Glycated hemoglobin level is strongly related to the prevalence of carotid artery plaques with high echogenicity in nondiabetic individuals: the Tromsø study

Association between Hemoglobin A1c and Renal Arteriolar Sclerosis in Subjects Presenting without any Apparent Kidney Dysfunction

AIMS

Diabetic kidney disease is a major vascular complication in patients with diabetes mellitus (DM). However, the association between the hemoglobin (Hb)A1c levels, notably the prediabetic levels, and renal pathological changes remains unclear. We investigated the association between the HbA1c levels and renal arteriolar lesions in subjects without any apparent kidney dysfunction using a living kidney donor cohort.

METHODS

Between January 2006 and May 2016, 393 living kidney donors underwent a "zero-time" biopsy at Kyushu University Hospital. The patients were divided into four groups (HbA1c levels ＜5.6%, 5.6%-5.7%, 5.8%-6.4%, and ≥ 6.5%, or diagnosed with DM [DM group]). Renal arteriolar hyalinization and wall thickening were assessed using semi-quantitative grading. We then investigated the association between the HbA1c levels and renal pathological changes.

RESULTS

158 (40.2%) patients had arteriolar hyalinization and 148 (37.6%) showed wall thickening. A significant correlation was observed between the HbA1c levels and wall thickening (p for trend ＜0.001). An elevated HbA1c level was significantly associated with wall thickening according to a multivariable logistic analysis in subjects with HbA1c levels of 5.6%-5.7% and 5.8%-6.4%, and the DM group, compared with those with HbA1c levels of ＜5.6% (odds ratio [OR], 1.91; 95% confidence interval [CI]: [1.03-3.54] for 5.6%-5.7%, OR, 1.96; 95% CI: [1.09-3.53] for 5.8%-6.4%, and OR, 2.86; 95% CI: [0.91-9.01] for the DM group), whereas arteriolar hyalinization did not increase within the nondiabetic HbA1c levels.

CONCLUSIONS

Elevated high-normal HbA1c levels are considered to be independent risk factors for arteriolar wall thickening. Subclinical renal arteriolar sclerosis may develop in patients with prediabetic HbA1c levels.

Association between glycated hemoglobin and functional outcomes in patients with intracranial large artery atherosclerotic disease-related acute ischemic stroke: identifying the magic number

Objective

This study aimed to investigate the effect of the glycated hemoglobin A1c (HbA1c) level on the functional outcome (FOC) in patients with intracranial large artery atherosclerotic disease (ICLAD)-related acute ischemic stroke (AIS).

Methods

This retrospective study enrolled patients with ICLAD-related AIS who were admitted to King Fahd University Hospital between January 2017 and September 2021. Patients were divided into two groups based on the optimal cutoff HbA1c level determined using receiver operating characteristic curve analysis-those with HbA1c ≤6.9% and those with HbA1c >6.9%. Demographic and other clinical characteristics were compared between the two groups using chi-square tests. The association between HbA1c and 90-day FOC was assessed using the chi-square test and odds ratios (ORs). Multivariate analysis was performed to adjust for confounding factors.

Results

A total of 140 patients were included in the analysis. A significant association was observed between the HbA1c level and FOC. Compared to patients with HbA1c ≤6.9%, patients with HbA1c >6.9% were more likely to have an unfavorable FOC [p = <0.001, OR = 2.05, 95% confidence interval (CI) = 1.33-3.14]. The association between HbA1c >6.9% and unfavorable FOC was sustained even after adjusting for confounding factors (p = 0.008) and atherosclerosis risk factors (p = 0.01). HbA1c >6.9% was also associated with higher ORs for in-hospital complications (p = 0.06, OR = 1.34, 95% CI = 1.02-1.77) and mortality (p = 0.07, OR = 1.42, 95% CI = 1.06-1.92) although these associations did not attain significant p-values.

Conclusion

HbA1c >6.9% was significantly associated with unfavorable FOC in ICLAD-related AIS. However, further studies with larger sample sizes are required to verify whether HbA1c is an independent predictor of poor FOC. Nevertheless, targeting HbA1c <7% should be the goal of physicians when managing patients at high risk of ICLAD.

Association of HbA1c with carotid artery plaques in patients with coronary heart disease: a retrospective clinical study

BACKGROUND AND AIMS

Haemoglobin A1c (HbA1c) levels have been shown to be related to carotid artery plaques. However, studies on the relationship between HbA1c levels and carotid artery plaques in patients with coronary heart disease (CHD) are limited and inconsistent. Our objective was to examine the correlation between HbA1c levels and carotid artery plaques in patients with CHD.

METHODS

The study comprised 9275 Chinese adults with CHD from January 1, 2014, to September 30, 2020. HbA1c levels were assessed, and colour Doppler ultrasound was used to evaluate the carotid artery, including plaque presence, intima-media thickness, and plaque echo properties, to investigate the association between HbA1c and carotid plaque. A logistic regression model was used to assess the association between carotid artery plaques, carotid plaque echogenicity, and HbA1c.

RESULTS

The HbA1c level of the plaque-present group was higher than that of the plaque-absent group [6.1 (5.6-7.2) vs. 5.8 (5.5-6.5), p < 0.001]. In multiple linear regression analysis, intima-media thickness was associated with HbA1c (p < 0.001). Logistic regression showed that a higher HbA1c level was associated with plaque incidence as well as hyperechoic and heterogeneous plaques (p < 0.001). These associations persist after adjusting for age, sex, blood pressure, lipid profiles, alcohol consumption, and tobacco exposure.

CONCLUSION

HbA1c levels are notably associated with carotid artery plaque incidence, intima-media thickness, and plaque echogenicity in patients with CHD. These findings show that different levels of HbA1c may be an indicator for carotid artery plaques and thus, should be observed in patients with CHD.

Does psychosocial stress modify the association of fine particulate matter and ozone with cardiovascular health indicators?

Fine particulate matter (PM_2.5) and ozone (O₃) air pollution can cause abnormal changes in blood pressure (BP), blood glucose and lipids, which are important indicators for cardiovascular health. Psychosocial stress could be a potential effect modifier for adverse health effects of air pollution, but research evidence is scarce. A cross-sectional study with 373 elderly subjects was conducted in Beijing during 2018-2019. We collected psychosocial stress information on anxiety, perceived stress and depression, obtained daily environmental data, measured resting BP, blood glucose and lipids in study participants, and analyzed the associations of PM_2.5 or O₃ with cardiovascular health indicators and the modification effect by psychosocial stress. Results showed that PM_2.5 was significantly associated with increased systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) ; and O₃ was significantly associated with elevated DBP, glycated hemoglobin (HbA1c) and total triglyceride (TG). In addition, the associations of PM_2.5 with TG, and O₃ with SBP and TG were higher in participants with high psychosocial stress, whereas the associations of O₃ with high-density lipoprotein cholesterol (HDL-C) were higher in participants with low psychosocial stress. For an interquartile range (IQR) (56.8 μg/m³) increase in PM_2.5 at 4-d moving average, TG increased by 21.43% (95% CI: 2.90, 43.29) in high perceived-stress group, and decreased by 20.05% (95% CI: -30.31, -8.28) in low perceived-stress group (p for interaction = 0.04). For an IQR (63.0 μg/m³) increase in O₃ at 2-d moving average, TG increased by 32.01% (95% CI: 7.65, 61.89) in high perceived-stress group, and increased by 7.95% (95% CI: -9.80, 29.20) only in low perceived-stress group (p for interaction = 0.04). For an IQR (64.0 μg/m³) increase in O₃ at 3-d moving average, HDL-C decreased by 4.55% (95% CI: -12.15, 3.72) in high perceived-stress group, and increased by 0.57% (95% CI: -6.99, 8.75) in low perceived-stress group (p for interaction=0.002). In conclusion, our results indicated that short-term exposures to PM_2.5 and O₃ were associated with significant changes in BP, blood glucose and lipids, and psychosocial stress may increase the susceptibility of the participants to the adverse cardiovascular effects of PM_2.5 and O₃.

Prospective study of hemoglobin A1c and incident carotid artery plaque in Chinese adults without diabetes

Background

Diabetes has been reported to be associated with carotid artery plaque (CAP). However, it remains unclear whether hemoglobin A1c (HbA1c) level, a marker for long-term glycemic status, is associated with altered CAP risk in individuals with fasting blood glucose (FBG) concentrations below the current cutoff for diabetes.

Methods

Included were 16,863 Chinese adults (aged 18 years or more; 9855 men and 7008 women) with fasting blood glucose < 7.0 mmol/L at baseline (2013). Both HbA1c level and CAP (assessed via ultrasound B-mode imaging) were annually assessed during 2014–2018. All the participants were further classified into three groups based on baseline HbA1c level: ≤ 5.6%, 5.7–6.4%, and ≥ 6.5%. We used Cox proportional-hazards model to evaluate the association between HbA1c level and incident CAP, adjusting for a series of potential confounders.

Results

During 5 years of follow up, 3942 incident CAP cases were identified. Individuals with higher baseline HbA1c had higher future risk of CAP (p-trend < 0.001). In the full-adjusted model, each percent increase of HbA1c was associated with a 56% (HR = 1.56, 95% CI 1.37, 1.78) higher risk of CAP. Excluding participants with chronic inflammation, as assessed by high-sensitivity C-reactive protein and white blood cell, and those with FBG ≥ 5.6 mmol/L at baseline generated similar results.

Conclusions

Elevated HbA1c level was associated with high risk of developing CAP in Chinese adults without FBG defined diabetes.

Correlation of Glycosylated Hemoglobin Levels with Histological and Ultrasound Characteristics of the Carotid Plaque in Diabetic and Nondiabetic Patients

BACKGROUND

The purpose of this study is to investigate the correlation of glycosylated hemoglobin (HbA1c) levels with histological characters of atherosclerotic plaque that makes it vulnerable, as well as ultrasound (US) criteria that can contribute to the prognosis of carotid disease.

MATERIAL AND METHODS

This is a single-center prospective study. Our study population consists of 74 diabetic and nondiabetic patients with carotid atherosclerosis who underwent carotid endarterectomy in our department. Patient categorization was based on the following criteria: levels of HbA1c, gender, and risk factors (smoking, hypertension), carotid stenosis rate, symptomatic or asymptomatic carotid disease, histological examination of the atherosclerotic plaque, and US morphological criteria of the plaque.

RESULTS

The mean age of the patients was 68.2 years (standard deviation = 7.8); 58.1% were smokers, 71.6% had arterial hypertension, 37.8% had symptomatic carotid disease, and 64.9% had atherosclerotic plaque type 6. Futhermore, 95.9% of the patients had a carotid stenosis rate more than 70% and 4.1% had from 50% to 69%. Older patients had more frequent type 7 and 8 atherosclerotic plaque based on American Heart Association scoring system than younger patients (P = 0.041). The relative likelihood of atherosclerotic plaque type 7 and 8 was 1.12 times higher in older patients (Odds ratio [OR] = 1.12, P = 0.029). Patients with higher levels of HbA1cwere more likely to have type 6 atherosclerotic plaque than those with atherosclerotic lesions type 7 and 8 (P < 0.001). Specifically, increasing the level of HbA1c by 1 mg/dl increases the likelihood of the presence of vulnerable plaque by 2.55%. Moreover, the relative likelihood of a type 6 atherosclerotic plaque was 10.4 times higher in the older patients (OR = 10.4, P < 0.001).

CONCLUSIONS

This study demonstrates that levels of HbA1c and advanced age are 2 factors that may be correlated with the presence of vulnerable carotid plaques in diabetic population. Moreover, HbA1c is an independent factor that could possibly be used as a prognostic marker for carotid artery disease, although further studies are needed to explore this association to elucidate the precise role of HbA1c.

Relationship Between Glycated Haemoglobin and Carotid Atherosclerotic Disease Among Patients with Acute Ischaemic Stroke

Objectives

This study aimed to determine the relationship between glycaemic control and carotid atherosclerotic disease among patients with acute ischaemic stroke (AIS).

Methods

This retrospective cross-sectional study took place in the Neurology Department of King Fahad Hospital of University, Khobar, Saudi Arabia, from April to October 2017. Data were collected from the medical records of 244 patients with a diagnosis of AIS confirmed by computed tomography. Doppler ultrasounds of the carotid artery were performed to determine the presence of increased carotid intima media thickness (CIMT) and plaques.

Results

Significantly higher mean glycated haemoglobin (HbA1c) levels were noted in cases with high CIMT values (P = 0.002), but not in cases with carotid plaques (P = 0.360). In addition, there was a significant association between diabetes mellitus (DM) and high CIMT (P = 0.045), but not with carotid plaques (P = 0.075). Finally, while dyslipidaemia and age were independently correlated with high CIMT values (P = 0.034 and <0.001, respectively) and carotid plaques (P <0.001 each), no independent relationships were noted in terms of gender and other risk factors like DM, hypertension and smoking (P >0.050 each).

Conclusion

High HbA1c levels were associated with high CIMT values, but not with carotid plaques. Therefore, HbA1c levels may be useful as an indirect marker of the initial stages of carotid artery atherosclerosis.

Echolucency-based phenotype in carotid atherosclerosis disease for risk stratification of diabetes patients

AIM

The study investigated the association of carotid ultrasound echolucent plaque-based biomarker with HbA1c, measured as age-adjusted grayscale median (AAGSM) as a function of chronological age, total plaque area, and conventional grayscale median (GSM_conv).

METHODS

Two stages were developed: (a) automated measurement of carotid parameters such as total plaque area (TPA); (b) computing the AAGSM as a function of GSM_conv, age, and TPA. Intra-operator (novice and experienced) analysis was conducted.

RESULTS

IRB approved, 204 patients' left/right CCA (408 images) ultrasound scans were collected: mean age: 69 ± 11 years; mean HbA1c: 6.12 ± 1.47%. A moderate inverse correlation was observed between AAGSM and HbA1c (CC of -0.13, P = 0.01), compared to GSM (CC of -0.06, P = 0.24). The RCCA and LCCA showed CC of -0.18, P < 0.01 and -0.08; P < 0.24. Female and males showed CC of -0.29, P < 0.01 and -0.10, P = 0.09. Using the threshold for AAGSM and HbA1c as: low-risk (AAGSM > 100; HbA1c < 5.7%), moderate-risk (40 < AAGSM < 100; 5.7% < HbA1c < 6.5%) and high-risk (AAGSM < 40; HbA1c > 6.5%), the area under the curve showed a better performance of AAGSM over GSM_conv. A paired t-test between operators and expert (P < 0.0001); inter-operator CC of 0.85 (P < 0.0001).

CONCLUSIONS

Echolucent plaque in patients with diabetes can be more accurately characterized for risk stratification using AAGSM compared to GSM_conv.

Factors associated with carotid Intima media thickness and carotid plaque score in community-dwelling and non-diabetic individuals

Background

The carotid intima media thickness (cIMT) and carotid plaque score (cPS) are respective markers of early and late stage subclinical atherosclerosis. Relationships between some laboratory parameters and subclinical atherosclerosis are not yet clear in community dwelling individuals and non-diabetic subjects, so we try to elucidate these relationships and find a model to predict early and late stage subclinical atherosclerosis.

Methods

We examined relationships of the cIMT and cPS with different laboratory and demographic data of 331 subjects from a community-based prospective cohort study, using univariate and multivariate analyses.

Results

In regression models and after multiple adjustments, only systolic blood pressure (SBP), age, glycated hemoglobin (HBA1c), and waist circumference (WC) were determinants of the cIMT, and only age, SBP, HBA1c, and blood urea nitrogen (BUN) were determinants of a cPS of > 2 in all individuals. Only HBA1c lost its association with regard to predicting the cIMT in non-diabetic subjects.

Conclusions

HBA1c at > 5.9% can determine early and late stage subclinical atherosclerosis in community dwelling individuals, but only late stage subclinical atherosclerosis in non-diabetic subjects.

Association between HbA1c and carotid atherosclerosis among elderly Koreans with normal fasting glucose

Aim

We examined whether glycated haemoglobin (HbA1c) is associated to carotid atherosclerosis in an elderly Korean population with normal fasting glucose.

Methods

Using data from the Korean Urban Rural Elderly study, we conducted a cross-sectional analysis of 1,133 participants (335 men and 798 women) with a mean age of 71.8 years. All participants had fasting blood glucose less than 100mg/dL (5.6 mmol/L) and HbA1c level below 6.5% (48 mmol/mol). They were also free from a history of cardiovascular disease, known type 2 diabetes mellitus or use of anti-diabetes medications. Carotid atherosclerosis was assessed by intima-media thickness (IMT) using ultrasonography. The association between HbA1c and carotid IMT was investigated using multivariable linear regression analysis.

Results

HbA1c levels were independently and positively associated with carotid IMT (β = 0.020, p = 0.045) after adjusting for sex, age, body mass index, systolic blood pressure, diastolic blood pressure, triglyceride, LDL cholesterol, smoking and alcohol intake. However, fasting insulin and glucose levels were not associated with carotid IMT.

Conclusion

HbA1c levels were positively associated with carotid atherosclerosis, as assessed by carotid IMT, in an elderly population with normoglycemia. Our study suggested that higher HbA1c level is an effective and informative marker of carotid atherosclerosis in an elderly population.

Update on pre-diabetes: Focus on diagnostic criteria and cardiovascular risk

Pre-diabetes, which is typically defined as blood glucose concentrations higher than normal but lower than the diabetes threshold, is a high-risk state for diabetes and cardiovascular disease development. As such, it represents three groups of individuals: Those with impaired fasting glucose (IFG), those with impaired glucose tolerance (IGT) and those with a glycated haemoglobin (HbA_1c) between 39-46 mmol/mol. Several clinical trials have shown the important role of IFG, IGT and HbA_1c-pre-diabetes as predictive tools for the risk of developing type 2 diabetes. Moreover, with regard to cardiovascular disease, pre-diabetes is associated with more advanced vascular damage compared with normoglycaemia, independently of confounding factors. In view of these observations, diagnosis of pre-diabetes is mandatory to prevent or delay the development of the disease and its complications; however, a number of previous studies reported that the concordance between pre-diabetes diagnoses made by IFG, IGT or HbA_1c is scarce and there are conflicting data as to which of these methods best predicts cardiovascular disease. This review highlights recent studies and current controversies in the field. In consideration of the expected increased use of HbA_1c as a screening tool to identify individuals with alteration of glycaemic homeostasis, we focused on the evidence regarding the ability of HbA_1c as a diagnostic tool for pre-diabetes and as a useful marker in identifying patients who have an increased risk for cardiovascular disease. Finally, we reviewed the current evidence regarding non-traditional glycaemic biomarkers and their use as alternatives to or additions to traditional ones.

Elevated hemoglobin A1c Is Associated with Carotid Plaque Vulnerability: Novel Findings from Magnetic Resonance Imaging Study in Hypertensive Stroke Patients

The association between hemoglobin A1c (HbA1c) level and carotid plaque vulnerability has been rarely studied by magnetic resonance imaging (MRI). The present study of MRI-identified carotid atherosclerotic lesions in hypertensive patients with acute stroke therefore sought to determine the associations between HbA1c level and plaque morphological and compositional characteristics and acute cerebral infarction (ACI) severity. Eighty hypertensive patients with acute stroke were enrolled; stratified into high (≥6.5%) and low (<6.5%) HbA1c groups; and underwent carotid and brain MRI to assess carotid plaque features and ACI volume in the region supplied by the internal carotid artery (ICA) in the symptomatic side. Plaque burden [percent wall volume (PWV), max wall thickness (max-WT)] and lipid-rich necrotic core (LRNC) were larger in the high as compared to the low HbA1c group. High HbA1c was an independent risk factor for the presence of plaque (odds ratio [OR] = 3.71) and LRNC plaque (OR = 7.08). HbA1c independently correlated with ACI severity among patients with ICA region cerebral infarction and carotid plaque. Our study suggested that an elevated HbA1c may have an adverse effect on carotid plaque vulnerability especially those with larger LRNC volumes in hypertensive stroke patients, which might exacerbate the severity of ACIs.

Distribution of Glycated Haemoglobin According to Early-Life and Contemporary Characteristics in Adolescents and Adults without Diabetes: The 1982 and 1993 Pelotas Birth Cohorts

Aim

Glycated haemoglobin (HbA_1c), a marker of glucose control in individuals with diabetes mellitus, is also related with the incidence of cardiometabolic risk in populations free of disease. The aim of this study was to describe the distribution of HbA_1c levels according to early-life and contemporary factors in adolescents and adults without diabetes mellitus.

Methods

HbA_1c was measured in adults aged 30 years and adolescents aged 18 years who are participants in the 1982 and 1993 Pelotas Birth Cohorts, respectively. Bivariate and multivariate analyses were performed to describe the HbA_1c mean values according to early-life and contemporary characteristics collected prospectively since birth.

Results

The distribution of the HbA_1c was approximately normal in both cohorts, with a mean (SD) 5.10% (0.43) in the 1982 cohort, and 4.89% (0.50) in the 1993 cohort. HbA_1c mean levels were significantly higher in individuals self-reported as black/brown skin color compared to those self-reported as white in both cohorts. Parental history of diabetes was associated with higher HbA_1c mean in adults, while stunting at one year old presented an inverse relation with the outcome in adolescents. No other early and contemporary factors were associated with HbA_1c levels in adults or adolescents.

Conclusions

We found a consistent relationship between HbA_1c and skin color in both cohorts. Further research is needed to understand the role of genomic ancestry on levels of HbA_1c concentrations which may inform policies and preventive actions for diabetes mellitus and cardiometabolic risk.

Serum chemerin and high-sensitivity C reactive protein as markers of subclinical atherosclerosis in Egyptian patients with type 2 diabetes

CONTEXT

Chemerin is one of the adipokines that regulate fat metabolism. High-sensitivity C-reactive protein (hs-CRP) may be considered as a cardiovascular risk predictor. Measuring intima-media thickness of the CCA (C-IMT) is a well-evidenced tool for the detection of early stages of atherosclerosis. We aimed here to study both serum chemerin and hs-CRP as markers of subclinical atherosclerosis in Egyptian patients with type 2 diabetes, who are angiographically free of coronary artery disease (CAD).

SUBJECTS AND METHODS

This cross-sectional study was conducted on 180 subjects divided into two groups: Group A included 90 type 2 diabetic patients without CAD and group B including 90 nondiabetic control subjects. All study subjects were having normal coronary angiography. Serum chemerin, homeostasis model assessment for insulin resistance (HOMA-IR), glycated haemoglobin (HbA1c), lipid profile, hs-CRP as well as C-IMT were assessed in all study subjects.

RESULTS

There was a statistically significant difference between the 2 groups regarding serum chemerin level, HOMA-IR, hs-CRP and C-IMT; being higher in the diabetic patients than in the control group (p = 0.006, 0.024, 0.040 and <0.001, respectively). There was positive correlation between serum chemerin level and waist-to-hip ratio (WHR), HOMA-IR, hs-CRP and C-IMT. Carotid intima-media thickness was positively correlated with patients' WHR, blood pressure, HbA1c, diabetes duration as well as hs-CRP, and negatively correlated with ankle-brachial index (ABI). Linear regression analysis showed that HbA1c, serum chemerin and hs-CRP were independently affecting C-IMT. Serum hs-CRP was positively correlated with HbA1c and HOMA-IR (p = 0.006 and 0.032, respectively), and negatively correlated with HDL-cholesterol level (p = 0.018).

CONCLUSION

Both serum chemerin and hs-CRP could be considered as markers of subclinical atherosclerosis, and hence, may be utilized for the early detection of macrovascular disease, in Egyptian patients with type 2 diabetes.

HbA1c is significantly associated with arterial stiffness but not with carotid atherosclerosis in a community-based population without type 2 diabetes: The Dong-gu study

OBJECTIVES

We examined the associations between HbA1c levels and various atherosclerotic vascular parameters among adults without diabetes from the general population.

METHODS

A total of 6500 community-dwelling adults, who were free of type 2 diabetes and ≥50 years of age, were included. High-resolution B-mode ultrasound was used to evaluate carotid artery structure, including intima-media thickness (IMT), plaque, and luminal diameter. Brachial-ankle pulse wave velocity (baPWV), which is a useful indicator of systemic arterial stiffness, was determined using an automatic waveform analysis device.

RESULTS

No significant associations were observed between HbA1c, carotid IMT, plaque, or luminal diameter in a fully adjusted model. However, the odds ratio (95% confidence interval) for high baPWV (defined as the highest quartile) increased by 1.43 (1.19-1.71) per 1% HbA1c increase after adjusting for conventional risk factors in a multivariate logistic regression analysis. In addition, HbA1c was independently associated with baPWV in a multivariate linear regression analysis.

CONCLUSIONS

High-normal HbA1c level was independently associated with arterial stiffness, but not with carotid atherosclerotic parameters, in the general population without diabetes. Our results suggest that the functional atherosclerotic process may already be accelerated according to HbA1c level, even at a level below the diagnostic threshold for diabetes.

Ultrasound and Biochemical Diagnostic Tools for the Characterization of Vulnerable Carotid Atherosclerotic Plaque

Stroke is a leading cause of morbidity and mortality worldwide, and characterization of vulnerable carotid plaque remains the spearhead of scientific research. Plaque destabilization, the key factor that induces the series of events leading to the clinical symptoms of carotid artery disease, is a consequence of complex mechanical, structural and biochemical processes. Novel imaging and molecular markers have been studied as predictors of disease outcome with promising results. The aim of this review is to present the current state of research on the association between ultrasound-derived echogenicity indices and blood parameters indicative of carotid plaque stability and activity. Bibliographic research revealed that there are limited available data. Among the biomarkers studied, those related to oxidative stress, lipoproteins and diabetes/insulin resistance are associated with echolucent plaques, whereas adipokines are associated with echogenic plaques. Biomarkers of inflammation and coagulation have not exhibited any conclusive relationship with plaque echogenicity, and it is not possible to come to any conclusion regarding calcification-, apoptosis- and neo-angiogenesis-related parameters because of the extremely limited bibliographic data.

Mechanisms of ectopic calcification: implications for diabetic vasculopathy

Vascular calcification (VC) is the deposition of calcium/phosphate in the vasculature, which portends a worse clinical outcome and predicts major adverse cardiovascular events. VC is an active process initiated and regulated via a variety of molecular signalling pathways. There are mainly two types of calcifications: the media VC and the intima VC. All major risk factors for cardiovascular disease (CVD) have been linked to the presence/development of VC. Besides the risk factors, a genetic component is also operative to determine arterial calcification. Several events take place before VC is established, including inflammation, trans-differentiation of vascular cells and homing of circulating pro-calcific cells. Diabetes is an important predisposing factor for VC. Compared with non-diabetic subjects, patients with diabetes show increased VC and higher expression of bone-related proteins in the medial layer of the vessels. In this review we will highlight the mechanisms underlying vascular calcification in diabetic patients.

Association of hemoglobin A1c and glycated albumin with carotid atherosclerosis in community-dwelling Japanese subjects: the Hisayama Study

Background

It is not clear which glucose measure is more useful in the assessment of atherosclerosis. We investigated the associations of hemoglobin A_1c (HbA_1c), glycated albumin (GA), 1,5-anhydroglucitol (1,5-AG), fasting plasma glucose (FPG), and 2-hour postload glucose (PG) with carotid intima-media thickness (IMT) in community-dwelling Japanese subjects.

Methods

A total of 2702 subjects aged 40–79 years underwent a 75-g oral glucose tolerance test and measurements of HbA_1c, GA, 1,5-AG, and carotid IMT by ultrasonography in 2007–2008. Carotid wall thickening was defined as a maximum IMT of >1.0 mm. The crude and multivariable-adjusted linear and logistic regression models were used to analyze cross-sectional associations between levels of glycemic measures and carotid IMT.

Results

The crude average of the maximum IMT increased significantly with rising quartiles of HbA_1c, GA, FPG, and 2-hour PG levels in subjects with and without glucose intolerance (GI), while no clear association was observed for 1,5-AG. After adjustment for other confounding factors, positive trends for HbA_1c, GA, and FPG (all p for trend < 0.05), but not 2-hour PG (p = 0.07) remained robust in subjects with GI, but no such associations were found in those without GI. When estimating multivariable-adjusted β values for the associations of 1 SD change in glycemic measures with the maximum IMT in subjects with GI, the magnitude of the influence of HbA_1c (β = 0.021), GA (β = 0.024), and FPG (β = 0.024) was larger than that of 2-hour PG (β = 0.014) and 1,5-AG (β = 0.003). The multivariable-adjusted odds ratios for the presence of carotid wall thickening increased significantly with elevating HbA_1c, GA, and FPG levels only in subjects with GI (all p for trend < 0.001). Among subjects with GI, the area under the receiver operating characteristic curve significantly increased by adding HbA_1c (p = 0.04) or GA (p = 0.04), but not 1,5-AG, FPG, or 2-hour PG, to the model including other cardiovascular risk factors.

Conclusions

In community-dwelling Japanese subjects with GI, elevated HbA_1c, GA, and FPG levels were significantly associated with increased carotid IMT, and HbA_1c and GA provided superior discrimination for carotid wall thickening compared to 1,5-AG, FPG, and 2-hour PG, suggesting that HbA_1c and GA are useful for assessing carotid atherosclerosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0247-7) contains supplementary material, which is available to authorized users.

Hemoglobin a1c and the progression of coronary artery calcification among adults without diabetes

OBJECTIVE

Higher levels of hemoglobin A1c (HbA1c) are associated with increased cardiovascular disease risk among individuals without diabetes and may also be positively associated with coronary artery calcification (CAC). This study investigated the association of HbA1c with CAC progression in the Coronary Artery Risk Development in Young Adults study.

RESEARCH DESIGN AND METHODS

We included 2,076 participants with HbA1c and noncontrast computed tomography (CT) assessed at baseline (2005-2006), and CT repeated 5 years later (2010-2011). CAC progression was defined as 1) incident CAC (increase >0 Agatston units among those with no CAC at baseline), 2) any CAC progression (increase >10 Agatston units between examinations), and 3) advanced CAC progression (increase >100 Agatston units between examinations).

RESULTS

During the 5-year follow-up period, 12.9% of participants without baseline CAC developed incident CAC; among all participants, 18.2% had any CAC progression and 5.4% had advanced CAC progression. Higher HbA1c was associated with incident CAC (risk ratio [RR] = 1.45; 95% CI 1.02, 2.06), any CAC progression (RR = 1.51; 95% CI 1.16, 1.96), and advanced CAC progression (RR = 2.42; 95% CI 1.47, 3.99) after adjustment for sociodemographic factors. Additional adjustment for cardiovascular risk factors attenuated the associations of HbA1c with incident CAC (RR = 1.05; 95% CI 0.74, 1.49) and any CAC progression (RR = 1.13; 95% CI 0.87, 1.47). In contrast, the association of HbA1c with advanced CAC progression persisted in multivariable adjusted models (RR = 1.78; 95% CI 1.08, 2.95).

CONCLUSIONS

Higher HbA1c was independently associated with advanced CAC progression among individuals without diabetes, while the associations with incident CAC and any CAC progression were accounted for by other established cardiovascular risk factors.

Cardiovascular and lung function in relation to outdoor and indoor exposure to fine and ultrafine particulate matter in middle-aged subjects

This cross-sectional study investigated the relationship between exposure to airborne indoor and outdoor particulate matter (PM) and cardiovascular and respiratory health in a population-based sample of 58 residences in Copenhagen, Denmark. Over a 2-day period indoor particle number concentrations (PNC, 10-300 nm) and PM2.5 (aerodynamic diameter<2.5 μm) were monitored for each of the residences in the living room, and outdoor PNC (10-280 nm), PM2.5 and PM10 (aerodynamic diameter<10 μm) were monitored at an urban background station in Copenhagen. In the morning, after the 2-day monitoring period, we measured microvascular function (MVF) and lung function and collected blood samples for biomarkers related to inflammation, in 78 middle-aged residents. Bacteria, endotoxin and fungi were analyzed in material from electrostatic dust fall collectors placed in the residences for 4 weeks. Data were analyzed using linear regression with the generalized estimating equation approach. Statistically significant associations were found between indoor PNC, dominated by indoor use of candles, and lower lung function, the prediabetic marker HbA1c and systemic inflammatory markers observed as changes in leukocyte differential count and expression of adhesion markers on monocytes, whereas C-reactive protein was significantly associated with indoor PM2.5. The presence of indoor endotoxin was associated with lower lung function and expression of adhesion markers on monocytes. An inverse association between outdoor PNC and MVF was also statistically significant. The study suggests that PNC in the outdoor environment may be associated with decreased MVF, while PNC, mainly driven by candle burning, and bioaerosols in the indoor environment may have a negative effect on lung function and markers of systemic inflammation and diabetes.

Subchronic effects of inhaled ambient particulate matter on glucose homeostasis and target organ damage in a type 1 diabetic rat model

Epidemiological studies have reported associations between particulate matter (PM) and cardiovascular effects, and diabetes mellitus (DM) patients might be susceptible to these effects. The chief chronic injuries resulting from DM are small vascular injuries (micro-vascular complications) or large blood vessel injuries (macro-vascular complications). However, toxicological data regarding the effects of PM on DM-related cardiovascular complications is limited. Our objective was to investigate whether subchronic PM exposure alters glucose homeostasis and causes cardiovascular complications in a type 1 DM rat model. We constructed a real world PM2.5 exposure system, the Taipei Air Pollution Exposure System for Health Effects (TAPES), to continuously deliver non-concentrated PM for subchronic exposure. A type 1 DM rat model was induced using streptozotocin. Between December 22, 2009 and April 9, 2010, DM rats were exposed to PM or to filtered air (FA) using TAPES in Taipei, Taiwan, 24h/day, 7days/week, for a total of 16weeks. The average concentrations (mean [SD]) of PM2.5 in the exposure and control chambers of the TAPES were 13.30 [8.65] and 0.13 [0.05]μg/m(3), respectively. Glycated hemoglobin A1c (HbA1c) was significantly elevated after exposure to PM compared with exposure to FA (mean [SD], 7.7% [3.1%] vs. 4.7% [1.0%], P<0.05). Interleukin 6 and fibrinogen levels were significantly increased after PM exposure. PM caused focal myocarditis, aortic medial thickness, advanced glomerulosclerosis, and accentuation of tubular damage of the kidney (tubular damage index: 1.76 [0.77] vs. 1.15 [0.36], P<0.001). PM exposure might induce the macro- and micro-vascular complications in DM through chronic hyperglycemia and systemic inflammation.

Serum parathyroid hormone as a potential novel biomarker of coronary heart disease

OBJECTIVE

This study aimed to evaluate the relationships between serum parathyroid hormone (PTH) and coronary heart disease (CHD).

METHODS

From July 2011 to February 2013, a total of 79 CHD patients and 94 normal control patients with ages ranging from 25 to 79 years were included in this study. Serum PTH level and common risk factors of CHD (age, gender, cholesterol, glycosylated hemoglobin [HbA1c], blood pressure [BP], history of diabetes, smoking, and body mass index) were investigated. Pearson's correlation and multiple regression analyses were used to evaluate the relationships between serum PTH level and CHD risk factors. All statistical analyses were performed using the SPSS 18.0 software.

RESULTS

RESULTS from Pearson's correlation analysis indicated that age, systolic blood pressure (SBP), diastolic blood pressure (DBP), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), HbA1c, history of smoking, and serum PTH level were risk factors for CHD (all p<0.05). Serum PTH levels were positively correlated with DBP (r=0.256, p=0.010) and HbA1c (r=0.223, p=0.003), while not being related to other risk factors of CHD (all p>0.05). Multiple linear regression analysis showed that SBP, DBP, LDL-c, and HDL-c may be important determinants of CHD (all p<0.05). Further, serum PTH level is also an independent risk factor for CHD (p<0.001).

CONCLUSION

Our results provide evidence that serum PTH level may be involved in the pathogenesis of CHD. Thus, PTH could be used as an important biomarker in the diagnosis of CHD.

Early and current physical activity: relationship with intima-media thickness and metabolic variables in adulthood

BACKGROUND

It is unclear whether early physical activity has a greater influence on intima-media thickness and metabolic variables than current physical activity.

OBJECTIVE

To analyze the relationship between current and early physical activity, metabolic variables, and intima-media thickness measures in adults.

METHOD

The sample was composed of 55 healthy subjects of both sexes (33 men and 22 women). Total body fat and trunk fat were estimated by dual-energy X-ray absorptiometry. Carotid and femoral intima-media thickness were measured using a Doppler ultrasound device. A 12-hour fasting blood sample collection was taken (fasting glucose and lipid profile). Early physical activity was assessed through face-to-face interview, and the current physical activity was assessed by pedometer (Digi-Walker Yamax, SW200), which was used for a period of seven days.

RESULTS

Current physical activity was negatively related to total cholesterol (rho=-0.31), while early physical activity was negatively related to triglycerides (rho=-0.42), total cholesterol (rho=-0.28), very low density lipoprotein (rho=-0.44), and carotid intima-media thickness (rho=-0.50). In the multivariate model, subjects engaged in sports activities during early life had lower values of very low density lipoprotein (b=-8.74 [b95%CI=-16.1; -1.47]) and carotid intima-media thickness (b=-0.17 [95%CI: -0.28; -0.05]).

CONCLUSION

Early 95%CI physical activity has a significant influence on carotid intima-media thickness, regardless of the current physical activity.

Hemoglobin A(1c) in nondiabetic patients: an independent predictor of coronary artery disease and its severity

OBJECTIVE

To examine the association between hemoglobin A(1c) (HbA(1c)) and the presence, severity, and complexity of angiographically proven coronary artery disease (CAD) in nondiabetic patients.

PATIENTS AND METHODS

We performed a single-center, observational, cross-sectional study of 1141 consecutive nondiabetic patients who underwent coronary angiography from January 1, 2011, through December 31, 2011. The study population was divided into 4 interquartiles according to HbA(1c) levels (<5.5%, 5.5%-5.7%, 5.8%-6.1%, and >6.1%).

RESULTS

Patients with higher HbA(1c) levels tended to be older, overweight, and hypertensive, had higher blood glucose levels, and had lower glomerular filtration rates. Higher HbA(1c) levels were associated in a graded fashion with the presence of CAD, disease severity (higher number of diseased vessels and presence of left main and/or triple vessel disease), and disease complexity (higher SYNTAX score, higher number of patients in intermediate or high SYNTAX tertiles, coronary calcium, and chronic total occlusions). After adjustment for major conventional cardiovascular risk factors, compared with patients with HbA(1c) levels less than 5.5%, the odds ratios of occurrence of CAD in the HbA(1c) quartiles of 5.5% to 5.7%, 5.8% to 6.1%, and greater than 6.1% were 1.8 (95% CI, 1.2-2.7), 3.5 (95% CI, 2.3-5.3), and 4.9 (95% CI, 3.0-8.1), respectively.

CONCLUSION

The HbA(1c) level has a linear incremental association with CAD in nondiabetic individuals. The HbA(1c) level is also independently correlated with disease severity and higher SYNTAX scores. Thus, HbA(1c) measurement could be used to improve cardiovascular risk assessment in nondiabetic individuals.

The negative effects of obesity and poor glycemic control on cognitive function: a proposed model for possible mechanisms

Obesity has reached epidemic proportions and is a contributor to many adverse health outcomes, including increased risk for dementia and adverse structural and functional brain changes. Milder forms of cognitive impairment in multiple domains can also be found in obese individuals of all ages that are believed to stem from brain abnormalities long prior to onset of neurologic conditions such as dementia. However, the mechanisms for adverse brain changes and subsequent cognitive dysfunction in obesity are complex and poorly understood. This paper proposes a possible etiologic model for obesity associated cognitive impairment with emphasis on the role of poor glycemic control and conditions like type 2 diabetes mellitus. Clinical implications associated with treatment of obesity in persons with cognitive deficits in addition to the cognitive promoting effects of weight loss surgery are also discussed.

Relationship between glycated haemoglobin and subclinical atherosclerosis in obese children and adolescents

OBJECTIVE

To explore the relationship between glycated haemoglobin A1C (HbA1C) and subclinical atherosclerosis as assessed by carotid intima-media thickness (cIMT) in Chinese Han obese children and adolescents without diabetes.

METHODS

A total of 524 obese children and adolescents without diabetes were analysed. All participants underwent HbA1C measurements, oral glucose tolerance tests and ultrasound measurements of cIMT. The logistic regression models were implemented to evaluate the adjusted OR of HbA1C for increased cIMT.

RESULTS

In obese boys, HbA1C was associated with increased cIMT independently of age, measurements of anthropometry, blood pressure, plasma lipid and lipoprotein, fasting plasma glucose, 2 h postchallenge glucose, uric acid and hepatic function. After adjustment for all these risk factors, the OR of increased cIMT for every 1% (11 mmol/mol) increase in HbA1C was 2.702 (95% CI 1.640 to 4.452). However, in girls, the major risk factor independently associated with cIMT was measurement of abdominal obesity instead of HbA1C.

CONCLUSIONS

Our research suggests that the adoption of HbA1C as a diagnostic criterion of prediabetes and diabetes in obese boys may help to identify early macrovascular complications.

Association of glycated hemoglobin with carotid intimal medial thickness in Asian Indians with normal glucose tolerance

AIM

To assess the association of glycated hemoglobin (HbA1c) levels with carotid intimal medial thickness (CIMT) in Asian Indians with normal glucose tolerance (NGT).

METHODS

Subjects with NGT were recruited from the Chennai Urban Rural Epidemiology Study carried out on a representative population of Chennai, South India. All subjects had fasting plasma glucose <100 mg/dl (5.6 mmol/l) and 2-h post load plasma glucose <140 mg/dl (7.8 mmol/l). HbA1c was measured using the Biorad Variant machine. CIMT was measured on the right common carotid artery using high-resolution B-mode ultrasonography.

RESULTS

The study group included 1383 NGT subjects, of whom 760 (54.9%) were women. The mean CIMT value in the 1st quartile of HbA1c (<5.2%) was 0.65 and it increased significantly to 0.73 in the last quartile of HbA1c (>5.8) (p<0.001). Regression analysis showed that HbA1c had a strong association with CIMT after adjusting for age, gender, waist circumference, systolic and diastolic blood pressure, LDL cholesterol, serum triglycerides, HOMA-IR and smoking (ß - 0.046, p=0.047).

CONCLUSION

Even among subjects with NGT, there is a significant increase in CIMT with increasing levels of HbA1c, showing the value of using HbA1c for diagnosis of glucose intolerance.

Changes in glycemic control are associated with changes in cognition in non-diabetic elderly

The aim of the present study was to examine the relationship of changes in long term glucose levels as measured by Hemoglobin A1c (HbA1c) with simultaneous changes in cognition. The sample included in the present analysis consisted of 101 community dwelling non-diabetic elderly subjects participating in ongoing longitudinal studies of cognition. Subjects were included in this study if they were cognitively normal at baseline, had at least one co-temporaneous follow-up assessment of HbA1c and the Mini Mental State Exam (MMSE), and complete data on age, gender, race, and years of education. MMSE decline over time was the main outcome measure. In TOBIT mixed regression models, MMSE was the dependent variable and HbA1c the time-varying covariate. Sociodemographic (age, gender, and education), cardiovascular (hypertension and APOE4 status), and lifestyle (smoking and physical activity) covariates were included in the statistical model. After adjusting for age at follow-up, there was a decrease of 1.37 points in the MMSE (p = 0.0002) per unit increase in HbA1c. This result remained essentially unchanged after adjusting also for gender and education (p = 0.0005), cardiovascular factors (p = 0.0003), and lifestyle (p = 0.0006). Additionally, results remained very similar after excluding subjects with potentially incipient diabetes with HbA1c between 6 and 7. These findings suggest that in non-diabetic non-demented elderly subjects, an increase in HbA1c over time is associated with cognitive decline. Such results may have broad clinical applicability since manipulation of glucose control, even in non-diabetics, may affect cognitive performance, perhaps enabling preventive measures against dementia.

Obstructive sleep apnea increases hemoglobin A1c levels regardless of glucose tolerance status

OBJECTIVE

We sought to clarify the association between the severity of obstructive sleep apnea (OSA) and hemoglobin A1c (HbA1c) levels.

METHODS

HbA1c levels were measured in 330 subjects who were suspected of having OSA and who underwent polysomnography. A 75-g oral glucose tolerance test was performed in 308 subjects who had not been diagnosed to have diabetes mellitus. Patients with use of hypoglycemic agents were excluded. The 330 subjects were divided into three subgroups: 164 with normal glucose tolerance, 111 with impaired glucose tolerance, and 55 with diabetes mellitus (DM).

RESULTS

Univariate regression analyses showed that natural logarithm(Ln)age, Lnbody mass index, hypertension, DM, Lnapnea-hypopnea index, Lnarousal index, and Lnlowest arterial oxyhemoglobin saturation (L-SpO(2)) were associated with LnHbA1c. A multiple regression analysis showed that Lnage (β=0.16, P=0.003), DM (β=0.39, P<0.001), and Ln L-SpO(2) (β=-0.29, P<0.001) were associated with LnHbA1c. Subgroup analyses showed that Ln L-SpO(2) was independently associated with LnHbA1c in each subgroup.

CONCLUSIONS

L-SpO(2) was independently associated with HbA1c regardless of the glucose tolerance status. This suggests that OSA-induced hypoxia could increase an individual's average blood glucose level.

Hemoglobin A1c as a diagnostic tool: public health implications from an actor-network perspective

Public health arguments for collecting hemoglobin A1c (HbA1c) data, particularly in clinical settings, should be reframed to place more emphasis on nonmedical determinants of population health. We compare individual- with population-level interpretations of HbA1c titers. This comparison reveals that public health researchers need to pay close attention to diagnostic tests and their uses, including rhetorical uses. We also synthesize historical and current evidence to map out 2 possible scenarios for the future. In the first scenario, prevention efforts emphasize primary care and focus almost entirely downstream. The second scenario anticipates downstream interventions but also upstream interventions targeting environments. Our analysis adapts actor-network theory to strategic planning and forecasting in public health.

Smoking is a strong risk factor for non-vertebral fractures in women with diabetes: the Tromsø Study

In this longitudinal study of 4,160 postmenopausal women (3,947 without and 213 with self-reported diabetes), smoking was strongly related to fracture risk in those with diabetes.

INTRODUCTION

Smoking is related to low bone mass and increased risk of fracture risk in postmenopausal women of the general population. The aim of the present longitudinal population-based study was to examine the effect of smoking on the risk of non-vertebral fractures in women ≥ 55 years of age, with specific focus on its relationship with diabetes.

METHODS

A total of 4,160 women (3,947 without and 213 with self-reported diabetes) from the municipality of Tromsø, Norway, were followed for a mean of 7.6 years. Measurements of height and weight and questionnaire information concerning smoking and alcohol consumption habits, physical activity, prevalent diseases, and use of medication were collected before the start of follow-up. Non-vertebral fractures were registered during follow-up.

RESULTS

A total of 1,015 without and 66 with diabetes sustained a new non-vertebral fracture. Smoking status (never, past, and current) was significantly associated with an increased risk of fracture both in women with and without diabetes (p values for trend 0.02 and <0.001, respectively, after adjustments for age), but in women without diabetes, the relationship was no longer significant after multiple adjustments. There was a strong interaction between smoking status and diabetes on fracture risk (p= 0.004). Women with diabetes who were current smokers had a 3.47 (95% CI 1.82-6.62) higher risk of non-vertebral fractures than diabetic women who were never smokers (p value for linear trend = 0.001, after multiple adjustments).

CONCLUSION

We conclude that smoking is strongly related to fracture risk in postmenopausal women with self-reported diabetes.

Association between hemoglobin A1c, carotid atherosclerosis, arterial stiffness, and peripheral arterial disease in Korean type 2 diabetic patients

AIMS

To evaluate the association between hemoglobin A(1c) (HbA(1c)), carotid atherosclerosis, arterial stiffness, and peripheral arterial disease (PAD) in Korean type 2 diabetic patients.

METHODS

A total of 370 type 2 diabetic patients registered with the public health center in Gokseng-gun, Korea, participated in this study. Following an overnight fast, venous blood was collected and analyzed by high-performance liquid chromatography. The carotid intima-media thickness (IMT), amount of carotid plaque, brachial ankle pulse wave velocity (baPWV), and ankle-brachial index (ABI) of each patient were also assessed.

RESULTS

For categorical variables, we performed logistic regression after adjustment for other CVD risk factors. There was a significant association between HbA(1c) and carotid plaque [OR 2.66, 95% confidence interval (CI) 1.01 to 5.67 for the highest vs. the lowest tertile of HbA(1c)], and PAD (OR 3.75, 95% CI 1.30 to 10.81). For continuous variables, we performed analysis of covariance (ANCOVA) after adjustment for other covariates. The mean values of common carotid artery intima-media thickness (CCA-IMT) and baPWV were not significantly different according to the HbA(1c) tertiles.

CONCLUSION

HbA(1c) was significantly associated with carotid plaque and PAD, but not CCA-IMT and baPWV in Korean type 2 diabetic patients.

Deleterious effects of reactive aldehydes and glycated proteins on macrophage proteasomal function: possible links between diabetes and atherosclerosis

People with diabetes experience chronic hyperglycemia and are at a high risk of developing atherosclerosis and microvascular disease. Reactions of glucose, or aldehydes derived from glucose (e.g. methylglyoxal, glyoxal, or glycolaldehyde), with proteins result in glycation that ultimately yield advanced glycation end products (AGE). AGE are present at elevated levels in plasma and atherosclerotic lesions from people with diabetes, and previous in vitro studies have postulated that the presence of these materials is deleterious to cell function. This accumulation of AGE and glycated proteins within cells may arise from either increased formation and/or ineffective removal by cellular proteolytic systems, such as the proteasomes, the major multi-enzyme complex that removes proteins within cells. In this study it is shown that whilst high glucose concentrations fail to modify proteasome enzyme activities in J774A.1 macrophage-like cell extracts, reactive aldehydes enhanced proteasomal enzyme activities. In contrast BSA, pre-treated with high glucose for 8 weeks, inhibited both the chymotrypsin-like and caspase-like activities. BSA glycated using methylglyoxal or glycolaldehyde, also inhibited proteasomal activity though to differing extents. This suppression of proteasome activity by glycated proteins may result in further intracellular accumulation of glycated proteins with subsequent deleterious effects on cellular function.

Brachial-ankle pulse wave velocity and cardiovascular risk factors in the non-diabetic and newly diagnosed diabetic Chinese: Guangzhou Biobank Cohort Study-CVD

BACKGROUND

Increased arterial stiffness is an important cause of cardiovascular disease (CVD). We examined determinants of arterial stiffness in subjects across strata of glycaemic status.

METHODS

A total of 1249 subjects from a sub-study of the Guangzhou Biobank Cohort Study (GBCS-CVD) had brachial-ankle pulse wave velocity (baPWV) measured by automatic oscillometric method. Major cardiovascular risk factors including glycosylated haemoglobin A1c (HbA(1c)), high sensitivity C-reactive protein (hsCRP), fasting triglyceride, low- and high-density lipoprotein cholesterol and both fasting and post 2-h oral glucose-load glucose, systolic and diastolic blood pressure were assessed.

RESULTS

In all, 649, 479 and 121 subjects were classified into normoglycaemia, impaired glucose metabolism (IGM) and newly diagnosed diabetes groups, respectively. Both age and systolic blood pressure were significantly associated with increased baPWV in all three groups (all p < 0.001). In both normoglycaemic and IGM groups, hsCRP and HbA(1c) were positively associated with baPWV (p from 0.04 to < 0.001), whereas current smoking and triglyceride were associated with baPWV in the normoglycaemic and IGM group, respectively (p = 0.04 and 0.001). No gender difference in baPWV was observed in the normoglycaemic or IGM groups. However, in the newly diagnosed diabetes group, men had higher baPWV than women (p = 0.01).

CONCLUSIONS

In the normoglycaemic and IGM subjects, after adjusting for age, blood pressure and other confounders, increasing HbA(1c) was associated with increased baPWV, suggesting a pathophysiological role of chronic glycaemia that can contribute to vascular disease risk in persons without diabetes.

Effect of intensive glycemic control on cardiovascular outcomes and all-cause mortality in type 2 diabetes: Overview and metaanalysis of five trials

More intensive diabetes control prevents microangiopathy in patients with both type 1 diabetes and type 2 diabetes. The data related to prevention of macrovascular disease in patients with type 2 diabetes are controversial. The data confirming benefit of the HbA(1c) levels below 6.5% came almost exclusively from epidemiological studies. The following article reviews the data from five large clinical randomized trials which compared the more intensive glucose lowering strategy with the standard antidiabetic treatment i.e. UKPDS, PROactive, ACCORD, ADVANCE and VADT. Metaanalysis of five trials showed a highly significant reduction of the incidence of non fatal myocardial infarction [OR 0.84 (95% CI 0.75-0.93), p = 0.001] in patients with intensive glycemic control. No significant differences were observed by combined analysis for the non-fatal stroke, cardiovascular mortality and all-cause mortality between the compared groups. The reason for the discordance of the results of the epidemiological and interventional studies is not clear. The possible explanations could include short duration of the trials to show effect of glucose lowering, as well as attenuating of the beneficial effect of better glycemic control by increased hypoglycemia-related mortality in patients with preexisting cardiovascular disease.

Delta-glycated hemoglobin: a novel independent risk factor for cardiovascular events in patients without diabetes mellitus

BACKGROUND

A single measurement of glycated hemoglobin (HbA1c) is a weak predictor for cardiovascular events in patients without Type 2 diabetes mellitus. We hypothesized that dynamic changes in HbA1c (Delta-HbA1c) would better predict cardiovascular outcome than a single value.

METHODS

In 99 consecutive patients with stable coronary artery disease (CAD) and without diabetes mellitus who were seen twice in our outpatient clinic (4-6 months apart) in 1998, Delta-HbA1c (follow-up HbA1c--baseline HbA1c) was assessed. Between August and September 2007 (mean observation period 9.1 yr), patients and their physicians were contacted by telephone to evaluate the incidence of cardiovascular endpoints. The combined primary endpoint of our study was defined as the incidence of myocardial infarction, stroke or death from any cause. The endpoints were validated by chart review.

RESULTS

Multivariate analysis demonstrated that the change of HbA1c between first and second examination in 1998 was the most powerful parameter for prediction of the combined primary endpoint in the next 9 yr. The hazard ratio was 5.03 [95% confidence interval (CI) 1.4-17.9] for any increase in HbA1c and 1.99 (95%CI 1.3-3.0) for an HbA1c increase of 0.3%. In addition, Kaplan-Meier survival analysis showed a significant association between endpoint-free survival and dynamic changes in HbA1c.

CONCLUSIONS

Hence, changes in the glucometabolic milieu within 4-6 months calculated by the difference of two values of HbA1c affect the long-term prognosis of patients with CAD but without diabetes mellitus.

The glycemic index and cardiovascular disease risk

Postprandial hyperglycemia is increasingly recognized as an independent risk factor for cardiovascular disease. Glycemic "spikes" may adversely affect vascular structure and function via multiple mechanisms, including (acutely and/or chronically) oxidative stress, inflammation, low-density lipoprotein oxidation, protein glycation, and procoagulant activity. Postprandial glycemia can be reliably predicted by considering both the amount and type of carbohydrate. In particular, the glycemic index (GI), a measure of postprandial glycemic potency weight for weight of carbohydrate, has provided insights that knowledge of the sugar or starch content has not. In prospective observational studies, dietary GI and/or glycemic load independently predict cardiovascular disease, with relative risk ratios of 1.2 to 1.7 comparing highest and lowest quintiles. In randomized controlled trials in overweight subjects, diets based on low-GI carbohydrates have produced better cardiovascular-related outcomes than conventional low-fat diets. Taken together, the findings suggest that health professionals may be able to improve cardiovascular outcomes by recommending the judicious use of low- GI/glycemic load foods.

Blood glucose and cerebrovascular disease in nondiabetic patients

The objective of this study was to determine if elevations in blood glucose, in a range classified as impaired fasting glucose, are associated with a greater incidence of cerebrovascular disease in nondiabetic patients. Morning blood glucose determinations were evaluated with respect to subsequent stroke using records from 28 477 nondiabetic patients. Strokes and transient ischemic attacks (TIA) were identified from ICD-9 coding for a new event more than a year after baseline glucose determinations. Of the patients studied, 593 suffered stroke or TIA over a total risk analysis time of 100 982 years. Higher baseline morning glucose (100 to 126 mg/dL vs under 100 mg/dL) was associated with 31% more diagnoses (2.4% vs 1.8%, P < .001). Incidence rate was 5.3 per 1000 patient-years for those patients with glucose over 100 mg/dL and 3.9 per 1000 patient-years for those with glucose under 100 mg/dL (P <.001). Kaplan-Meier analysis showed that elevated baseline glucose was associated with a progressive, increased risk with time. A Cox proportional hazards model with adjustment for age, body mass index, sex, creatinine, lipids, smoking, and medications showed that elevated fasting glucose was associated with an increased hazard for a new event (hazard ratio 1.24, 95% CI 1.05-1.46, glucose over 100 mg/dL vs under 100 mg/dL). Thus, patients with higher baseline blood glucose levels in the absence of diabetes and after adjustment for covariants have a significantly greater risk for development of cerebrovascular disease.

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

BACKGROUND

Evidence suggests that variations in fasting glucose and insulin amongst those without frank type 2 diabetes mellitus are important determinants of cardiovascular disease. However, the relative importance of variations in fasting insulin, glucose, and glycated haemoglobin as risk factors for cardiovascular disease in women without diabetes is unclear. Our aim was to determine the independent associations of fasting insulin, glucose, and glycated haemoglobin with coronary heart disease and stroke in older women.

METHODS AND FINDINGS

We undertook a prospective cohort study of 3,246 British women aged 60-79 y, all of whom were free of baseline coronary heart disease, stroke, and diabetes, and all of whom had fasting glucose levels below 7 mmol/l. Fasting insulin and homeostasis model assessment for insulin sensitivity (HOMA-S) were linearly associated with a combined outcome of coronary heart disease or stroke (n = 219 events), but there was no association of fasting glucose or glycated haemoglobin with these outcomes. Results were similar for coronary heart disease and stroke as separate outcomes. The age, life-course socioeconomic position, smoking, and physical activity adjusted hazard ratio for a combined outcome of incident coronary heart disease or stroke per one standard deviation of fasting insulin was 1.14 (95% CI 1.02-1.33). Additional adjustment for other components of metabolic syndrome, low-density lipoprotein cholesterol, fasting glucose, and glycated haemoglobin had little effect on this result.

CONCLUSIONS

Our findings suggest that in women in the 60-79 y age range, insulin resistance, rather than insulin secretion or chronic hyperglycaemia, is a more important risk factor for coronary heart disease and stroke. Below currently used thresholds of fasting glucose for defining diabetes, neither fasting glucose nor glycated haemoglobin are associated with cardiovascular disease.

Haemoglobin A1c (HbA1C) in Non-diabetic and Diabetic Vascular Patients. Is HbA1C an Independent Risk Factor and Predictor of Adverse Outcome?

BACKGROUND

Plasma Haemoglobin A1c (HbA1c) reflects ambient mean glycaemia over a 2-3 months period. Reports indicate that patients, with and without diabetes, with an elevated HbA1c have an increased risk of adverse outcome following surgical intervention. Our aim was to determine whether elevated plasma HbA1c level was associated with increased postoperative morbidity and mortality in patients undergoing vascular surgical procedures.

METHODS

Plasma HbA1c was measured prospectively in 165 consecutive patients undergoing emergency and elective vascular surgical procedures over a 6-month period. Patients were categorized into four groups depending on whether their plasma HbA1c was < or =6%, 6.1-7%, 7.1-8% or >8% and clinical data was entered into a prospectively maintained database. Patients were also classified by diabetic status with suboptimal HbA1c in a patient without diabetes being >6 to < or =7% and suboptimal HbA1c in a patient with diabetes being >7%. Patients with plasma HbA1c >7% were reclassified as having undiagnosed diabetes mellitus. Composite primary endpoints were all cause 30-day morbidity and mortality and all cause 6-month mortality. Composite secondary endpoints were procedure specific complications, adverse cardiac events, stroke, infection and mean length of hospital stay.

RESULTS

Of the 165 patients studied, 43 (26.1%) had diabetes and the remaining 122 (73.9%) did not. The mean age was 72 years and 59% were male. Suboptimal HbA1c levels were found in 58% patients without diabetes and in 51% patients with diabetes. In patients without diabetes those with suboptimal HbA1c levels (6-7%) had a significantly higher incidence of overall 30-day morbidity compared to patients with HbA1c levels < or =6% (56.5 vs 15.7%, p<0.001). Similarly, for patients with diabetes those with suboptimal HbA1c levels (HbA1c >7%) had a significantly higher incidence of 30-day morbidity compared to those with HbA1c levels < or =7% (59.1% vs 19%, p=0.018). Multivariate analysis revealed that a plasma HbA1c level of >6 to < or =7% was a significant independent predictor of overall 30-day morbidity in patients without diabetes undergoing vascular surgical procedures. No difference in mortality, composite secondary endpoints, procedure specific complications, stroke or mean length of hospital stay was observed between any of the groups in the study.

CONCLUSION

Suboptimal HbA1c levels may hold prognostic significance in patients without diabetes undergoing vascular surgery.

Combined effects of hemoglobin A1c and C-reactive protein on the progression of subclinical carotid atherosclerosis: the INVADE study

BACKGROUND AND PURPOSE

Glycohemoglobin (hemoglobin A1c [HbA1c]) and high-sensitivity C-reactive protein (hsCRP) are risk indicators for atherosclerosis. Limited information exists regarding the combined effects of inflammation and hyperglycemia. We investigated the joint effects of both parameters on early carotid atherosclerosis progression and major vascular events in diabetic and nondiabetic subjects.

METHODS

We analyzed the data of INVADE (Intervention Project on Cerebrovascular Diseases and Dementia in the Community of Ebersberg, Bavaria), a prospective, population-based study conducted in 3534 subjects (mean age, 69 years). In addition to common risk factors, measurements of carotid intima-media thickness (IMT), hsCRP, and HbA1c were performed at baseline and after 2 years of follow-up.

RESULTS

For the entire population, IMT progression was significantly related to HbA1c (P=0.003) but not to hsCRP (P=0.06) after risk factor adjustment. The interaction hsCRPxHbA1c was highly significant (P=0.001), and the most pronounced IMT progression was seen in subjects with both parameters in the fourth quartiles compared with subjects with both parameters in the first quartiles (0.028 [0.025, 0.031] versus 0.012 mm/year [0.007, 0.019]; P=0.0013). We observed a significant joint effect of HbA1c and hsCRP on IMT progression in the diabetic (n=882) as well as the nondiabetic subgroup (n=2652). Subjects with HbA1c and hsCRP in the upper 2 quartiles had an increased risk for new vascular events (adjusted hazard ratio in diabetics: 4.3 [1.8, 7.3]; P=0.001; nondiabetics: 2.9 [1.6, 4.7]; P=0.001).

CONCLUSIONS

The combination of hyperglycemia and inflammation is associated with an advanced early carotid atherosclerosis progression and an increased risk of new vascular events in diabetic as well as nondiabetic subjects.

Glycemic index, postprandial glycemia and cardiovascular disease

PURPOSE OF REVIEW

Several lines of evidence indicate that exaggerated postprandial glycemia puts individuals without diabetes at greater risk of developing cardiovascular disease. In large, prospective observational studies, including meta-analyses, higher 120 min post-load blood glucose and glycated hemoglobin (a measure of average blood glucose level over time) independently predict cardiovascular mortality and morbidity in individuals without diabetes. These findings imply that the glycemic nature of dietary carbohydrates may also be relevant. We aim to provide a clearer perspective on how the glycemic impact of carbohydrates may modulate development of cardiovascular disease.

RECENT FINDINGS

In ecological studies, average dietary glycemic index (a measure of the postprandial glycemic potential of carbohydrates) and glycemic load (average glycemic index x amount of carbohydrate) predicts coronary infarct and cardiovascular disease risk factors, including HDL cholesterol, triglycerides and C-reactive protein. In short-term intervention studies of overweight and hyperlipidemic patients, low glycemic index diets lead to improvements in cardiovascular disease risk factors, including reduced LDL cholesterol and improved insulin sensitivity, as well as greater body fat loss on energy-restricted diets. Molecular studies indicate that physiological hyperglycemia induces overproduction of superoxide by the mitochondrial electron-transport chain, resulting in inflammatory responses and endothelial dysfunction.

SUMMARY

Taken together, the findings suggest that conventional high-carbohydrate diets with their high glycemic index may be suboptimal, particularly in insulin-resistant individuals. Because around one in four adults has impairments in postprandial glucose regulation, the glycemic potential of carbohydrates warrants further investigation in cardiovascular disease prevention.