Skin Autofluorescence is Associated with Early-stage Atherosclerosis in Patients with Type 1 Diabetes

Skin Autofluorescence as a Potential Adjunctive Marker for Cardiovascular Risk Assessment in Type 2 Diabetes: A Systematic Review

Diabetes mellitus (DM), due to its long-term hyperglycemia, leads to the accumulation of advanced glycation end-products (AGEs), especially in the vessel walls. Skin autofluorescence (SAF) is a non-invasive tool that measures AGEs. DM patients have a rich dietary source in AGEs, associated with high oxidative stress and long-term inflammation. AGEs represent a cardiovascular (CV) risk factor, and they are linked with CV events. Our objective was to assess whether SAF predicts future CV events (CVE) by examining its association with other CV risk factors in patients with type 2 DM (T2DM). Additionally, we assessed the strengths and limitations of SAF as a predictive tool for CVE. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology, we conducted a systematic review with CRD42024507397 protocol, focused on AGEs, T2DM, SAF, and CV risk. We identified seven studies from 2014 to 2024 that predominantly used the AGE Reader Diagnostic Optic tool. The collective number of patients involved is 8934, with an average age of 63. So, SAF is a valuable, non-invasive marker for evaluating CV risk in T2DM patients. It stands out as a CV risk factor associated independently with CVE. SAF levels are influenced by prolonged hyperglycemia, lifestyle, aging, and other chronic diseases such as depression, and it can be used as a predictive tool for CVE.

Screening for Subclinical Atherosclerosis and the Prediction of Cardiovascular Events in People with Type 1 Diabetes

People with type 1 diabetes (T1D) have a high cardiovascular disease (CVD) risk, which remains the leading cause of death in this population. Despite the improved control of several classic risk factors, particularly better glycaemic control, cardiovascular morbidity and mortality continue to be significantly higher than in the general population. In routine clinical practice, estimating cardiovascular risk (CVR) in people with T1D using scales or equations is often imprecise because much of the evidence comes from pooled samples of people with type 2 diabetes (T2D) and T1D or from extrapolations of studies performed on people with T2D. Given that T1D onsets at a young age, prolonged exposure to the disease and its consequences (e.g., hyperglycaemia, changes in lipid metabolism or inflammation) have a detrimental impact on cardiovascular health. Therefore, it is critical to have tools that allow for the early identification of those individuals with a higher CVR and thus be able to make the most appropriate management decisions in each case. In this sense, atherosclerosis is the prelude to most cardiovascular events. People with diabetes present pathophysiological alterations that facilitate atherosclerosis development and that may imply a greater vulnerability of atheromatous plaques. Screening for subclinical atherosclerosis using various techniques, mainly imaging, has proven valuable in predicting cardiovascular events. Its use enables the reclassification of CVR and, therefore, an individualised adjustment of therapeutic management. However, the available evidence in people with T1D is scarce. This narrative review provides and updated overview of the main non-invasive tests for detecting atherosclerosis plaques and their association with CVD in people with T1D.

Molecular Linkage between Immune System Disorders and Atherosclerosis

A strong relationship exists between immune dysfunction and cardiovascular disease. Immune dysregulation can promote the development of cardiovascular diseases as well as exacerbate their course. The disorders may occur due to the presence of primary immune defects (currently known as inborn errors of immunity) and the more common secondary immune deficiencies. Secondary immune deficiencies can be caused by certain chronic conditions (such as diabetes, chronic kidney disease, obesity, autoimmune diseases, or cancer), nutritional deficiencies (including both lack of nutrients and bioactive non-nutrient compounds), and medical treatments and addictive substances. This article unravels the molecular linkage between the aforementioned immune system disorders and atherosclerosis.

Is skin autofluorescence a novel non-invasive marker in diabetes? A systematic review and meta-analysis of case-control studies

Background

The advanced glycation end product (AGE) is produced from the nonenzymatic reaction between glucose and macromolecules by aging. Accumulation of AGE causes functional and structural changes in body proteins that lead to impairment of tissue protein functions. We aimed to validate AGE measurement by skin autofluorescence (SAF) in diabetes mellitus (DM) compared to the nondiabetes population.

Materials and Methods

We searched the PubMed, Cochrane, and Scopus databases from their inception till September 18, 2022, for casecontrol studies measuring AGE by SAF. Nonhuman studies, as well as review articles, study proposals, editorials, case reports, or congress posters, were excluded. We used a random effects model to assess the standard mean difference (MD) of age, body mass index (BMI), HbA1c, and SAF between diabetes and nondiabetes individuals.

Results

Higher SAF in DM patients indicated more accumulation of AGE compared with the nondiabetic population. Furthermore, HbA1c was considerably higher in DM patients. The MD of age, male gender, and BMI were significantly different between the DM individuals, compared with nondiabetic subjects, which can lead to altered SAF level and AGE production. There was a remarkable heterogeneity between diabetes and nondiabetes when measuring age, gender, and BMI, as well as HbA1c and SAF level.

Conclusion

This study could not confirm the validity of SAF as a surrogate marker in diabetes patients. Interestingly, metabolic load and high BMI can increase SAF, considerably. Altogether, SAF could be helpful in the future as a marker for metabolic syndrome or diabetes.

Correlation Between Skin Autofluorescence and Muscle Activities of Lower Limb in Aging Without Disease and Disability

Skin autofluorescence is a useful index to estimate the accumulation of advanced glycation end-products in human tissues. Elderly persons with higher skin autofluorescence have lower muscle mass, muscle strength and muscle power, however, little is known about the relationship between the skin autofluorescence level and each muscle activity. We measured the values of skin autofluorescence from five places on a lower limb, and the signals of surface electromyogram during isometric contractions from five muscles on that, simultaneously. The waveforms of surface electromyogram were analyzed by Daubechies-4 wavelet transformation. The value of skin autofluorescence was increased in the proximal part of the lower limb compared with the value of the distal part. The principal component of surface electromyogram activity in a time-frequency domain was lower in the proximal part compared with that of the distal part. There was a weak negative correlation between the value of skin autofluorescence on the gluteal region and the value of the mean wavelet coefficient of the surface electromyogram signals within the gluteus maximus muscle. The higher accumulation of advanced glycation end-products on the gluteal region might suggest the lower muscle activity in aging without disease and disability.

Accumulation of Advanced Glycation End-Products in the Body and Dietary Habits

The formation of advanced glycation end-products (AGE) in tissues is a physiological process; however, excessive production and storage are pathological and lead to inflammation. A sedentary lifestyle, hypercaloric and high-fructose diet and increased intake of processed food elements contribute to excessive production of compounds, which are created in the non-enzymatic multi-stage glycation process. The AGE’s sources can be endogenous and exogenous, mainly due to processing food at high temperatures and low moisture, including grilling, roasting, and frying. Accumulation of AGE increases oxidative stress and initiates various disorders, leading to the progression of atherosclerosis, cardiovascular disease, diabetes and their complications. Inborn defensive mechanisms, recovery systems, and exogenous antioxidants (including polyphenols) protect from excessive AGE accumulation. Additionally, numerous products have anti-glycation properties, occurring mainly in fruits, vegetables, herbs, and spices. It confirms the role of diet in the prevention of civilization diseases.

Skin autofluorescence corresponds to microvascular reactivity in diabetes mellitus

Advanced glycation accelerated by chronic hyperglycaemia contributes to the development of diabetic vascular complications throughout several mechanisms. One of these mechanisms is supposed to be impaired microvascular reactivity, that precedes significant vascular changes. The aim of this study was to find an association between advanced glycation, the soluble receptor for AGEs (sRAGE), and microvascular reactivity (MVR) in diabetes. Skin autofluorescence (SAF), which reflects advanced glycation, was assessed by AGE-Reader, MVR was measured by laser Doppler fluxmetry and evaluated together with sRAGE in 43 patients with diabetes (25 Type 1 and 18 Type 2) and 26 healthy controls of comparable age. SAF was significantly higher in patients with diabetes compared to controls (2.4 ± 0.5 vs. 2.0 ± 0.5 AU; p < 0.01). Patients with diabetes with SAF > 2.3 AU presented significantly worse MVR in both post-occlusive reactive hyperaemia (PORH) on the finger and forearm, and thermal hyperaemia (TH), compared to patients with SAF < 2.3 AU. SAF was age dependent in both diabetes (r = 0.41, p < 0.01) and controls (r = 0.45, p < 0.05). There was no association between SAF and diabetes control expressed by glycated haemoglobin. A significant relationship was observed between SAF and sRAGE in diabetes (r = 0.56, p < 0.001), but not in controls. A significant inverse association was found between SAF and MVR on the forearm in diabetes (PORH: r = -0.42, p < 0.01; TH: r = -0.46, p < 0.005). Both advanced glycation expressed by higher SAF or sRAGE and impaired MVR are involved in the pathogenesis of vascular complications in diabetes, and we confirm a strong interplay of these processes in this scenario.

Clinical Significance of Non-invasive Skin Autofluorescence Measurement in Patients with Diabetes: A Systematic Review and Meta-analysis

BACKGROUND

Advanced glycation end products (AGE), one of the main factors causing diabetic end-organ damage, accumulate in long half-life proteins, such as skin and cartilage collagen. AGE measurement may offer additional evidence to predict diabetic vascular complications. Skin autofluorescence (SAF) is suggested as a non-invasive, quick, and reliable method to measure tissue AGE level. The aim of this study was to review and evaluate evidence on the clinical validation of SAF measurement in diabetes mellitus (DM) patients.

METHODS

In this systematic review and meta-analysis, we searched "PubMed" (MEDLINE) and "Cochrane" databases from their inception to 10 August 2021 for observational studies concerning SAF measurement in diabetic patients. The following key terms were used in advanced searching: "Diabetes", "Diabetes Mellitus"," DM", "Glycation ", "Advanced Glycation End product", "AGE", "skin autofluorescence", "SAF". Published studies that included DM patients and estimated their AGE using SAF were considered eligible for meta-analysis. Articles that were editorials, study proposals, congress posters, or case reports and were not on human subjects were excluded. We used a random-effect models for meta-analyzing the clinical validation of SAF in DM with particular emphasis on chronic diabetes complications.

FINDINGS

We identified 881 records and twenty-nine records fulfilled our eligibility criteria and were included in the systematic review and meta-analysis. A statistically significant correlation was found between SAF and diabetes last HbA1c 0.21(0.13,0.28) in studies with substantial heterogeneity (I2=77.99%, p<0.05). Nevertheless, a significant positive association between SAF level and diabetic retinopathy (DR) [(OR= 1.05, 95% CI=1.03,1.08), (I2=63.78%, p<0.05)], diabetic peripheral neuropathy (DPN) [(OR= 1.11, 95%CI= 1.06,1.16), (I2=79.17%, p<0.05)], diabetic nephropathy (DNP) [(OR= 1.08, 95%CI: 1.05,1.11), (I 2 =65.36%, p<0.05)] and diabetic macrovascular events (D-MVE) [(OR=1.08, 95%CI=1.05,1.11) (I2=67.32, p<0.05)] were found.

INTERPRETATION

Our study confirmed the significance of SAF measurement as a non-invasive surrogate marker of DM micro and macrovascular complications. Skin AGE estimation may be a useful factor for the prediction and early detection of irreversible DM complications. More studies with larger populations and longer follow-up periods are required.

Predictors of Change in Skin Intrinsic Fluorescence in Type 1 Diabetes: The Epidemiology of Diabetes Complications Study

BACKGROUND

Skin intrinsic fluorescent (SIF) scores are indirect measures of advanced glycation end-products (AGEs). SIF scores are cross-sectionally associated with type 1 diabetes (T1D) complications such as increased albumin excretion rate (AER), coronary artery calcification (CAC) and neuropathy. We assessed predictors of SIF score change in those with T1D.

METHODS

Data from the 30-year longitudinal Epidemiology of Diabetes Complications (EDC) study of childhood-onset T1D were used to assess AGEs measured with a SIF score produced by the SCOUT DS® device. SIF scores were assessed twice in 83 participants: between 2007-08 and again between 2010-14. Regression analyses were used to assess independent predictors of SIF score change.

RESULTS

At baseline, mean age was 47.9 ± 6.9 years, diabetes duration was 36.7 ± 6.4 years, and median glycosylated hemoglobin (HbA1c) was 7.1 (interquartile range: 6.5, 8.5). During a mean follow-up of 5.2 ± 0.9 years, mean change in SIF score was 2.9 ± 2.8 arbitrary units. In multivariable linear regression models, log HbA1c (P < 0.001), log estimated glomerular filtration rate (eGFR) (P < 0.001), overt nephropathy (defined as AER ≥ 200 µg/min, P = 0.06), and multiple daily insulin shots/pump use (MDI) exposure years (P = 0.02) were independent predictors of SIF score change.

CONCLUSIONS

Increases in SIF score over 5 years were related to increased glycemic levels and decreased kidney function (eGFR). MDI and glomerular damage were related to a decreased SIF score. This is one of the first studies with repeated SIF assessments in T1D and provides unique, albeit preliminary, insight about these associations.

Skin autofluorescence in people with type 1 diabetes and people without diabetes: An eight-decade cross-sectional study with evidence of accelerated aging and associations with complications

AIM

To measure skin autofluorescence in youth (<18 y.o.) and adults (≥18 y.o.) and to assess its relationship with type 1 diabetes, chronic complications and smoking.

METHODS

In a cross-sectional study (n = 383) skin autofluorescence was measured in 269 people with type 1 diabetes (67 with vascular complications) and 114 people without diabetes, covering eight decades of age. Associations of skin autofluorescence with demographics and traditional risk factors were assessed.

RESULTS

Skin autofluorescence increased with age in people with diabetes: for those with complications it increased by a mean ± se of 0.029 ± 0.003 arbitrary units per year (r = 0.76) and, for those without complications, it increased by 0.028 ± 0.002 arbitrary units (r = 0.77). These increases were higher than for people without diabetes, whose skin autofluorescence increased by 0.022 ± 0.002 arbitrary units (r = 0.78) per year (p = 0.004). Mean ±se age-adjusted skin autofluorescence was higher in people with diabetes complications vs people without diabetes complications (1.85 ± 0.04 vs 1.66 ± 0.02 arbitrary units) and people without diabetes (1.48 ± 0.03 arbitrary units; all P < 0.0001). Age-adjusted skin autofluorescence was higher in current smokers and recent ex-smokers vs non-smokers and longer-term ex-smokers (1.86 ± 0.06 vs 1.63 ± 0.02 arbitrary units; P = 0.0005). Skin autofluorescence area under the receiver-operating characteristic curve was 0.89 (95% CI 0.85-0.94) for retinopathy and 0.56 (95% CI 0.47-0.65) for nephropathy.

CONCLUSIONS

Skin autofluorescence increases with age, but faster in people with diabetes, particularly in those with complications and in smokers, consistent with accelerated aging. Skin autofluorescence may facilitate complication screening and prediction. Longitudinal studies are merited.

For diabetic type 1 patients, the skin autofluorescence predicts ulcers and amputations

We searched whether the accumulation of Advanced Glycation End-products (AGEs), reflected by the skin autofluorescence (SAF), could predict diabetic foot ulcers (DFUs) during the long-term follow-up of people with type 1 diabetes. During year 2009, we measured the SAF with an AGE-Reader in 206 subjects with type 1 diabetes. DFU and amputations were registered during the 10 following years. The relation between the SAF and later DFU was analyzed by Cox model regression, adjusted for vascular risk factors. The 206 participants were mainly men (55.8%), 51 ± 15 years old, with a 22 ± 13 years diabetes duration. Twelve subjects presented a DFU. Their SAF were higher: 2.61 ± 0.89 AU vs 2.11 ± 0.53 for the others (p = 0.003), related to the risk of DFU (OR:3.69; 95% CI: 1.06-12.79) after adjustment for age, gender, diabetes duration, initial HbA1c, arterial hypertension, history of smoking, blood lipids and use of a statin. Five subjects were amputated, also related to the initial SAF: OR: 11.28 (95% CI: 1.76-79.97) after adjustment for age, gender, duration of diabetes, and HbA1c. The SAF has already been related to diabetic neuropathy and peripheral arterial disease. It predicts DFU in type 1 diabetes, which suggests that AGEs play a role in this highly specific and feared complication.

Skin intrinsic fluorescence scores are a predictor of all-cause mortality risk in type 1 diabetes: The Epidemiology of Diabetes Complications study

AIMS

We assessed the association of skin intrinsic fluorescence (SIF) scores, as a measure of advanced glycation end-products (AGE), with all-cause mortality in type 1 diabetes (T1D).

METHODS

This is an observational retrospective study of a convenience sample from the Epidemiology of Diabetes Complications (EDC) study. AGEs were measured with a SIF score between 2007 and 2014; vital status was assessed in 2020.

RESULTS

Among 245 participants, mean age was 48.6 ± 7.4 years, median diabetes duration was 39.5 years (IQR: 34.2, 44.9), and 53.5% were female. Compared to survivors, the deceased (n = 20) were older, with higher SIF scores, longer diabetes duration, lower body mass index (BMI), and an adverse risk factor profile (all p≤0.05). Univariate Cox regression showed a marginal association between SIF score and mortality (HR: 1.1, 95% CI 0.9-1.2, p = 0.06), which persisted after adjustment for multiple daily insulin shots/pump (MDI) use (HR: 1.1, 95% CI 1.0-1.2, p = 0.04). This association was attenuated after adjustment for T1D duration, A_1c months, or estimated glomerular filtration rate (eGFR).

CONCLUSIONS

In individuals with long duration T1D, SIF scores adjusted for MDI predicted all-cause mortality, although this association was attenuated after adjustments. Given the nature of sampling and small number of events, our findings require replication.

Are Advanced Glycation End Products in Skin Associated with Vascular Dysfunction Markers? A Meta-Analysis

Evidence exists regarding the association between advanced glycation end products and different cardiovascular disease subclinical processes, such as arterial stiffness and atherosclerosis. With this systematic review and meta-analysis, we aimed to provide a synthesis of the evidence regarding the association of arterial stiffness measured by pulse wave velocity and atherosclerosis measured by carotid intima media thickness with skin autofluorescence. A systematic search was performed using: MEDLINE (PubMed), SCOPUS, and Web of Science, until 30 March 2020. Cross-sectional studies or baseline data from prospective longitudinal studies were considered. The DerSimonian and Laird method was used to calculate the pooled estimates of correlation coefficients and the corresponding 95% confidence intervals (CI) for the association of pulse wave velocity and carotid intima media thickness with skin autofluorescence. Twenty-five studies were included in the systematic review and meta-analysis, including 6306 subjects. The pooled correlation coefficient was 0.25 (95% CI: 0.18, 0.31) for pulse wave velocity and skin autofluorescence, and 0.31 (95% CI: 0.25, 0.38) for carotid intima media thickness and skin autofluorescence. This systematic review and meta-analysis provide a synthesis of the evidence showing a positive weak association of pulse wave velocity and carotid intima media thickness with skin autofluorescence.

One-hour plasma glucose combined with skin autofluorescence identifies subjects with pre-diabetes: the DIAPASON study

INTRODUCTION

The major challenge for diabetes prevention is early identification of individuals at risk to allow for implementation of measures to delay the onset of future disease. Measures such as fasting plasma glucose (FPG), 2-hour plasma glucose (2hPG), and glycosylated hemoglobin (HbA1c) are equally appropriate for identifying pre-diabetes and diabetes, but do not all identify the disease in the same individual. We tested the utility of a diagnostic method combining FPG, 2hPG and HbA1c for early evaluation and easy identification of pre-diabetes.

RESEARCH DESIGN AND METHODS

531 subjects underwent skin autofluorescence (SAF) and glycemia analyses. We created two classification groups based on the American Diabetes Association diagnosis guidelines: (1) based on 2hPG and (2) based on a new combination of three glycemia parameters (the three-criteria strategy (3-c)). Logistic regression modeling was used to estimate the associations.

RESULTS

SAF showed high associations for both 3-c definition and 2hPG definition alone. These associations appeared stronger in 3-c than those in 2hPG. The non-invasive SAF measurement outperformed 2hPG in the detection of dysglycemia or pre-diabetes. Stepwise selections identified 1-hour postload glucose (1hPG) as variable identifying pre-diabetes using the 2hPG criterion, and the model based on 1hPG plus SAF appeared to be the best association using the 3-c strategy.

CONCLUSIONS

1hPG coupled with SAF showed a strong association in the evaluation of pre-diabetes using the 3-c method.

The role of advanced glycation end products in vascular aging: which parameter is the most suitable as a biomarker?

Advanced glycation end products (AGEs) are involved in several pathophysiologic processes in vascular diseases, including progressive loss of elasticity of the vessel wall (arterial stiffness). Circulating soluble receptors for AGEs (sRAGE) act as a decoy and counterbalanced the harmful properties of AGEs as the natural protective factor. We compared the role of circulating or skin-deposed AGEs and sRAGE regarding the natural course of arterial stiffening. In a prospective cohort study, we longitudinally followed 536 general population-based subjects (subsample of Czech post-MONICA study). Aortic pulse-wave velocity (PWV) was measured twice (at baseline and after ~8 years of follow-up) using a SphygmoCor device (AtCor Medical Ltd), and the intraindividual change in PWV per year (∆PWV/year) was calculated. Concentrations of sRAGE and carboxymethyl lysine (circulating AGEs) were assessed at the follow-up visit by ELISA, while skin AGEs were measured using the autofluorescence-based device AGE Reader. Using multiple regressions, we found significant association between ∆PWV/year as a dependent variable, and both, sRAGE and skin AGEs as independent ones (each on its own model). However, the closest associations to ∆PWV/year were found for the ratio of these two factors (skin AGEs/sRAGE) [β coeff = 0.0747 (SE 0.0189), p < 0.0001]. In a categorized manner, subjects with skin AGEs/sRAGE ratio ≥ 3.3 showed about twofold higher risk having ΔPWV/year ≥ 0.2 m/s [adjusted odds ratio was 2.09 (95% CI: 1.35-3.22), p = 0.001]. In contrast, neither circulating AGEs nor circulating AGEs/sRAGE showed any significant relation to ΔPWV/year. In conclusion, skin AGEs/sRAGE ratio seems to be a more sensitive biomarker of vascular aging than these single factors themselves or circulation status of AGEs.

The Diabetes Mellitus-Atherosclerosis Connection: The Role of Lipid and Glucose Metabolism and Chronic Inflammation

Diabetes mellitus comprises a group of carbohydrate metabolism disorders that share a common main feature of chronic hyperglycemia that results from defects of insulin secretion, insulin action, or both. Insulin is an important anabolic hormone, and its deficiency leads to various metabolic abnormalities in proteins, lipids, and carbohydrates. Atherosclerosis develops as a result of a multistep process ultimately leading to cardiovascular disease associated with high morbidity and mortality. Alteration of lipid metabolism is a risk factor and characteristic feature of atherosclerosis. Possible links between the two chronic disorders depending on altered metabolic pathways have been investigated in numerous studies. It was shown that both types of diabetes mellitus can actually induce atherosclerosis development or further accelerate its progression. Elevated glucose level, dyslipidemia, and other metabolic alterations that accompany the disease development are tightly involved in the pathogenesis of atherosclerosis at almost every step of the atherogenic process. Chronic inflammation is currently considered as one of the key factors in atherosclerosis development and is present starting from the earliest stages of the pathology initiation. It may also be regarded as one of the possible links between atherosclerosis and diabetes mellitus. However, the data available so far do not allow for developing effective anti-inflammatory therapeutic strategies that would stop atherosclerotic lesion progression or induce lesion reduction. In this review, we summarize the main aspects of diabetes mellitus that possibly affect the atherogenic process and its relationship with chronic inflammation. We also discuss the established pathophysiological features that link atherosclerosis and diabetes mellitus, such as oxidative stress, altered protein kinase signaling, and the role of certain miRNA and epigenetic modifications.

Metabolic Syndrome Including Glycated Hemoglobin A1c in Adults: Is It Time to Change?

(1) Background: To assess the suitability of replacing conventional markers used for insulin resistance and dysglycemia by HbA1c in both the quantitative and qualitative metabolic syndrome (MetS) definition criteria; (2) Methods: Confirmatory factorial analysis was used to compare three quantitative definitions of MetS that consisted of many single-factor models, one of which included HbA1c as the dysglycemia indicator. After that, the model with the better goodness-of-fit was selected. Furthermore, a new MetS qualitative definition was proposed by replacing fasting plasma glucose with HbA1c > 5.7% in the International Diabetes Federation (IDF) definition. The clinical performance of these two MetS criteria (IDF and IDF-modified including HbA1c as the dysglycemia indicator) to predict vascular damage (pulse wave velocity [PWv], intima media thickness [IMT] and albumin-to-creatinine ratio [ACR]) was estimated; (3) Results: The single-factor model including HbA1c showed the better goodness-of-fit (χ² = 2.45, df = 2, p = 0.293, CFI = 0.999, SRMR = 0.010). Additionally, the IDF-modified criteria gained in clinical performance to predict vascular damage (diagnostic Odds Ratio: 6.94, 1.34 and 1.90) for pulse wave velocity (PWv), intima media thickness (IMT) and albumin-to-creatinine ratio (ACR), respectively; and (4) Conclusions: These data suggest that HbA1c could be considered as a useful component to be included in the MetS definition.

Skin Autofluorescence Measurement in Subclinical Atheromatous Disease: Results from the ILERVAS Project

Aim: Advanced glycation end-products (AGEs) have been involved in the atherogenic process in the high-risk population. The goal of this study was to demonstrate that AGEs are related to subclinical atheromatous disease in subjects with low to moderate vascular risk.

Methods: A cross-sectional study in which 2,568 non-diabetic subjects of both sexes without cardiovascular disease were included. Subcutaneous content of AGEs was assessed by skin autofluorescence (SAF) and subclinical atheromatous disease was measured by assessing the atheromatous plaque burden in carotid and femoral regions using ultrasonography. In addition, serum pentosidine, carboxymethyl-lysine (CML) and AGE receptors (RAGE) were assessed in a nested case-control study with 41 subjects without plaque and 41 individuals subjects with generalized disease.

Results: Patients with atheromatous plaque had a higher SAF than those with no plaque (1.9 [1.7 to 2.3] vs. 1.8 [1.6 to 2.1] arbitrary units (AU), p % 0.001). The SAF correlated with the total number of affected regions (r = 0.171, p < 0.001), increasing progressively from 1.8 [1.6 to 2.1] AU in those without atheromatous disease to 2.3 [1.9 to 2.7] AU in patients with ≥ 8 plaques (p < 0.001). A correlation was also observed between SAF and the total plaque area (r = 0.113, p < 0.001). The area under the Receiver Operating Characteristic curve was 0.65 (0.61 to 0.68) for identifying male subjects with atheromatous disease. The multivariable logistic regression model showed a significant and independent association between SAF and the presence of atheromatous disease. However, no significant differences in serum pentosidine, CML, and RAGE were observed.

Conclusions: Increased subcutaneous content of AGEs is associated with augmented atheromatous plaque burden. Our results suggest that SAF may provide clinically relevant information to the current strategies for the evaluation of cardiovascular risk, especially among the male population.

Relationships Between Skin Autofluorescence and Cardio-Ankle Vascular Index in Japanese Male Patients With Metabolic Syndrome

Background

An autofluorescence (AF) reader can be used to noninvasively measure tissues that accumulated advanced glycation end-products to diagnose skin AF. This study aimed to clarify the clinical significance of skin AF as a risk factor for cardiovascular disease in Japanese male patients with metabolic syndrome using the cardio-ankle vascular index (CAVI) as a marker of arterial function.

Methods

This cross-sectional study enrolled 261 Japanese male patients with metabolic syndrome without history of cardiovascular disease (mean age, 58 ± 7 years (mean ± standard deviation)). Associations between skin AF and various clinical parameters including CAVI were examined.

Results

Skin AF was significantly positively correlated with CAVI (r = 0.40, P < 0.001). Furthermore, multiple regression analyses revealed that skin AF (β = 0.18, P = 0.002) was selected as an independent subordinate factor for CAVI. Meanwhile, homeostatic model assessment of insulin resistance (HOMA-IR) as a marker of insulin resistance, smoking habits and high-sensitivity C-reactive protein as an inflammation marker were independent variables for either CAVI or skin AF as a subordinate factor. According to the receiver-operating characteristic curve analysis and results of previous reports that determined CAVI of ≥ 9.0 as a diagnostic criterion for vascular failure, skin AF of > 2.7 arbitrary unit is the optimal cut-off point for discriminating high CAVI (area under the curve = 0.718, P < 0.001).

Conclusion

Findings in this study indicate that skin AF may be an important risk factor of cardiovascular disease in Japanese male patients with metabolic syndrome. In addition, the risk value of skin AF was considered as higher than 2.7 arbitrary unit. Further investigations in a large number of prospective studies, including intervention therapies, are required to validate the results in this study.

Skin autofluorescence is associated with vascular complications in patients with type 2 diabetes

AIMS

Tissue accumulatedadvanced glycation end products (AGEs) can be evaluated non-invasively by an autofluorescence reader as skin autofluorescence (skin AF)·The present study investigated whether skin AF is associated with diabetic micro- and macroangiopathies in Japanese patients with type 2 diabetes mellitus (T2DM).

METHODS

Skin AF was measured in 193 enrolled Japanese patients with T2DM and 24 enrolled healthy non-diabetic subjects by using the AGE reader®. Diabetic micro- and macroangiopathies were evaluated in the T2DM patients.

RESULTS

Skin AF was significantly increased in patients with T2DM than in age- and sex-matched non-diabetic controls (2.35 ± 0.51 [mean ± SD] and 1.91 ± 0.29, respectively, p = 0.001). In subjects with T2DM, skin AF was associated with age, pack-years of smoking, and eGFR (estimated glomerular filtration rate) independently. Skin AF was significantly increased in patients with diabetic retinopathy, neuropathy, nephropathy, and macroangiopathy than in those without them, and significantly associated with the number of diabetic complications. Moreover, skin AF was an independent predictor for diabetic retinopathy, neuropathy, and nephropathy but not macroangiopathy, after adjusting for major traditional risk factors.

CONCLUSIONS

Skin AF is an independent predictor for diabetic retinopathy, neuropathy and nephropathy in Japanese patients with T2DM.

Association between Subclinical Atherosclerosis Markers and the Level of Accumulated Advanced Glycation End-Products in the Skin of Patients with Diabetes

Aim: The level of accumulated advanced glycation end-products (AGEs) in the skin has been shown to predict the risk of complications in patients with diabetes mellitus (DM). Recently, the level of accumulated fluorescent AGEs in the skin has become measurable as skin autofluorescence (skin AF) using a non-invasive apparatus, autofluorescence reader. The purpose of this study was to evaluate the association between skin AF and the subclinical atherosclerosis markers, especially endothelial dysfunction, in patients with DM.

Methods: We enrolled 140 Japanese subjects with DM who attended Osaka University Hospital, and measured the skin level of AGEs by skin AF and three subclinical atherosclerosis markers: endothelial function by flow-mediated vasodilation, FMD; carotid intima-media thickness, IMT; and brachial-ankle pulse wave velocity, baPWV.

Results: FMD was significantly associated with skin AF (r = −0.259, p = 0.002). Furthermore, a stepwise multivariate regression analysis revealed that skin AF was an independent determinant of FMD (β = −0.180, p = 0.038). Although there were significant associations between skin AF and maximum carotid intima-media thickness (max-IMT)(r = 0.298, p < 0.001) as well as baPWV (r = 0.284, p = 0.001) in univariate analysis, skin AF was not an independent determinant of either carotid max-IMT or baPWV after adjustment for conventional cardiovascular risk factors. Receiver-operating characteristic curve analysis revealed that skin AF can identify the subjects whose FMD, max-IMT, and baPWV were completely within the normal range (C-statistics, 0.73; 95% confidence interval, 0.61–0.84; p < 0.001).

Conclusions: Skin AF was independently associated with FMD as an indicator of endothelial dysfunction, and can be utilized as a screening marker of atherosclerosis in Japanese patients with DM.

Diabetic retinopathy is associated with the presence and burden of subclinical carotid atherosclerosis in type 1 diabetes

Background

Cardiovascular (CV) disease due to atherosclerosis is a major cause of morbidity and mortality in adult patients with diabetes, either type 1 or type 2 diabetes. The aim of the study was to assess the association of the frequency and the burden of subclinical carotid atherosclerotic disease in patients with type 1 diabetes according to the presence and severity of diabetic retinopathy (DR).

Methods

A cross-sectional study was conducted in 340 patients with type 1 diabetes (41.5% with DR), and in 304 non-diabetic individuals. All participants were free from previous CV disease and chronic kidney disease (CKD). B-mode carotid ultrasound imaging was performed in all the study subjects. Patients with type 1 diabetes underwent a full eye examination, and DR patients were divided into two groups: mild disease and advanced disease.

Results

In the group of patients with type 1 diabetes, the percentage of patients with carotid plaques was higher in those with DR compared with those without DR (44.7% vs. 24.1%, p < 0.001). Patients with DR also presented a higher incidence of ≥ 2 carotid plaques (25.5% vs. 11.1%, p < 0.001). Apart from other traditional cardiovascular risk factors, the presence of advanced stages of DR was independently associated with the presence (p = 0.044) and the burden (≥ 2 carotid plaques; p = 0.009) of subclinical carotid atherosclerosis.

Conclusions

In patients with type 1 diabetes without previous CV disease or established CKD, the presence of advanced stages of DR is associated with a higher atherosclerotic burden in the carotid arteries. The presence of DR identifies patients at risk for carotid atherosclerotic disease.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0706-z) contains supplementary material, which is available to authorized users.

Skin Autofluorescence is a Noninvasive Surrogate Marker for Diabetic Microvascular Complications and Carotid Intima-Media Thickness in Japanese Patients with Type 2 Diabetes: A Cross-sectional Study

INTRODUCTION

Advanced glycation end-products (AGEs) are known to play an important role in the pathogenesis of diabetic complications. Skin autofluorescence (AF), a marker of AGE accumulation in tissue, can be measured noninvasively using a skin AF reader. The present study aimed to evaluate the relationships of skin AF with diabetic microvascular complications and carotid intima-media thickness (IMT), a surrogate marker for atherosclerosis, in Japanese subjects with type 2 diabetes (T2D).

METHODS

One hundred sixty-two subjects with T2D and 42 nondiabetic control subjects attending the outpatient clinic were examined. Skin AF and carotid max-IMT were measured using an AGE Reader™ and ultrasonography, respectively. Nephropathy was classified into five stages based on the urinary albumin-to-creatinine ratio (UACR) as follows: (1) pre-nephropathy (stage 1) (UACR < 30 mg/g Cr); (2) incipient nephropathy (stage 2) (30 ≤ UACR < 300 mg/g Cr); (3) overt nephropathy (stage 3) (UACR ≥ 300 mg/g Cr); (4) kidney failure (stage 4) (estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73²); and (5) dialysis therapy (stage 5). Patients with kidney failure and those receiving dialysis therapy were excluded because the sample size was too small. Retinopathy was diagnosed as nondiabetic retinopathy (NDR), nonproliferative retinopathy (NPDR), or proliferative retinopathy (PDR). Diabetic peripheral neuropathy (DPN) was diagnosed if two or more of the following were present: neuropathic symptoms (decreased sensation, positive neuropathic sensory symptoms), symmetric decreased distal sensation, and unequivocally decreased or absent ankle reflexes.

RESULTS

Skin AF values were significantly higher in subjects with T2D (2.53 ± 0.45 AU) than in nondiabetic subjects (2.19 ± 0.34 AU, p < 0.001). Skin AF significantly increased with the severity of DPN (2.39 ± 0.37 with DPN vs 2.80 ± 0.48 without DPN, p < 0.001), retinopathy (NDR 2.42 ± 0.45, mild and moderate NPDR 2.64 ± 0.42, p = 0.042, severe NPDR and PDR 2.85 ± 0.35, p < 0.001), and nephropathy (pre-nephropathy 2.42 ± 0.44, incipient nephropathy 2.62 ± 0.45, p = 0.049, overt nephropathy 2.59 ± 0.46, p = 0.80). Skin AF was an independent determinant of the presence of DPN (OR 8.49, 95% CI 2.04-44.32, p = 0.006) and retinopathy (OR 3.73, 95% CI 1.20-12.90, p = 0.028) but not of diabetic nephropathy after correcting for confounding factors. In addition, skin AF (β = 0.170, p = 0.029) was an independent determinant of max-IMT, as was age (β = 0.436, p < 0.0001), after adjusting for other risk factors.

CONCLUSION

Skin AF as measured using an AGE Reader is a noninvasive surrogate marker for diabetic microvascular complications and early-stage atherosclerosis.

Mechanism of Development of Atherosclerosis and Cardiovascular Disease in Diabetes Mellitus

Diabetic macroangiopathy, atherosclerosis secondary to diabetes mellitus (DM), causes cerebro-cardiovascular diseases, which are major causes of death in patients with DM and significantly reduce their quality of life. The alterations in vascular homeostasis due to endothelial and vascular smooth muscle cell dysfunction are the main features of diabetic macroangiopathy. Although multiple metabolic abnormalities that characterize diabetes are involved in the progression of atherosclerosis in patients with DM, it may be said that prolonged exposure to hyperglycemia and insulin resistance clustering with other risk factors such as obesity, arterial hypertension, and dyslipidemia play crucial roles. Laboratory and clinical researches in the past decades have revealed that major biochemical pathways involved in the development of diabetic macroangiopathy are as follows: overproduction of reactive oxygen species, increased formation of advanced glycation end-products (AGEs) and activation of the AGEs-receptor for AGE axis, polyol and hexosamine flux, protein kinase C activation, and chronic vascular inflammation. Among them, oxidative stress is considered to be a key factor.

Measurement and Clinical Significance of Biomarkers of Oxidative Stress in Humans

Oxidative stress is the result of the imbalance between reactive oxygen species (ROS) formation and enzymatic and nonenzymatic antioxidants. Biomarkers of oxidative stress are relevant in the evaluation of the disease status and of the health-enhancing effects of antioxidants. We aim to discuss the major methodological bias of methods used for the evaluation of oxidative stress in humans. There is a lack of consensus concerning the validation, standardization, and reproducibility of methods for the measurement of the following: (1) ROS in leukocytes and platelets by flow cytometry, (2) markers based on ROS-induced modifications of lipids, DNA, and proteins, (3) enzymatic players of redox status, and (4) total antioxidant capacity of human body fluids. It has been suggested that the bias of each method could be overcome by using indexes of oxidative stress that include more than one marker. However, the choice of the markers considered in the global index should be dictated by the aim of the study and its design, as well as by the clinical relevance in the selected subjects. In conclusion, the clinical significance of biomarkers of oxidative stress in humans must come from a critical analysis of the markers that should give an overall index of redox status in particular conditions.