomic groups, and those with risk lifestyles and disadvantaged SES had much higher mortality risks.

Dietary Copper and Selenium Intakes and the Risk of Type 2 Diabetes Mellitus: Findings from the China Health and Nutrition Survey

The long-term associations between dietary copper (Cu) and selenium (Se) intakes and type 2 diabetes mellitus (T2DM) risk are unclear. We aimed to examine the prospective associations between dietary Cu and Se intakes and T2DM risk in Chinese adults. A total of 14,711 adults from the China Health and Nutrition Survey (1997–2015) were included. Nutrient intakes were assessed by 3 consecutive 24 h recalls and food-weighing methods. T2DM was identified by a validated questionnaire and laboratory examination. Cox regression models were used for statistical analysis. A total of 1040 T2DM cases were diagnosed during 147,142 person-years of follow-up. In fully adjusted models, dietary Cu or Se intake was not associated with T2DM risk. Dietary Se intake significantly modified the association between dietary Cu intake and T2DM risk, and dietary Cu intake was positively associated with T2DM risk when Se intake was lower than the median (p-interaction = 0.0292). There were no significant effect modifications on the associations by age, sex, BMI, or region. Although dietary Cu or Se intake was not independently associated with T2DM risk in Chinese adults free from cardiometabolic diseases and cancer at the baseline, there was a significant interaction between dietary Cu and Se intakes on T2DM risk.

Abdominal volume index trajectories and risk of diabetes mellitus: Results from the China Health and Nutrition Survey

AIMS/INTRODUCTION

Abdominal obesity is a risk factor for developing diabetes mellitus, but trajectories of abdominal obesity over time and incident diabetes mellitus have not been considered. We derived trajectories of abdominal volume index (AVI) over 16 years of follow up, and examined the associations between AVI trajectories and risk of diabetes mellitus.

MATERIALS AND METHODS

Data were used from the China Health and Nutrition Survey, and 5,267 participants were enrolled to fit the trajectory of AVI by using latent class growth models. Multivariate logistic regression models explored the relationship between different AVI trajectories and risk of diabetes mellitus. In addition, we examined the slope of the AVI trajectories in relation to age to identify appropriate life course intervention opportunities for the prevention of diabetes mellitus.

RESULTS

Three trajectories were derived reflecting graded categories in the speed and slope of increase in AVI over time: slow, intermediate and fast increase group, respectively. After multivariate adjustment, the odds ratios for diabetes mellitus among those in the intermediate and fast increase groups were 1.81 (95% confidence interval 1.37-2.38, P < 0.001) and 2.80 (95% confidence interval 1.85-4.24, P < 0.001) respectively, relative to the slow increase group. The distribution of AVI slope in the slow increase group showed an inverted "U" shape, whereas the fast increase group presented a "U" shape.

CONCLUSIONS

AVI trajectory is associated with an increased risk of diabetes mellitus. These results provide new insights on the relationship between abdominal adiposity and diabetes mellitus, which in turn can help improve clinical and public health intervention for diabetes mellitus prevention.

Iron Overload and the Risk of Diabetes in the General Population: Results of the Chinese Health and Nutrition Survey Cohort Study

BACKGROUND

Recent studies have found that there are significant associations between body iron status and the development of diabetes. In the present study, we aimed to analyze the association among iron overload (IO), insulin resistance (IR), and diabetes in Chinese adults, and to explore the sex difference.

METHODS

Men and women (age >19 years) who participated in the Chinese Health and Nutrition Survey and did not have diabetes at baseline were followed between 2009 and 2015 (n=5,779). Over a mean of 6 years, 75 participants were diagnosed with incident diabetes. Logistic regression was used to assess the risk factors associated with IO. Cox proportional hazard regression was used to estimate the risk of incident diabetes and to determine whether the risk differed among subgroups. Causal mediation analysis (CMA) was used to explore the mechanism linking IO and diabetes.

RESULTS

According to sex-stratified multivariable-adjusted Cox proportional hazards regression, IO increased the risk of incident diabetes. Women with IO had a higher risk of diabetes than men. Subgroup analysis with respect to age showed that the association between IO and diabetes was stronger in older women and younger men (P<0.001). CMA showed that liver injury (alanine transaminase) and lipid metabolism abnormalities (triglyceride, apolipoprotein B) contributed to the association between IO and diabetes.

CONCLUSION

IO is associated with diabetes and this association is sex-specific. IO may indirectly induce IR via liver injury and lipid metabolism abnormalities, resulting in diabetes.

Dietary iron intake and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of prospective cohort studies

PURPOSE

We aimed to assess the long-term association of total, heme, non-heme, and supplemental iron intake and risk of type 2 diabetes (T2D).

METHODS

PubMed, Scopus, and Web of Science were searched to October 2021. Two researchers extracted data in duplicate and rated the certainty in the estimates using the GRADE approach. Random-effects models were applied to estimate the relative risks (RRs) and 95% CIs. Dose-response associations were modeled by a one-stage weighted mixed-effects meta-analysis.

RESULTS

Eleven prospective cohort studies 323,788 participants and 28,837 incident cases of T2D were included. High versus low category meta-analysis indicated that higher heme iron intake was associated with a 20% higher risk of T2D (95% CI 1.07, 1.35; I² = 77%, n = 11; GRADE = moderate). Dose-response analysis indicated a positive monotonic association, wherein each 1 mg/day increment in heme iron intake was related to a 16% higher risk (95% CI 1.03, 1.30). No significant relationship was detected between dietary intakes of total, non-heme, and supplemental iron and risk of T2D (GRADE = very low).

CONCLUSIONS

In summary, higher heme iron intake was associated with a higher risk of T2D. Our results are in line with existing evidence indicating that adopting a Western-style dietary pattern, rich in dietary sources of heme iron, was associated with a higher risk of T2D.

REGISTRY AND REGISTRY NUMBER

The protocol of this systematic review was registered at PROSPERO (registration number: CRD42021226835).

U-shaped Association Between Dietary Zinc Intake and New-onset Diabetes: A Nationwide Cohort Study in China

AIMS

We aimed to investigate the relationship of dietary zinc intake with new-onset diabetes among Chinese adults.

MATERIALS AND METHODS

A total of 16 257 participants who were free of diabetes at baseline from the China Health and Nutrition Survey were included. Dietary intake was measured by 3 consecutive 24-hour dietary recalls combined with a household food inventory. Participants with self-reported physician-diagnosed diabetes, or fasting glucose ≥ 7.0 mmol/L, or glycated hemoglobin ≥ 6.5% during the follow-up were defined as having new-onset diabetes.

RESULTS

A total of 1097 participants developed new-onset diabetes during a median follow-up duration of 9.0 years. Overall, the association between dietary zinc intake and new-onset diabetes followed a U-shape (P for nonlinearity < 0.001). The risk of new-onset diabetes was significantly lower in participants with zinc intake < 9.1 mg/day (per mg/day: hazard ratio [HR], 0.73; 95% CI, 0.60-0.88), and higher in those with zinc intake ≥ 9.1 mg/day (per mg/day: HR, 1.10; 95% CI, 1.07-1.13). Consistently, when dietary zinc intake was assessed as deciles, compared with those in deciles 2-8 (8.9 -<12.2 mg/day), the risk of new-onset diabetes was higher for decile 1 (<8.9 mg/day: HR, 1.29; 95% CI, 1.04-1.62), and deciles 9 to 10 (≥12.2 mg/day: HR, 1.62; 95% CI, 1.38-1.90). Similar U-shaped relations were found for plant-derived or animal-derived zinc intake with new-onset diabetes (all P for nonlinearity < 0.001).

CONCLUSIONS

There was a U-shaped association between dietary zinc intake and new-onset diabetes in general Chinese adults, with an inflection point at about 9.1 mg/day.

Life-course blood pressure trajectories and incident diabetes: A longitudinal cohort in a Chinese population

BACKGROUND

Blood pressure levels are correlated with diabetes among middle-aged or older adults. However, longitudinal trajectories of blood pressure during young adulthood and their impact on diabetes have been insufficiently studied.

METHODS

The longitudinal cohort consisted of 4,625 adults who had blood pressure and body mass index (BMI) repeatedly measured five to nine times during 18-60 years of age. Distinct systolic blood pressure (SBP) trajectories were identified by a group-based trajectory model. Logistic regression analyses were used to investigate the association between trajectory patterns or quartiles of area under the curve values of SBP trajectories and incident diabetes, respectively.

RESULTS

Four distinct trajectory groups were identified for SBP: normotensive-stable (n = 761, 16.5%), prehypertension-stable (n = 2,381, 51.5%), stage I hypertension-increasing (n = 1,231, 26.6%), and stage II hypertension-increasing (n = 251, 5.4%). Compared with subjects who remained at SBP <120 mmHg in the normotensive-stable group, individuals in the prehypertension-stable trajectory exhibited a normal SBP range (<140 mmHg), and they still had a significantly higher risk of diabetes (adjusted OR = 1.82, p = 0.029). Individuals had a greater risk of diabetes in the stage I hypertension-increasing group (adjusted OR = 2.31, p = 0.006) and the highest risk in the stage II hypertension-increasing group (adjusted OR = 3.91, p < 0.001) relative to the normotensive-stable group. Furthermore, compared with the first quartile, adjusted ORs (95% CIs) of the fourth quartile of SBP incremental and total AUC were 2.50 (1.61-3.97) and 1.82 (1.15-2.94), respectively.

CONCLUSIONS

Long-term SBP trajectory is a significant predictor for incident diabetes, which is independent of baseline SBP and body weight, attaching importance to maintaining optimal blood pressure levels and controlling changing slopes of SBP for preventing diabetes.

Long-term trajectories of BMI and cumulative incident metabolic syndrome: A cohort study

BACKGROUND

Body mass index (BMI) has been widely recognized as a risk factor for metabolic syndrome (MetS). However, the relationship between the trajectory of BMI and cumulative incident MetS is still unclear. We investigate the associations of long-term measurements of BMI with MetS among young adults in the China Health and Nutrition Survey.

METHODS

We enrolled individuals aged 10 to 20 at baseline with recorded BMI at each follow-up interview, and 554 participants were finally included in our study. The assessment and incidence of MetS were evaluated by blood tests and physical examinations in their adulthood. A latent class growth mixed model was used to identify three BMI trajectory patterns: a low baseline BMI with slow development (low-slow, n=438), a low baseline BMI with fast development (low-fast, n=66), and a high baseline BMI with fast development (high-fast, n=50). Logistic regression was used to explore the relationship between different BMI trajectories and the incidence of MetS.

RESULT

During a follow-up of 16 years, 61 (11.01%) participants developed MetS. The combination of elevated triglycerides and reduced high-density lipoprotein cholesterol was most frequent in diagnosed MetS. In multivariate adjusted models, the low-fast and high-fast BMI trajectories showed a significantly higher risk of MetS than those with the low-slow BMI trajectory (low-high: OR = 3.40, 95% CI: 1.14-10.13, P < 0.05; high-fast: OR = 5.81, 95% CI: 1.63-20.69, P < 0.05).

CONCLUSION

Our study identified three BMI trajectories in young adults and found that long-term measurements of BMI were also associated with cumulative incident MetS.

Antipsychotic-Related Risks of Type 2 Diabetes Mellitus in Enrollees With Schizophrenia in the National Basic Public Health Service Program in Hunan Province, China

BACKGROUND

Antipsychotics contribute to the development of type 2 diabetes mellitus (T2DM) in individuals with schizophrenia. However, the extent of the relationship between antipsychotic use and T2DM varies in different settings, and the magnitude of the drug-specific effects fluctuates widely. This study aimed to explore the association of T2DM with antipsychotic use among enrollees with schizophrenia in China's National Basic Public Health Service Program (NBPHSP) and the drug-specific relationship with T2DM among patients receiving antipsychotic monotherapy.

METHODS

We recruited diabetes-free patients with schizophrenia who were enrolled in the NBPHSP of Hunan Province from October 2009 to December 2018. The participants were classified into the following three groups: regular antipsychotic use, intermittent antipsychotic use, and antipsychotic-free groups. The patients were followed up until they received a T2DM diagnosis or until April 2019. Cox regression models were constructed to calculate the overall and drug-specific hazard ratios (HRs) to determine the antipsychotic-T2DM relationship. Interactive and subgroup analyses were performed to assess the heterogeneity of the effects across subgroups.

RESULTS

A total of 122,064 NBPHSP enrollees with schizophrenia were followed up for 1,507,829 cumulative person-years, and 2,313 (1.89%) patients developed T2DM. Patients who regularly and intermittently used antipsychotics had 117% (HR: 2.17, 95% CI: 1.83-2.57) and 53% (HR: 1.53, 95% CI: 1.23-1.90) higher risks of developing T2DM than antipsychotic-free patients, respectively. Regarding monotherapy, the T2DM risk increased by 66, 80, 62, and 64% after the regular use of clozapine, risperidone, chlorpromazine, and perphenazine, respectively. In addition, the antipsychotic-related risk of T2DM decreased as the patient's baseline body mass index, and baseline fasting plasma glucose level, as well as the dietary proportion of animal products, increased.

CONCLUSION

Antipsychotics, especially clozapine, risperidone, chlorpromazine, and perphenazine, increased the T2DM risk among NBPHSP enrollees with schizophrenia. Mental health officers should accurately identify enrollees at a high risk of T2DM and take appropriate preventive measures to reduce the incidence of T2DM among patients with schizophrenia.

Dietary iron intake and the risk of type 2 diabetes mellitus in middle-aged and older adults in urban China: a prospective cohort study

The association between dietary Fe intake and diabetes risk remains inconsistent. We aimed to explore the association between dietary Fe intake and type 2 diabetes mellitus (T2DM) risk in middle-aged and older adults in urban China. This study used data from the Guangzhou Nutrition and Health Study, an on-going community-based prospective cohort study. Participants were recruited from 2008 to 2013 in Guangzhou community. A total of 2696 participants aged 40-75 years without T2DM at baseline were included in data analyses, with a median of 5·6 (interquartile range 4·1-5·9) years of follow-up. T2DM was identified by self-reported diagnosis, fasting glucose ≥ 7·0 mmol/l or glycosylated Hb ≥ 6·5 %. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95 % CI. We ascertained 205 incident T2DM cases during 13 476 person-years. The adjusted HR for T2DM risk in the fourth quartile of haem Fe intake was 1·92 (95 % CI 1·07, 3·46; Ptrend = 0·010), compared with the first quartile intake. These significant associations were found in haem Fe intake from total meat (HR 2·74; 95 % CI 1·22, 6·15; Ptrend = 0·011) and haem Fe intake from red meat (HR 1·86; 95 % CI 1·01, 3·44; Ptrend = 0·034), but not haem Fe intake from processed meat, poultry or fish/shellfish. The association between dietary intake of total Fe or non-haem Fe with T2DM risk had no significance. Our findings suggested that higher dietary intake of haem Fe (especially from red meat), but not total Fe or non-haem Fe, was associated with greater T2DM risk in middle-aged and older adults.

Dietary carbohydrate intake and new-onset diabetes: A nationwide cohort study in China

AIM

The association of carbohydrate intake with diabetes risk remains uncertain. We aimed to evaluate the prospective associations of the amount and types of carbohydrate intake with new-onset diabetes.

METHODS

A total of 16,260 non-diabetic participants from the China Health and Nutrition Survey (CHNS) were included. Dietary intake was collected by three consecutive 24-h dietary recalls combined with a household food inventory. Participants with self-reported physician diagnosed diabetes, or fasting plasma glucose ≥7.0 mmol/L or glycated hemoglobin ≥6.5% during the follow-up were defined having new-onset diabetes.

RESULTS

During a median follow-up of 9 years (158,930 person-years), 1100 participants developed diabetes. Overall, there was a U-shaped association between percent of energy from carbohydrate intake and new-onset diabetes, with minimal risk at 49-56% of energy from total carbohydrate intake (quartile 2) (P for nonlinearity <0.001). Moreover, there was an L-shaped association between high-quality carbohydrate intake and new-onset diabetes (P for nonlinearity <0.001), and a J-shaped association of low-quality carbohydrate intake with new-onset diabetes (P for nonlinearity <0.001). Furthermore, there was an inverse association between the plant-based low-carbohydrate diet scores for low-quality carbohydrate and new-onset diabetes. However, a reversed J-shaped association was found between the animal-based low-carbohydrate diet scores for low-quality carbohydrate and new-onset diabetes (P for nonlinearity <0.001).

CONCLUSIONS

There was a U-shape association between percent of total carbohydrate intake and new-onset diabetes, with the lowest risk at 49-56% carbohydrate intake. Our findings provide some evidence for the intake of high-quality carbohydrate, and the substitution of plant-based products for low-quality carbohydrate for primary prevention of diabetes.

Association between maternal plasma ferritin concentration, iron supplement use, and the risk of gestational diabetes: a prospective cohort study

BACKGROUND

The association between iron supplementation and gestational diabetes mellitus (GDM) is still inconclusive, and this association has not been extensively studied in relation to plasma ferritin in the early second trimester.

OBJECTIVES

We aimed to prospectively examine the independent and combined associations of plasma ferritin concentrations and iron supplement use with GDM.

METHODS

We studied 2117 women from the Tongji Maternal and Child Health Cohort in Wuhan, China. Plasma ferritin around 16 weeks' gestation was measured by ELISA kits and information on iron supplement use was collected by questionnaires. GDM was diagnosed by a 75-g oral-glucose-tolerance test (OGTT) at 24-28 weeks' gestation. A log-Poisson regression model was used to estimate the RR of GDM associated with plasma ferritin and iron supplementation.

RESULTS

The median and IQR of plasma ferritin was 52.1 (29.6-89.9) ng/mL, and 863 (40.8%) participants reported use of iron supplements during the second trimester. A total of 219 (10.3%) participants developed GDM. Adjusted RRs (95% CIs) for GDM across increasing quartiles of plasma ferritin were 1.00 (reference), 2.14 (1.37, 3.34), 2.03 (1.30, 3.19), and 2.72 (1.76, 4.21), respectively. After adjustment, supplemental iron ≥60 mg/d during the second trimester was associated with an increased risk of GDM compared with nonusers (RR: 1.37; 95% CI: 1.02, 1.84).

CONCLUSIONS

Both elevated plasma ferritin concentrations in the early second trimester and use of ≥60 mg/d of supplemental iron during pregnancy are independently associated with increased risk of GDM. Further clinical trials with precision nutrition approaches considering both baseline iron status and supplement use are needed to evaluate the benefits and risks of iron supplementation during pregnancy.

Associations between serum amino acids and incident type 2 diabetes in Chinese rural adults

BACKGROUND AND AIMS

Some amino acids (AAs) may be associated with type 2 diabetes (T2DM). This study aimed to determine the associations of individual AAs with the development of T2DM in rural Chinese adults.

METHODS AND RESULTS

A cohort study of 1199 individuals aged 18 years or older was conducted from 2006 to 2008 in a rural community of Deqing, China, a repeated survey was done in 2015 and data linkage with the electronic health records system was performed each year for identifying new T2DM cases. A high-performance liquid chromatography approach was used to measure the baseline serum concentrations of 15 AAs. Cox proportional hazards models were used to examine the associations between AAs and the risk of incident T2DM. A total of 98 new T2DM cases were identified during the follow-up of 12 years on average. Among 15 AAs, proline was associated with an increased risk of incident T2DM after adjusted for age, sex, body mass index, fasting plasma glucose, family history of T2DM, smoking status, alcohol use, and history of hypertension, the adjusted hazard ratio for 1-standard deviation increment was 1.20 (95% confidence interval: 1.00, 1.43). The association tended to be more marked in subjects younger than 60 years and overweight/obese subjects. Among participants without hypertension, proline and phenylalanine were associated with an increased risk of incident T2DM, while aspartic acid was associated with a decreased risk.

CONCLUSION

Serum proline was associated with the risk of incident T2DM in rural Chinese adults and might be a potential predictor.

Association between Iron Intake and Diabetic Peripheral Neuropathy in Type 2 Diabetes: Significance of Iron Intake and the Ratio between Iron Intake and Polyunsaturated Fatty Acids Intake

We aimed to investigate the association of iron and polyunsaturated fatty acid (PUFA) intake with diabetic peripheral neuropathy (DPN) in individuals with type 2 diabetes. This cross-sectional study included 147 individuals with type 2 diabetes. Dietary intake was assessed using three-day food records. DPN was diagnosed on the basis of a Michigan Neuropathy Screening Instrument—Physical Examination score ≥2.5. Adjusted for total energy intake, iron intake was significantly higher in individuals with DPN than in those without DPN (10.9 ± 4.0 mg vs. 9.9 ± 3.6 mg, p = 0.041). In addition, the iron/PUFA ratio was significantly higher in individuals with DPN (1.4 ± 0.8 vs. 1.1 ± 0.4, p = 0.005). Logistic regression analyses showed that iron intake (odds ratio (OR): 1.152; 95% confidence interval (CI): 1.012, 1.311) and iron/PUFA ratio (OR: 2.283; 95% CI: 1.066, 4.887) were associated with DPN after adjustment for total energy intake, sex, age, body mass index, systolic blood pressure, diabetes duration, estimated glomerular filtration rate, glycated hemoglobin, low-density lipoprotein cholesterol, and smoking. In conclusion, high dietary iron intake and an elevated iron/PUFA ratio were associated with the presence of DPN. The present study suggests the importance of the dietary pattern of iron and PUFA intake in individuals with type 2 diabetes.