Independent associations of fasting insulin, glucose, and glycated haemoglobin with stroke and coronary heart disease in older women

Continuous glucose monitoring metrics for earlier identification of pre-diabetes: protocol for a systematic review and meta-analysis

INTRODUCTION

Glycaemic variability and other metrics are not well characterised in subjects without diabetes. More comprehensive sampling as obtained with continuous glucose monitoring (CGM) may improve diagnostic accuracy of the transition from health to pre-diabetes. Our goal is to investigate the glycaemic system as it shifts from health to pre-disease in adult patients without diabetes using CGM metrics. New insights may offer therapeutic promise for reversing dysglycaemia more successfully with dietary, nutritional and lifestyle change before progression occurs to pre-diabetes and diabetes.

METHODS AND ANALYSIS

This systematic review will include comprehensive searches of the PubMed, Scopus, Cochrane Library and ClinicalTrials.gov databases, with restrictions set to studies published in the last 10 years in English and planned search date 10 March 2022. Reference lists of studies that meet eligibility criteria in the screening process will subsequently be screened for the potential inclusion of additional studies. We will include studies that examine CGM use and report diagnostic criteria such as fasting glucose and/or haemoglobin A1c such that we can assess correlation between CGM metrics and established diagnostic criteria and describe how CGM metrics are altered in the transition from health to pre-diabetes. The screening and data extraction will be conducted by two independent reviewers using Covidence. All included papers will also be evaluated for quality and publication bias using Cochrane Collaboration risk of bias tools. If there are two or more studies with quantitative estimates that can be combined, we will conduct a meta-analysis after assessing heterogeneity.

ETHICS AND DISSEMINATION

The systematic review methodology does not require formal ethical review due to the nature of the study design. Study findings will be publicly available and published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42022308222.

Diet pattern may affect fasting insulin in a large sample of black and white adults

OBJECTIVE

Dietary modification of insulin resistance may be a strategy for reducing chronic disease. For this study, we tested the hypothesis that higher fasting insulin, a marker for insulin resistance, would be related to diet patterns with a high proportion of carbohydrates, those with a high glycemic index, and those characterized by added sugar and processed starches.

STUDY DESIGN

Data were analyzed on 13,528 nondiabetic participants of the REasons for Geographic and Ethnic Differences in Stroke (REGARDS), an observational study of adults aged ≥45 years residing in 1855 counties across the continental USA. Information on habitual diet was collected using the Block 98 Food Frequency Questionnaire. Percent energy from carbohydrate, glycemic index, and glycemic load were determined for each participant, as well as adherence to five established diet patterns. Logistic regression was used to examine associations of baseline diet characteristics with odds for high fasting insulin [quartiles 3 and 4 (median = 98.9 pmol/L) vs. quartile 1], after adjusting for covariates.

RESULT

Greater percent carbohydrate, glycemic index, and glycemic load, and adherence to sweets/fat and southern diet patterns, was associated with greater odds for high insulin (P for trend <0.05 to <0.0001), whereas adherence to the plant-based and alcohol/salad patterns was associated with lower odds for high insulin (P for linear trend <0.0001).

CONCLUSION

In conclusion, diet pattern is associated with fasting insulin. Future studies are needed to determine if diet interventions designed to lower insulin, perhaps based on the patterns identified in this study, can improve risk for chronic disease.

Longitudinal Average Glucose Levels and Variance and Risk of Stroke: A Chinese Cohort Study

BACKGROUND

Diabetes is a known independent risk factor for stroke. However, whether higher glucose levels (126-139.9 mg/dl) can increase the risk of stroke in people without diabetes is still unknown. Moreover, as a fluctuating parameter, long-term glucose levels may also be related to the risk of stroke outcome. It is important to explore the correlation between long-term average blood glucose, as well as its variability, and stroke.

METHODS

We used 40,975 clinical measurements of glucose levels and 367 measurements of glycated hemoglobin A1c levels from 12,321 participants without stroke to examine the relationship between glucose levels and the risk of stroke. Participants were from the Weitang Geriatric Diseases study, including 5,707 men and 6,614 women whose mean age at baseline was 60.8 years; 1,011 participants had diabetes, and 11,310 did not. We estimated the long-term average blood glucose level based on the multilevel Bayesian model and fit in Cox regression models, stratified according to diabetes status.

RESULTS

Over a median follow-up period of 5 years, stroke developed in 279 of the 12,321 participants (244 without diabetes and 35 with). For people with an average glucose level of 126-139.9 mg per deciliter, compared with 90-99.9 mg per deciliter, the adjusted hazard ratio (HR) for total stroke was 1.78 (95% confidence interval (CI), 1.16-2.75), and the HR for levels higher than 140 mg per deciliter was 1.89 (95% CI, 1.09-3.29). Among those without diabetes whose glucose level was higher than 140 mg per deciliter, compared with 90-99.9 mg per deciliter, the adjusted HRs for total stroke and fatal stroke were 3.66 (95% CI, 1.47-9.08) and 5 (95% CI, 1.77-14.15), respectively. For a glucose standard deviation level higher than 13.83 mg per deciliter, compared with that lower than 5.91 mg per deciliter, the adjusted HR for total stroke was 2.31 (95% CI, 1.19-4.48).

CONCLUSIONS

Our results suggest that higher average glucose levels (126-139.9 mg/dl) and variance may be risk factors for stroke, even among people without diabetes diagnosis.

Homeostasis model assessment of insulin resistance and outcome of ischemic stroke in non-diabetic patients - a prospective observational study

Background

Insulin resistance (IR) in relation to diabetes is a risk factor for ischemic stroke (IS), whereas less is known about non-diabetic IR and outcome after IS.

Methods

In non-diabetic IS (n = 441) and controls (n = 560) from the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), IR was investigated in relation to IS severity and functional outcome. IR was evaluated acutely and after 3 months using the Homeostasis model assessment of IR (HOMA-IR). Stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS). Functional outcome was evaluated using the modified Rankin Scale (mRS) after 3 months, 2 and 7 years. Associations were evaluated by logistic regression.

Results

Higher acute and 3-month HOMA-IR was observed in IS compared to the controls (both p < 0.001) and in severe compared to mild IS (both p < 0.05). High acute HOMA-IR was associated with poor outcome (mRS 3–6) after 3 months and 7 years [crude Odds ratios (ORs), 95% confidence intervals (CIs) 1.50, 1.07–2.11 and 1.59, 1.11–2.30, respectively], but not after 2 years. These associations lost significance after adjustment for all covariates including initial stroke severity. In the largest IS subtype (cryptogenic stroke), acute HOMA-IR was associated with poor outcome after 2 years also after adjustment for age and stroke severity (OR 2.86, 95% CI 1.01–8.12).

Conclusions

In non-diabetic IS patients, HOMA-IR was elevated and related to stroke severity, but after adjustment for IS severity, the associations between HOMR-IR and poor outcome lost significance. This could suggest that elevated IR mostly is a part of the acute IS morbidity. However, in the subgroup of cryptogenic stroke, the associations with poor outcome withstood correction for stroke severity.

Relationship Between Glycated Hemoglobin and Stroke Risk: A Systematic Review and Meta-Analysis

BACKGROUND

Diabetes mellitus is a major risk factor for ischemic stroke. Rising hemoglobin A_1c (HbA_1c) levels are associated with microvascular diabetes mellitus complication development; however, this relationship has not been established for stroke risk, a macrovascular complication.

METHODS AND RESULTS

We conducted a systematic review and meta-analysis of observational cohort and nested case-control cohort studies assessing the association between rising HbA_1c levels and stroke risk in adults (≥18 years old) with and without type 1 or type 2 diabetes mellitus. Random-effects model meta-analyses were used to calculate pooled adjusted hazard ratios (HRs) and their precision. The systematic review yielded 36 articles, of which 29 articles (comprising n=532 779 participants) were included in our meta-analysis. Compared to non-diabetes mellitus range HbA_1c (<5.7%), diabetes mellitus range HbA_1c (≥6.5%) was associated with an increased risk of first-ever stroke with average HR (95% confidence interval) of 2.15 (1.76, 2.63), whereas pre-diabetes mellitus range HbA_1c (5.7-6.5%) was not (average HR [95% confidence interval], 1.19 [0.87, 1.62]). For every 1% HbA_1c increment (or equivalent), the average HR (95% confidence interval) for first-ever stroke was 1.12 (0.91, 1.39) in non-diabetes mellitus cohorts and 1.17 (1.09, 1.25) in diabetes mellitus cohorts. For every 1% HbA_1c increment, both non-diabetes mellitus and diabetes mellitus cohorts had a higher associated risk of first-ever ischemic stroke with average HR (95% confidence interval) of 1.49 (1.32, 1.69) and 1.24 (1.11, 1.39), respectively.

CONCLUSIONS

A rising HbA_1c level is associated with increased first-ever stroke risk in cohorts with a diabetes mellitus diagnosis and increased risk of first-ever ischemic stroke in non-diabetes mellitus cohorts. These findings suggest that more intensive HbA_1c glycemic control targets may be required for optimal ischemic stroke prevention.

Metabolic signatures of birthweight in 18 288 adolescents and adults

BACKGROUND

Lower birthweight is associated with increased susceptibility to cardiometabolic diseases in adulthood, but the underlying molecular pathways are incompletely understood. We examined associations of birthweight with a comprehensive metabolic profile measured in adolescents and adults.

METHODS

High-throughput nuclear magnetic resonance metabolomics and biochemical assays were used to quantify 87 circulating metabolic measures in seven cohorts from Finland and the UK, comprising altogether 18 288 individuals (mean age 26 years, range 15-75). Metabolic associations with birthweight were assessed by linear regression models adjusted for sex, gestational age and age at blood sampling. The metabolic associations with birthweight were compared with the corresponding associations with adult body mass index (BMI).

RESULTS

Lower birthweight adjusted for gestational age was adversely associated with cardiometabolic biomarkers, including lipoprotein subclasses, fatty acids, amino acids and markers of inflammation and impaired liver function (P < 0.0015 for 46 measures). Associations were consistent across cohorts with different ages at metabolic profiling, but the magnitudes were weak. The pattern of metabolic deviations associated with lower birthweight resembled the metabolic signature of higher adult BMI (R² = 0.77) assessed at the same time as the metabolic profiling. The resemblance indicated that 1 kg lower birthweight is associated with similar metabolic aberrations as caused by 0.92 units higher BMI in adulthood.

CONCLUSIONS

Lower birthweight adjusted for gestational age is associated with adverse biomarker aberrations across multiple metabolic pathways. Coherent metabolic signatures between lower birthweight and higher adult adiposity suggest that shared molecular pathways may potentially underpin the metabolic deviations. However, the magnitudes of metabolic associations with birthweight are modest in comparison to the effects of adiposity, implying that birthweight is only a weak indicator of the metabolic risk profile in adulthood.

Association of fasting glucose levels with incident atherosclerotic cardiovascular disease: An 8-year follow-up study in a Chinese population

BACKGROUND

Identification of the population at high risk of developing atherosclerotic cardiovascular disease (ASCVD) is critical for its prevention. The aim of the present study was to evaluate the use of fasting blood glucose (FBG) to predict ASCVD.

METHODS

In all, 18 610 participants, aged 35-74 years at enrollment, were included in this prospective study. Baseline information was collected using a standardized questionnaire, physical examinations, and laboratory tests. During follow-up, disease status and vital information were updated. Cox proportional hazards regression analysis was used to estimate associations, with normal FBG (70-99 mg/dL) as the reference group. Anthropometric measurements, socioeconomic status, and conventional cardiovascular risk factors were included in the multivariate-adjusted model.

RESULTS

After 7.8 years follow-up (145 223 person-years), there were 519 cases of ASCVD. The multivariate-adjusted hazard ratios (HR), with 95% confidence intervals (CI), for ASCVD in patients with low FBG (<70 mg/dL), impaired fasting glucose (IFG; 100-125 mg/dL), and diabetes (≥126 mg/dL, use of antidiabetic medication and/or self-report) were 1.35 (0.84, 2.15), 1.02 (0.81, 1.27), and 1.68 (1.26, 2.23), respectively. Although IFG was associated with the development of diabetes (multivariate-adjusted HR 3.67; 95% CI 3.20, 4.21), it was only associated with incident ASCVD in the univariate model (HR 1.52; 95% CI 1.23, 1.88). The association of diabetes with coronary heart disease was more pronounced than that with stroke. Gender and residential differences were also identified.

CONCLUSIONS

In the present study, IFG was associated with the development of diabetes but not incident ASCVD. Prevention strategies to reduce the development of diabetes in people with IFG are critical to improve cardiovascular health.

Normal fasting plasma glucose predicts type 2 diabetes and cardiovascular disease in elderly population in Taiwan

BACKGROUND

Hyperglycemia increases prevalence of metabolic syndrome (MetS), type 2 diabetes (T2D) and cardiovascular disease (CVD). But the role of normoglycemia on the development of T2D and CVD in elderly population remains unclear.

AIM

To determine an optimal cut-off for fasting plasma glucose (FPG) to predict MetS and subsequent risk of T2D and CVD in an elderly Taiwanese population with normal FPG levels.

DESIGN

Two stages included cross-sectional (Stage 1) and prospective (Stage 2) cohort study.

METHODS

In Stage 1 18 287 subjects aged  ≥60 years were enrolled; of these, 5039 without T2D and CVD advanced to Stage 2 and a mean follow-up of 3.8 years. MetS components were analysed, and in Stage 1, FPG cut-offs for MetS risk were calculated using receiver operating characteristic (ROC) curve analyses. In Stage 2, subjects without T2D and CVD in Stage 1 were classified into high-FPG and low-FPG groups based on cut-offs, and sex specific differences in incidence for T2D and CVD were calculated.

RESULTS

ROC curve analysis gave an optimal FPG cut-off for MetS of 93 mg/dl and 92 mg/dl for males and females, respectively. The high-FPG group had a 1.599- and 1.353-fold higher chance of developing T2D compared with the low-FPG group for males and females, respectively (95% CI: 1.606-2.721 and 1.000-1.831, P  =  0.015 and 0.05). The high-FPG group had a 1.24-fold higher chance of developing CVD for females (95% CI: 1.015-1.515, P  =  0.035); however, there was no difference for males.

CONCLUSIONS

Our results suggest that FPG within the normal range was associated with MetS, and elderly subjects with high normal levels have a higher incidence of developing T2D for both sexes, and CVD for females, over the short-term.

New and emerging biomarkers in cardiovascular disease

Cardiovascular disease (CVD) is the most common cause of death and disability worldwide. Therefore, great importance has been placed on the discovery of novel risk factors and metabolic pathways relevant in the prevention and management of CVD. Such research is ongoing and may continue to lead to better risk stratification of individuals and/or the development of new intervention targets and treatment options. This review highlights emerging biomarkers related to lipid metabolism, glycemia, inflammation, and cardiac damage, some of which show promising associations with CVD risk and provide further understanding of the underlying pathophysiology. However, their measurement methodology and assays will require validation and standardization, and it will take time to accumulate evidence of their role in CVD in various population settings in order to fully assess their clinical utility. Several of the novel biomarkers represent intriguing, potentially game-changing targets for therapy.

Insulin Resistance and Risk of Cardiovascular Disease in Postmenopausal Women

Background—

Insulin resistance is associated with diabetes mellitus, but it is uncertain whether it improves cardiovascular disease (CVD) risk prediction beyond traditional cardiovascular risk factors.

Methods and Results—

We identified 15 288 women from the Women’s Health Initiative Biomarkers studies with no history of CVD, atrial fibrillation, or diabetes mellitus at baseline (1993–1998). We assessed the prognostic value of adding fasting serum insulin, HOMA-IR (homeostasis model assessment–insulin resistance), serum-triglyceride-to-serum-high-density lipoprotein-cholesterol ratio TG/HDL-C, or impaired fasting glucose (serum glucose ≥110 mg/dL) to traditional risk factors in separate Cox multivariable analyses and assessed risk discrimination and reclassification. The study end point was major CVD events (nonfatal and fatal coronary heart disease and ischemic stroke) within 10 years, which occurred in 894 (5.8%) women. Insulin resistance was associated with CVD risk after adjusting for age and race/ethnicity with hazard ratios (95% confidence interval [CI]) per doubling in insulin of 1.21 (CI, 1.12–1.31), in HOMA-IR of 1.19 (CI, 1.11–1.28), in TG/HDL-C of 1.35 (CI, 1.26–1.45), and for impaired fasting glucose of 1.31 (CI, 1.05–1.64). Although insulin, HOMA-IR, and TG/HDL-C remained associated with increased CVD risk after adjusting for most CVD risk factors, none remained significant after adjusting for HDL-C: hazard ratios for insulin, 1.06 (CI, 0.98–1.16); for HOMA-IR, 1.06 (CI, 0.98–1.15); for TG/HDL-C, 1.11 (CI, 0.99–1.25); and for glucose, 1.20 (CI, 0.96–1.50). Insulin resistance measures did not improve CVD risk discrimination and reclassification.

Conclusions—

Measures of insulin resistance were no longer associated with CVD risk after adjustment for high-density lipoprotein-cholesterol and did not provide independent prognostic information in postmenopausal women without diabetes mellitus.

Clinical Trial Registration Information—

URL: http://www.clinicaltrial.gov . Unique identifier: NCT00000611.

Cardiovascular disease predicts diabetic peripheral polyneuropathy in subjects with type 2 diabetes: A 10-year prospective study

BACKGROUND

The relationship between cardiovascular disease and diabetic peripheral neuropathy is mainly sustained by data retrieved from cross-sectional studies focused on cardiovascular risk factors. We aimed to assess the presence of cardiovascular disease as a risk factor for developing diabetic peripheral neuropathy in a type 2 diabetes mellitus population.

METHOD

A 10-year prospective, primary care, multicentre study in a randomly selected cohort. Cardiovascular disease presence included stroke, coronary artery disease and/or peripheral ischaemia. Diabetic peripheral neuropathy diagnosis was based on clinical neurological examination as well as the neuropathy symptoms score and nerve conduction studies.

RESULTS

Three hundred and ten (N=310) patients were initially recruited. Two-hundred and sixty seven (N=267) patients were included in the study. Diabetic peripheral neuropathy cumulative incidence was 18.3% (95% confidence intervals 14.1-23.4; N=49). Diabetic peripheral neuropathy development was significantly more frequent in participants presenting with cardiovascular disease at baseline (P=0.01). In the final logistic regression analysis, the presence of cardiovascular disease remained associated with an increased risk for diabetic peripheral neuropathy (odds ratio 2.32, 95% confidence intervals 1.03-5.22) in addition to diabetes duration and low density lipoprotein-cholesterol levels.

CONCLUSIONS

In our series, type 2 diabetes mellitus patients with cardiovascular disease at baseline present with an increased risk of developing diabetic peripheral neuropathy at 10 years of follow-up. Our results suggest that measures aimed at the prevention, control and treatment of cardiovascular disease can also help prevent diabetic peripheral neuropathy development.

Novel metabolic biomarkers of cardiovascular disease

Coronary heart disease (CHD) accounts for one in every six deaths in US individuals. Great advances have been made in identifying important risk factors for CHD, such as hypertension, diabetes mellitus, smoking and hypercholesterolaemia, which have led to major developments in therapy. In particular, statins represent one of the greatest successes in the prevention of CHD. While these standard risk factors are important, an obvious opportunity exists to take advantage of ongoing scientific research to better risk-stratify individuals and to identify new treatment targets. In this Review, we summarize ongoing scientific research in a number of metabolic molecules or features, including lipoproteins, homocysteine, calcium metabolism and glycaemic markers. We evaluate the current state of the research and the strength of evidence supporting each emerging biomarker. We also discuss whether the associations with CHD are strong and consistent enough to improve current risk stratification metrics, and whether these markers enhance our understanding of the underlying biology of CHD and thus point towards new treatment options.

Glycated hemoglobin as a marker of subclinical atherosclerosis and cardiac remodeling among non-diabetic adults from the general population

BACKGROUND

Elevated glycated hemoglobin (HbA1c) is associated with increased risk of cardiovascular disease (CVD) and mortality but little is known about potential mechanisms underlying the reported associations.

METHODS

We used data from 1798 non-diabetic participants from the population-based cohort Study of Health in Pomerania (SHIP) to investigate cross-sectional and longitudinal associations of HbA1c with subclinical atherosclerosis (common carotid artery intima-media thickness [CCA-IMT]), cardiac structure (left ventricular mass [LVM]), and cardiac function (fractional shortening).

RESULTS

Cross-sectional analyses revealed a positive association between HbA1c and mean CCA-IMT with a 0.02 mm (95% confidence interval: 0.01-0.04) increase in CCA-IMT per 1% increase in HbA1c, and a similar positive trend across HbA1c quartiles (overall p-value <0.01). We also observed a graded association between HbA1c and high CCA-IMT (>75th percentile) with an odds ratio of 1.42 (95% CI: 1.11-1.81) per 1% increase in HbA1c. Longitudinal analyses showed no consistent associations of baseline HbA1c with mean follow-up CCA-IMT. There were no consistent associations of HbA1c with cardiac remodeling in cross-sectional and longitudinal analyses, respectively.

CONCLUSIONS

The association between HbA1c and CCA-IMT in non-diabetic adults may be a crucial link between high-normal HbA1c levels and an increased risk of CVD and mortality.

Plasma amino acid profiles are associated with insulin, C-peptide and adiponectin levels in type 2 diabetic patients

Objectives:

Plasma-free amino acid (PFAA) profiles have been associated with a future risk of developing diabetes or cardiovascular disease in nondiabetic subjects. These PFAA alterations might predominantly result from the metabolic shift caused by insulin resistance and visceral fat deposition. The variety of PFAA profiles within diabetic subjects is not well researched. In this study, we focused on type 2 diabetic subjects and examined the association between PFAA profiles and insulin- and glucose-related variables.

Methods:

Fifty-one Japanese subjects diagnosed with type 2 diabetes were recruited from an outpatient clinic. The plasma concentrations of 21 amino acids; glucose-related markers including glucose, hemoglobin A1c (HbA1c), glycoalbumin and 1,5-anhydroglucitol; insulin-related markers including insulin, C-peptide, and the homeostasis model assessment of insulin resistance; and adipocytokines including adiponectin and leptin were determined. The association of PFAA and other metabolic profiles were analyzed, and stratified analyses of the PFAAs and clinical characteristics were performed according to the fasting plasma insulin and HbA1c levels. In addition, the PFAA indices that correlate to visceral fat obesity were evaluated.

Results:

Although strong correlations between PFAAs and glucose-related markers were not observed, several amino acids (branched-chain amino acids, tryptophan, alanine, tyrosine, glutamate and proline) and PFAA indices that evaluate visceral obesity were highly correlated with insulin-related markers and adiponectin (P<0.001). In the group of diabetic patients with hyperinsulinemia, the amino acid levels were significantly increased, which generally demonstrated good concordance with insulin-related markers and adiponectin levels.

Conclusions:

The PFAA profiles in diabetic patients were strongly associated with hyperinsulinemia and hypoadiponectinemia, which might become risk evaluation factors for the development of cardiovascular diseases.

Fasting insulin concentrations and incidence of hypertension, stroke, and coronary heart disease: a meta-analysis of prospective cohort studies

BACKGROUND

Insulin resistance is a precursor of numerous chronic diseases, including cardiovascular disease (CVD). The fasting insulin concentration is considered a reasonable surrogate of insulin resistance, especially among nondiabetic individuals.

OBJECTIVE

We aimed to quantitatively summarize the literature on the association of fasting insulin concentrations with risk of hypertension, stroke, and coronary heart disease (CHD) by conducting a meta-analysis of prospective cohort studies.

DESIGN

Eligible studies were identified by searching PubMed and EMBASE through January 2013. Additional information was retrieved through Google Scholar or a hand review of the reference lists from relevant articles. Prospective cohort studies that reported RRs and corresponding 95% CIs for the association of interest were identified. Data were extracted independently by 2 investigators, and the weighted RRs and 95% CIs for the associations were obtained by using a random-effects model.

RESULTS

Of the 22 identified studies, 10 reported results on hypertension (36,617 individuals and 4491 cases), 7 on stroke (27,887 individuals and 1550 cases), and 9 on CHD (22,379 individuals and 1986 cases). Comparison of the highest with the lowest quantile of fasting insulin concentrations showed a pooled RR (95% CI) of 1.63 (1.35, 1.97) for hypertension, 1.18 (0.87, 1.60) for stroke, and 1.50 (1.28, 1.77) for CHD. Each 50-pmol/L increment in fasting insulin was associated with a 25% increase in risk of hypertension [RR: 1.25 (1.14, 1.36)] and a 16% increase in risk of CHD [RR: 1.16 (1.10, 1.22)] but was not associated with risk of stroke [RR: 0.999 (0.99, 1.01)].

CONCLUSIONS

A higher fasting insulin concentration or hyperinsulinemia was significantly associated with an increased risk of hypertension and CHD but not stroke. This meta-analysis suggests that early fasting insulin ascertainment in the general population may help clinicians identify those who are potentially at high risk of CVD.

Hemoglobin a1c is associated with increased risk of incident coronary heart disease among apparently healthy, nondiabetic men and women

BACKGROUND

Hemoglobin A1c (HbA1c), a time-integrated marker of glycemic control, predicts risk of coronary heart disease (CHD) among diabetics. Few studies have examined HbA1c and risk of CHD among women and men without clinically elevated levels or previously diagnosed diabetes.

METHODS AND RESULTS

We conducted parallel nested case-control studies among women (Nurses' Health Study) and men (Health Professionals Follow-up Study). During 14 and 10 years of follow-up, 468 women and 454 men developed incident nonfatal myocardial infarction (MI) and fatal CHD. Controls were matched 2:1 based on age, smoking, and date of blood draw. For these analyses, participants with a history of diabetes or HbA1c levels ≥6.5% at baseline were excluded. Compared with HbA1c of 5.0% to <5.5%, those with an HbA1c of 6.0% to <6.5% had a multivariable-adjusted relative risk (RR) of CHD of 1.90 (95% CI 1.11 to 3.25) in women and 1.81 (95% CI 1.09 to 3.03) in men. The pooled RR of CHD was 1.29 (95% CI 1.11 to 1.50) for every 0.5%-increment increase in HbA1c levels and 1.67 (95% CI 1.23 to 2.25) for every 1%-increment increase, with the risk plateauing around 5.0%. Furthermore, participants with HbA1c levels between 6.0% and <6.5% and C-reactive protein levels >3.0 mg/L had a 2.5-fold higher risk of CHD compared with participants in the lowest categories of both biomarkers.

CONCLUSIONS

Our findings suggest that HbA1c is associated with CHD risk among apparently healthy, nondiabetic women and men and may be an important early clinical marker of disease risk.

Glycated haemoglobin and the risk of cardiovascular disease, diabetes and all-cause mortality in the Copenhagen City Heart Study

OBJECTIVE

Individuals with diabetes mellitus (DM) have a considerably elevated risk of developing serious health problems including cardiovascular disease (CVD). Long-term elevated levels of blood glucose in nondiabetic individuals may also be associated with increased risk of CVD. The aim of this study was to investigate the relationships between glycated haemoglobin A(1c) (HbA(1c) ) and CVD, DM and all-cause mortality.

SUBJECTS AND DESIGN

The Copenhagen City Heart Study is a prospective study of individuals from the Danish general population. The cohort was followed for 10 years via national registers with respect to incident CVD, DM and all-cause mortality. Follow-up was 100% complete.

RESULTS

A total of 5127 subjects were included, of whom 597 had DM. In the nondiabetic population, HbA(1c) was significantly associated with incident CVD events in both univariate [hazard ratio (HR) 1.38, 95% CI 1.11-1.71] and multivariate analyses (HR 1.31, 95% CI 1.05-1.64). In the nondiabetic population, increased levels of HbA(1c) were correlated with developing DM. There was a threefold increase in risk of incident DM per unit increase in HbA(1c) with a univariate HR of 3.83 (95% CI 1.96-7.51). This relationship was essentially unchanged after multivariate adjustments (HR 4.19, 95% CI 2.01-8.71). Furthermore, we found that net reclassification improvement for diagnosed DM and CVD was significantly improved with the addition of HbA(1c) in the analyses. Although not statistically significant, we found a strong trend towards an association between HbA(1c) and all-cause mortality (HR 1.21, 95% CI 0.99-1.47). We did not find the same associations amongst the population with DM.

CONCLUSION

In the Danish general population, HbA(1c) was strongly associated with CVD in individuals without DM.

Insulin resistance and the risk of stroke and stroke subtypes in the nondiabetic elderly

Insulin resistance, which plays a key role in the development of diabetes mellitus, is a putative modifiable risk factor for stroke. The aim of this study was to investigate if markers of insulin resistance were associated with risk of stroke in the general elderly population. This study was part of the large population-based Rotterdam Study and included 5,234 participants who were aged 55 years or older and stroke free and diabetes free at baseline (1997-2001). Fasting insulin levels and homeostasis model assessment for insulin resistance were used as markers for insulin resistance. Cox regression was used to determine associations between insulin resistance markers and stroke risk, adjusted for age, sex, and potential confounders. During 42,806 person-years of follow-up (median: 8.6 years), 366 first-ever strokes occurred, of which 225 were cerebral infarctions, 42 were intracerebral hemorrhages, and 99 were unspecified strokes. Fasting insulin levels were not associated with risk of any stroke, cerebral infarction, or intracerebral hemorrhage. Homeostasis model assessment for insulin resistance, which almost perfectly correlated with fasting insulin levels, was also not associated with risk of stroke or stroke subtypes. In conclusion, in this population-based cohort study among nondiabetic elderly, insulin resistance markers were not associated with risk of stroke or any of its subtypes.

Effect of pre-diabetes on future risk of stroke: meta-analysis

OBJECTIVES

To assess the association between pre-diabetes and risk of stroke, and to evaluate whether this relation varies by diagnostic criteria for pre-diabetes.

DESIGN

Systematic review and meta-analysis of prospective studies.

DATA SOURCES

A search of Medline, Embase, and the Cochrane Library (1947 to 16 July 2011) was supplemented by manual searches of bibliographies of key retrieved articles and relevant reviews.

SELECTION CRITERIA

Prospective cohort studies that reported multivariate adjusted relative risks and corresponding 95% confidence intervals for stroke with respect to baseline pre-diabetes were included.

DATA EXTRACTION

Two independent reviewers extracted data on pre-diabetes status at baseline, risk estimates of stroke, study quality, and methods used to assess pre-diabetes and stroke. Relative risks were pooled using random effects models when appropriate. Associations were tested in subgroups representing different characteristics of participants and studies. Publication bias was evaluated with funnel plots.

RESULTS

The search yielded 15 prospective cohort studies including 760,925 participants. In 8 studies analysing pre-diabetes defined as fasting glucose 100-125 mg/dL (5.6-6.9 mmol/L), the random effects summary estimate did not show an increased risk of stroke after adjustment for established cardiovascular risk factors (1.08, 95% confidence interval 0.94 to 1.23; P = 0.26). In 5 studies analysing pre-diabetes defined as fasting glucose 110-125 mg/dL (6.1-6.9 mmol/L), the random effects summary estimate showed an increased risk of stroke after adjustment for established cardiovascular risk factors (1.21, 1.02 to 1.44; P = 0.03). In 8 studies with information about impaired glucose tolerance or combined impaired glucose tolerance and impaired fasting glucose, the random effects summary estimate showed an increased risk of stroke after adjustment for established cardiovascular risk factors (1.26, 1.10 to 1.43; P < 0.001). When studies that might have enrolled patients with undiagnosed diabetes were excluded, only impaired glucose tolerance or a combination of impaired fasting glucose and impaired glucose tolerance independently raised the future risk of stroke (1.20, 1.07 to 1.35; P = 0.002).

CONCLUSION

Pre-diabetes, defined as impaired glucose tolerance or a combination of impaired fasting glucose and impaired glucose tolerance, may be associated with a higher future risk of stroke, but the relative risks are modest and may reflect underlying confounding.

Effects of chocolate, cocoa, and flavan-3-ols on cardiovascular health: a systematic review and meta-analysis of randomized trials

BACKGROUND

There is substantial interest in chocolate and flavan-3-ols for the prevention of cardiovascular disease (CVD).

OBJECTIVE

The objective was to systematically review the effects of chocolate, cocoa, and flavan-3-ols on major CVD risk factors.

DESIGN

We searched Medline, EMBASE, and Cochrane databases for randomized controlled trials (RCTs) of chocolate, cocoa, or flavan-3-ols. We contacted authors for additional data and conducted duplicate assessment of study inclusion, data extraction, validity, and random-effects meta-analyses.

RESULTS

We included 42 acute or short-term chronic (≤18 wk) RCTs that comprised 1297 participants. Insulin resistance (HOMA-IR: -0.67; 95% CI: -0.98, -0.36) was improved by chocolate or cocoa due to significant reductions in serum insulin. Flow-mediated dilatation (FMD) improved after chronic (1.34%; 95% CI: 1.00%, 1.68%) and acute (3.19%; 95% CI: 2.04%, 4.33%) intakes. Effects on HOMA-IR and FMD remained stable to sensitivity analyses. We observed reductions in diastolic blood pressure (BP; -1.60 mm Hg; 95% CI: -2.77, -0.43 mm Hg) and mean arterial pressure (-1.64 mm Hg; 95% CI: -3.27, -0.01 mm Hg) and marginally significant effects on LDL (-0.07 mmol/L; 95% CI: -0.13, 0.00 mmol/L) and HDL (0.03 mmol/L; 95% CI: 0.00, 0.06 mmol/L) cholesterol. Chocolate or cocoa improved FMD regardless of the dose consumed, whereas doses >50 mg epicatechin/d resulted in greater effects on systolic and diastolic BP. GRADE (Grading of Recommendations, Assessment, Development and Evaluation, a tool to assess quality of evidence and strength of recommendations) suggested low- to moderate-quality evidence of beneficial effects, with no suggestion of negative effects. The strength of evidence was lowered due to unclear reporting for allocation concealment, dropouts, missing data on outcomes, and heterogeneity in biomarker results in some studies.

CONCLUSIONS

We found consistent acute and chronic benefits of chocolate or cocoa on FMD and previously unreported promising effects on insulin and HOMA-IR. Larger, longer-duration, and independently funded trials are required to confirm the potential cardiovascular benefits of cocoa flavan-3-ols.

Could NICE guidance on the choice of blood pressure lowering drugs be simplified?

Reecha Sofat and colleagues argue that prescribing advice needs updating in the light of recent evidence that all classes of blood pressure lowering drugs are broadly equivalent

Takeaway food consumption and cardio-metabolic risk factors in young adults

BACKGROUND/OBJECTIVES

Takeaway food consumption is positively associated with adiposity. Little is known about the associations with other cardio-metabolic risk factors. This study aimed to determine whether takeaway food consumption is associated with fasting glucose, insulin, lipids, homeostasis model assessment (HOMA) and blood pressure.

SUBJECTS/METHODS

A national sample of 1896, 26-36 year olds completed a questionnaire on socio-demographics, takeaway food consumption, physical activity and sedentary behaviour. Waist circumference and blood pressure were measured, and a fasting blood sample was taken. For this analysis, takeaway food consumption was dichotomised to once a week or less and twice a week or more. Linear regression was used to calculate differences in the adjusted mean values for fasting lipids, glucose, insulin, HOMA and blood pressure. Models were adjusted for age, employment status, leisure time physical activity and TV viewing.

RESULTS

Compared with women who ate takeaway once a week or less, women who ate takeaway twice a week or more had significantly higher adjusted mean fasting glucose (4.82 vs 4.88 mmol/l, respectively; P=0.045), higher HOMA scores (1.27 vs 1.40, respectively, P=0.034) and tended to have a higher mean fasting insulin (5.95 vs 6.45 mU/l, respectively, P=0.054). Similar associations were observed for men for fasting insulin and HOMA score, but the differences were not statistically significant. For both women and men adjustment for waist circumference attenuated the associations.

CONCLUSION

Consuming takeaway food at least twice a week was associated with cardio-metabolic risk factors in women but less so in men. The effect of takeaway food consumption was attenuated when adjusted for obesity.

Haemoglobin A1c levels and subsequent cardiovascular disease in persons without diabetes: a meta-analysis of prospective cohorts

AIMS/HYPOTHESIS

The aim of this meta-analysis was to determine the relationship between HbA(1c) levels and subsequent cardiovascular outcomes in individuals without diabetes.

METHODS

We searched Medline, Embase and Scopus from initiation of the study until the end of 2009. One reviewer searched and another verified findings. Data were extracted by one reviewer and verified by another. We accepted prospective studies in any language reporting three or more quartiles for HbA(1c) levels. Within quartiles, authors must have presented both numbers of patient-years at risk and cardiovascular outcomes. Outcomes per person-time at risk were regressed on average HbA(1c) values using Poisson regression. We pooled β coefficients using Cochran's semi-weighted (inverse variance) random-effects model. Study quality was assessed using the Downs-Black scale.

RESULTS

We investigated 16 datasets (nine for total cardiovascular events and seven for death) from five papers with 44,158 patients (44% men) over 404,899 patient-years of follow-up. There were 1,366 cardiovascular deaths (3.1%; 3.37/1,000 person-years) and 2,142 cardiovascular events (4.9%; 5.29/1,000 person-years). The overall meta-analytic β coefficients were 0.720 (95% CI 0.307-1.133) and 0.757 (95% CI 0.382-1.132) for cardiac death and events, respectively. Compared with the baseline value of 0.0427, an HbA(1c) level of 0.05 was associated with a relative risk for cardiovascular death of 1.13 (95% CI 1.05-1.21), a 0.06 value with 1.34 (95% CI 1.13-1.58), and a 0.07 HbA(1c) with relative risk 1.58 (95% CI 1.22-2.06). Results for total cardiovascular events were similar. The average study quality was 0.7 (70%).

CONCLUSIONS/INTERPRETATION

We conclude that HbA(1c) was significantly associated with cardiovascular events and deaths in persons without diabetes.

Demographic and cardiovascular risk factors modify association of fasting insulin with incident coronary heart disease and ischemic stroke (from the Atherosclerosis Risk In Communities Study)

Previous studies have reported an association between circulating insulin and incident cardiovascular disease, but limited knowledge is available on the association across subgroups. We examined the associations of fasting insulin with incident coronary heart disease (CHD) and ischemic stroke in multiple subgroups of a biracial, middle-age cohort. A total of 12,323 subjects were included in the analysis. The incidence of CHD (n = 960) and ischemic stroke (n = 445) through 2005 was determined through annual interviews, repeat examinations, and community surveillance. Serum insulin was measured at baseline. Cox regression analysis was used to estimate the hazard ratios by quintile of fasting insulin at baseline and to determine the significance of effect modification. In the minimally adjusted models (age, gender, race, and field center), the baseline fasting insulin quintile was positively associated with both incident CHD (hazard ratio per quintile insulin = 1.12, p-trend <0.0001) and ischemic stroke (hazard ratio per quintile insulin = 1.11, p = 0.0018). The adjustment for high-density lipoprotein completely attenuated the association of insulin with CHD but not with stroke. The associations of insulin with CHD were stronger in nonsmokers (p-interaction = 0.018) and in those without hypertension (p-interaction = 0.0087). The associations of insulin with stroke were stronger in women (p-interaction = 0.037), whites (compared to blacks; p-interaction = 0.036), and those without hypertension (p-interaction = 0.0027).

New diagnosis criteria for diabetes with hemoglobin A1c and risks of macro-vascular complications in an urban Japanese cohort: the Suita study

The association of the new diagnosis criteria for diabetes adopting hemoglobin A1c, recently proposed by the international expert committee, with macro-vascular complications was tested in a 12-year population-based cohort. The present analysis suggested that this new criteria were applicable to macro-vascular complications in the Japanese.

Fasting plasma glucose in non-diabetic participants and the risk for incident cardiovascular events, diabetes, and mortality: results from WOSCOPS 15-year follow-up

AIMS

The evidence base for fasting plasma glucose (FPG) in the non-diabetic range as a risk factor for cardiovascular disease (CVD) is inconclusive. We investigated this question in the West of Scotland Coronary Prevention Study (WOSCOPS).

METHODS AND RESULTS

In WOSCOPS, we related FPG in 6447 men (mean age 55 years) with hypercholesterolaemia, but no history of CVD or diabetes, to the risk of cardiovascular events and mortality over 14.7 years of follow-up; 2381 non-fatal/fatal cardiovascular events and 1244 deaths occurred. Participants were divided into fifths of baseline FPG, Q1 (< or =4.3 mmol/L) to Q5 (>5.1-6.9 mmol/L). Q2 was designated the referent based on previous studies which have suggested a J-shaped relationship between FPG and CVD. Compared with Q2 (>4.3-4.6 mmol/L), men in Q5 had no elevated risk for cardiovascular events [hazard ratio (HR) 0.95 (0.83-1.08)], or all-cause mortality [HR 0.96 (0.80-1.15)] in fully adjusted analyses despite a significant risk for incident diabetes [HR 22.05 (10.75-45.22)]. After further dividing Q5 into fifths, Q5a-e, individuals in Q5e (FPG 5.8-6.9 mmol/L) were also not at increased risk of cardiovascular events [HR 1.05 (0.82-1.35)] or other endpoints compared with Q2. All results were similar using Q1 as the referent.

CONCLUSION

Elevations in FPG in the non-diabetic range were not associated with long-term risk of cardiovascular events in middle-aged men in WOSCOPS. These data suggest that the current FPG cutoff for diagnosing diabetes also appropriately identifies western men at risk of CVD.

HOMA insulin sensitivity index and the risk of all-cause mortality and cardiovascular disease events in the general population: the Australian Diabetes, Obesity and Lifestyle Study (AusDiab) study

AIMS/HYPOTHESIS

We assessed whether the relationships between insulin sensitivity and all-cause mortality as well as fatal or non-fatal cardiovascular disease (CVD) events are independent of elevated blood glucose, high blood pressure, dyslipidaemia and body composition in individuals without diagnosed diabetes.

METHODS

Between 1999 and 2000, baseline fasting insulin, glucose and lipids, 2 h plasma glucose, HbA(1c), anthropometrics, blood pressure, medication use, smoking and history of CVD were collected from 8,533 adults aged >35 years from the population-based Australian Diabetes, Obesity and Lifestyle study. Insulin sensitivity was estimated by HOMA of insulin sensitivity (HOMA-%S). Deaths and fatal or non-fatal CVD events were ascertained through linkage to the National Death Index and medical records adjudication.

RESULTS

After a median of 5.0 years there were 277 deaths and 225 CVD events. HOMA-%S was not associated with all-cause mortality. Compared with the most insulin-sensitive quintile, the combined fatal or non-fatal CVD HR (95% CI) for quintiles of decreasing HOMA-%S were 1.1 (0.6-1.9), 1.4 (0.9-2.3), 1.6 (1.0-2.5) and 2.0 (1.3-3.1), adjusting for age and sex. Smoking, CVD history, hypertension, lipid-lowering medication, total cholesterol and waist-to-hip ratio moderately attenuated this relationship. However, the association was rendered non-significant by adding HDL. Fasting plasma glucose, but not HOMA-%S significantly improved the prediction of CVD, beyond that seen with other risk factors.

CONCLUSIONS/INTERPRETATION

In this cohort, HOMA-%S showed no association with all-cause mortality and only a modest association with CVD events, largely explained by its association with HDL. Fasting plasma glucose was a better predictor of CVD than HOMA-%S.

Prevalence of cardiovascular disease and risk factors in a type 2 diabetic population of the North Catalonia diabetes study

PURPOSE

The purpose of the study was to evaluate the prevalence of cardiovascular disease (CVD), cardiovascular risk factors (CVRFs), and their control in patients with type 2 diabetes mellitus (T2DM) at primary care settings from the North Catalonia Diabetes Study (NCDS).

DATA SOURCES

In this multicentre cross-sectional descriptive study, data were collected from a random sample of 307 patients with T2DM. The prevalence of CVD, CVRF, metabolic syndrome (MS), coronary heart disease (CHD) risk at 10 years (Framingham Point Scores), and CVRF control was evaluated. MS and lipid profiles were established according to Adult Treatment Panel III criteria.

CONCLUSIONS

CVD prevalence was 22.0% (CHD: 18.9% and peripheral ischemia: 4.5%) and more frequent in men. The prevalence of selected CVRF was: hypertension: 74.5%; dyslipidemia: 77.7%; smoking: 14.9%; obesity 44.9%, and familial CVD: 38.4%. Three or more CVRFs, including T2DM, were observed in 91.3%. MS prevalence was 68.7%. Framingham score was 10.0%, higher in men than in women. CVD prevalence was related to: age, number of CVRFs, duration of diabetes, familial history of CVD, waist circumference, hypertension, lipid profile, kidney disease, and Framingham score, but not to MS by itself. Correct lipid profiles and blood pressure were only observed in 18.9% and 24.0%, respectively, whereas platelet aggregation inhibitors were only recorded in 16.1% of the patient cohort. MS presence was not an independent risk factor of CVD in our study.

IMPLICATIONS FOR PRACTICE

The high prevalence of CVD and an inadequate control of CVRF, which were apparent in the NCDS population, would suggest that advanced practice nurses should consider incorporating specific cardiovascular assessment in their routine care of persons with T2DM.

Coronary heart disease risk factors in adult premenopausal white women with polycystic ovary syndrome compared with a healthy female population

Our specific aim was to determine whether coronary heart disease (CHD) risk factors in polycystic ovary syndrome (PCOS) patients were independent of their higher body mass index (BMI) and centripetal obesity. In adult, premenopausal, white women, CHD risk factors were compared between 488 patients with well-defined PCOS and 351 healthy free-living population controls from the Princeton Follow-up Study (PFS). After excluding women with irregular menses (putative PCOS phenotypes), comparisons were also made between the 261 PFS women with a history of regular menses and the 488 women with PCOS. Fasting lipids, insulin, glucose, homeostasis model assessment of insulin resistance (HOMA-IR), HOMA insulin secretion, blood pressure, BMI, and waist circumference were measured. Compared with both the full cohort of 351 PFS women and the subgroup of 261 PFS women with regular menses, women with PCOS had higher BMI, waist circumference, total and low-density lipoprotein cholesterol, triglyceride, systolic blood pressure, diastolic blood pressure, insulin, glucose, and HOMA-IR (all Ps < or = .005). After adjusting for age and BMI, women with PCOS, compared with the 351 and 261 PFS women, had lower high-density lipoprotein cholesterol (P < .0001, .0008) and higher systolic blood pressure (P = .0002, < .0001), insulin (P = .017, .039), HOMA-IR (P = .013, .032), and HOMA insulin secretion (P = .022, .037). The small subgroup of PCOS women with normal BMI (<25 kg/m(2)) (36/488, 7%) also had higher age-adjusted insulin, glucose, and HOMA-IR (all Ps < .005) than the subgroup of PFS women with BMI less than 25 kg/m(2) (123/261, 47%). Increased CHD risk factors and high HOMA-IR in PCOS cannot be exclusively attributed to their preponderant centripetal obesity. Identification of women with clinical features of PCOS should alert the clinician to potentially increased risk for CHD and prompt CHD risk factor testing.

Independent association of HbA(1c) and incident cardiovascular disease in people without diabetes

Recent studies have reported no association between elevated glycated hemoglobin (HbA(1c)) and incident cardiovascular disease (CVD) among women without diabetes. This study describes associations between HbA(1c) and new onset CVD in a representative adult population cohort. Assessment of participants in The North West Adelaide Health Study (NWAHS), a population study of randomly selected adults (age > or =18 years, n = 4,060), included measurement of height, weight, blood pressure, fasting lipids, glucose, and HbA(1c). A self-completed questionnaire assessed doctor-diagnosed diabetes, CVD and stroke, smoking status, and demographics. The cohort was followed for an average 3.5 years. Of the 2,913 adults free of diabetes at baseline and follow-up, 94 (3.5%) reported new onset coronary heart disease (CHD) and/or stroke. Compared with those with an HbA(1c) < or =5.0%, risk of new onset CVD was increased in those with HbA(1c) 5.4-5.6% (odds ratio (OR) 2.5, 95% confidence interval (CI) 1.4, 4.6), and > or =5.7% (OR 1.9, 95% CI 1.1, 3.4), after adjustment for other risk factors. The association was stronger in women than men (P = 0.03), and attenuated to only a small degree by addition of impaired fasting glucose (IFG), hypertension, hypercholesterolemia, BMI, waist circumference, or smoking to the model. Elevated HbA(1c) is related to new onset CVD over a relatively short follow-up period in both men and women without diabetes and who do not develop diabetes, after adjustment for other major risk factors. Unlike previous studies, this relationship was not substantially attenuated by other traditional risk factors.

Fasting blood glucose and the risk of stroke and myocardial infarction

BACKGROUND

Although diabetes is a well-known risk factor of atherosclerotic cardiovascular diseases, the cardiovascular disease risk of glycemia below the current diabetic threshold remains uncertain.

METHODS AND RESULTS

A total of 652,901 Korean men aged 30 to 64 years from the Korean National Health Insurance System were categorized into 8 groups by fasting blood glucose (FBG) level at baseline and were followed up for cardiovascular diseases occurrence during 1992-2001. Over the follow-up period of 8.8 years, 10,954 stroke and 3766 myocardial infarction events occurred. In age-adjusted analyses, there was evidence of linear associations between FBG and myocardial infarction, ischemic stroke, and intracerebral hemorrhagic stroke. However, with additional adjustment for socioeconomic position, behaviors, and other cardiovascular disease risk factors, the associations with myocardial infarction and intracerebral hemorrhagic stroke were markedly attenuated with increased risk only at the highest FBG levels (> or =7.5 mmol/L). With full adjustment, the association with ischemic stroke persisted; a linear increase in the risk of ischemic stroke was observed from FBG level of 5.6 mmol/L. When the analyses were repeated with those persons who had been diagnosed with diabetes removed, there was no evidence of associations of FBG with intracerebral hemorrhagic stroke, but the association with ischemic stroke persisted.

CONCLUSIONS

In this Korean male population, the association with high FBG differed between ischemic stroke, intracerebral hemorrhagic stroke, and myocardial infarction. The linear increase in the risk of ischemic stroke, independently of other cardiovascular risk factors, was observed at a level below the current FBG criteria for impaired fasting glucose (> or =5.6 mmol/L). However, for other cardiovascular diseases, the current cutoff for diagnosing diabetes appropriately identified Korean men at risk.

Novel association of HK1 with glycated hemoglobin in a non-diabetic population: a genome-wide evaluation of 14,618 participants in the Women's Genome Health Study

Type 2 diabetes is a leading cause of morbidity and mortality. While genetic variants have been found to influence the risk of type 2 diabetes mellitus, relatively few studies have focused on genes associated with glycated hemoglobin, an index of the mean blood glucose concentration of the preceding 8-12 weeks. Epidemiologic studies and randomized clinical trials have documented the relationship between glycated hemoglobin levels and the development of long-term complications in diabetes; moreover, higher glycated hemoglobin levels in the subdiabetic range have been shown to predict type 2 diabetes risk and cardiovascular disease. To examine the common genetic determinants of glycated hemoglobin levels, we performed a genome-wide association study that evaluated 337,343 SNPs in 14,618 apparently healthy Caucasian women. The results show that glycated hemoglobin levels are associated with genetic variation at the GCK (rs730497; P = 2.8 x 10(-12)), SLC30A8 (rs13266634; P = 9.8 x 10(-8)), G6PC2 (rs1402837; P = 6.8 x 10(-10)), and HK1 (rs7072268; P = 6.4 x 10(-9)) loci. While associations at the GCK, SLC30A8, and G6PC2 loci are confirmatory, the findings at HK1 are novel. We were able to replicate this novel association in an independent validation sample of 455 additional non-diabetic men and women. HK1 encodes the enzyme hexokinase, the first step in glycolysis and a likely candidate for the control of glucose metabolism. This observed genetic association between glycated hemoglobin levels and HK1 polymorphisms paves the way for further studies of the role of HK1 in hemoglobin glycation, glucose metabolism, and diabetes.

Fasting insulin levels and cognitive decline in older women without diabetes

BACKGROUND

Type 2 diabetes has been associated with an increased risk of dementia. To assess possible independent effects of insulin, we investigated the relation of insulin levels to cognitive decline in nondiabetic women.

METHODS

Fasting plasma insulin levels were measured in mid-life in 1,416 nondiabetic Nurses' Health Study participants, who also completed cognitive testing that began 10 years later (current age: 70-75 years). Over 4 years, 3 assessments of general cognition, verbal memory, category fluency and attention were administered. Primary outcomes were the Telephone Interview for Cognitive Status (TICS) performance, the global score (average of all tests) and verbal memory (average of verbal recall tests). Linear mixed-effects models were used to calculate the association between insulin and cognitive decline.

RESULTS

Higher insulin levels were associated with a faster decline on the TICS and verbal memory. For analysis, batch-specific quartiles of insulin levels were constructed. Compared to the lowest quartile, adjusted differences in the annual rates of decline (with 95% CI values in parentheses) for the second, third and fourth quartiles were: TICS, -0.06 (-0.16, 0.03), -0.14 (-0.24, -0.04), and -0.09 (-0.19, 0.01) points (p trend = 0.04); verbal memory, -0.01 (-0.04, 0.02), -0.05 (-0.08, -0.02), and -0.02 (-0.05, 0.01) units (p trend = 0.02). These associations remained after multivariable adjustment.

CONCLUSIONS

Our study provides evidence for a potential role of higher fasting insulin levels in cognitive decline, possibly independent of diabetes.