Reference values of skin autofluorescence as an estimation of tissue accumulation of advanced glycation end products in a general Slovak population

Assessment of Skin Autofluorescence and Its Association with Glycated Hemoglobin, Cardiovascular Risk Markers, and Concomitant Chronic Diseases in Children with Type 1 Diabetes

Skin autofluorescence (sAF) measurement is a non-invasive method used to assess tissue advanced glycation end product (AGE) accumulation. This study aims to characterize sAF's association with (1) glycated hemoglobin (HbA1c) values, (2) cardiovascular risk markers, and (3) common comorbidities (autoimmune thyroiditis, celiac disease) in children with type 1 diabetes (T1D).

MATERIALS AND METHODS

A total of 348 children with T1D aged 3-18 years and 85 age- and gender-matched control subjects were enrolled. sAF was quantified using an AGE Reader (Diagnoptics BV, The Netherlands). The analysis covered HbA1c, blood lipid, and C-reactive protein (CRP) levels, ambulatory blood pressure monitoring records, and body composition parameters. The associations between variables and sAF were assessed using the Mann-Whitney U test and Spearman correlation.

RESULTS

We observed significantly higher sAF values in the T1D group compared to the control (1.40 [1.27-1.53] vs. 1.20 [1.07-1.30, AU]; p = 0.004), consistent across all tested age groups. In the T1D group, sAF was positively correlated with current HbA1c, mean of historical HbA1c values, and T1D duration (r values, respectively: 0.27, 0.22, 0.14, all p < 0.01). Percentage of body fat was positively correlated with sAF (r = 0.120; p = 0.044). No significant correlations were found between sAF and lipid fractions, Z-score of BMI, parameters from 24 h ambulatory blood pressure monitoring, or the amount of albumin excreted in urine. sAF was positively correlated with CRP (r = 0.17, p < 0.05). sAF was significantly higher in patients with concomitant celiac disease (1.53 [1.43-1.63] vs. 1.40 [1.27-1.53, AU], p = 0.001).

CONCLUSION

Among young T1D patients with relatively brief diabetes duration, sAF effectively mirrors prior glycemic control, as presented by historical average HbA1c. However, associations with conventional CV risk markers are not evident. The higher sAF values in patients with celiac disease warrant further exploration.

The Bright Side of Skin Autofluorescence Determination in Children and Adolescents with Newly Diagnosed Type 1 Diabetes Mellitus: A Potential Predictor of Remission?

Skin autofluorescence (SAF) is a noninvasive method reflecting tissue accumulation of advanced glycation end products (AGEs). We investigated whether, in newly diagnosed children and adolescents with type 1 diabetes (T1D), this surrogate marker of long-term glycemia is associated with markers of the early manifestation phase, residual secretion capacity of the ß-cells, and the occurrence of remission. SAF was measured in 114 children and adolescents (age: 8.0 ± 4.5 years, 44% girls) at the time of T1D diagnosis, and related to HbA1c, C-peptide, diabetic ketoacidosis, and remission. 56 patients were followed up for 1 year. Seventy-four sex- and age-matched healthy individuals served as controls. SAF was higher in the T1D group compared with controls (1.0 ± 0.2 vs. 0.9 ± 0.2, p < 0.001). At the time of diagnosis, SAF correlated with HbA1c (r = 0.285, p = 0.002), was similar in patients with and without ketoacidosis, and was lower in the remitters compared with non-remitters (0.95 ± 0.18 vs. 1.04 ± 0.26, p = 0.027). Unlike HbA1c, SAF was an independent predictor of remission (∆R² = 0.051, p = 0.004). Former studies consider SAF in diabetic patients as a tool to identify individuals at an increased risk of chronic complications. Here we show that determination of SAF at the time of T1D diagnosis might potentially predict remission, at least in children.

A physically active lifestyle is related to a lower level of skin autofluorescence in a large population with chronic-disease (LifeLines cohort)

BACKGROUND

Physical activity (PA) has substantial health benefits and is important in combatting chronic diseases, which have been associated with elevated levels of advanced glycation endproducts (AGEs). AGEs play a role in the aging process, and an association between PA and AGEs has been reported. We aimed to investigate the relationship between PA and AGE accumulation in a general population and in a population with chronic diseases.

METHODS

This large cross-sectional population study used data from adult participants in the LifeLines project, with participant information drawn from the LifeLines database as well data from patients with diabetes mellitus or renal and/or cardiovascular diseases. Tissue AGE accumulation was assessed non-invasively by skin-autofluorescence (SAF) using an AGE reader (DiagnOptics Technologies BV, Groningen, the Netherlands). PA was assessed using the short questionnaire to assess health-enhancing physical activity (SQUASH). Multivariate linear regression analyses were adjusted for age, body mass index, sex, and smoking status.

RESULTS

Data from 63,452 participants (general population n = 59,177, chronic disease n = 4275) were analyzed. The general population was significantly younger (43.58 ± 11.77 years, mean ± SD) and had significantly lower SAF (1.90 ± 0.42 arbitrary units (AU)) compared to the population with chronic disease (age: 55.51 ± 12.07 years; SAF: 2.27 ± 0.51 AU). In the group with chronic disease, more hours of moderate to vigorous physical activities per week were associated with lower SAF (β = -0.002, 95% confidence interval (95%CI): -0.002 to -0.001). For the general population, there was no association between hours of moderate to vigorous activity and SAF (β = 3.2  × 10^-5, 95%CI: 0.000-0.001, p = 0.742). However, there was an association in the general population between total hours of PA per week and SAF (β = 4.2 × 10^-4, 95%CI: 0.000-0.001, p < 0.001), but this association was not found in the chronic disease population (β = -3.2 × 10^-4, 95%CI: -0.001 to 0.000, p = 0.347).

CONCLUSION

Our study demonstrates that an inverse relationship exists between PA and AGE accumulation in the population with chronic disease. More hours of moderate to vigorous activity is associated with a significantly decreased SAF. More PA is associated with a lower SAF, even after adjusting for the established predictors (age, body mass index, smoking status, and sex). Our findings could help to promote health and prolong longevity.

Skin Autofluorescence in Young Adult Offspring of Women with Type 1 Diabetes: A Cross-Sectional Case-Control Study

INTRODUCTION

Offspring born to women with type 1 diabetes pregnancies have an elevated risk for early-onset obesity and type 2 diabetes compared with offspring born to women without diabetes. Skin autofluorescence (SAF) is a marker of accumulated advanced glycation end products (AGEs) and it has been shown to predict type 2 diabetes, cardiovascular disease, and mortality in the general population. The aim of this study was to evaluate whether maternal type 1 diabetes influences the SAF value in young adult offspring.

METHODS

This cross-sectional case-control study included 78 offspring of women with type 1 diabetes (cases) and 85 control participants (controls). All study participants, aged 18-23 years, were invited to participate in a clinical assessment including laboratory tests and questionnaires. SAF was assessed using the AGE reader from the dominant forearm of each participant.

RESULTS

The mean SAF value did not differ between the cases (1.61 [standard deviation (SD) 0.37]) arbitrary units [AU]) and the controls (1.64 [SD 0.41] AU) (p = 0.69). After adjusting for glycated hemoglobin A_1c, body fat percentage, smoking, and season the mean SAF value did not differ between the cases and the controls (p = 0.49) but differed between men and women (p = 0.008), without any interaction observed (p = 0.78).

CONCLUSION

SAF values did not differ between the young adult offspring of women with type 1 diabetes and offspring born to mothers without diabetes. Surprisingly, young adult women showed higher SAF values than men in both case and control groups.

The AGE Reader: A non-invasive method to assess long-term tissue damage

AIMS

Advanced glycation endproducts (AGEs) are sugar-modified adducts which arise during non-enzymatic glycoxidative stress. These compounds may become systemically elevated in disease states, and accumulate in tissue, especially on long-lived proteins. AGEs have been implicated in various acute, and chronic diseases, stressing the need for reliable and comprehensive measuring techniques. Measurement of AGEs in tissue such as skin requires invasive skin biopsies. The AGE Reader has been developed to assess skin autofluorescence (SAF) non-invasively using the fluorescent properties of several AGEs.

RESULTS/CONCLUSION

Various studies have shown that SAF is a useful marker of disease processes associated with oxidative stress. It is prospectively associated with the development of cardiovascular events in patients with diabetes, renal or cardiovascular disease, and it predicts diabetes, cardiovascular disease, and mortality in the general population. However, when measuring SAF in individual subjects, several factors may limit the reliability of the measurement. These include endogenous factors present in the skin that absorb emission light such as melanin in dark-skinned subjects, but also factors that lead to temporal changes in SAF such as acute diseases and strenuous physical exercise associated with glycoxidative stress. Also, exogenous factors could potentially influence SAF levels inadvertently such as nutrition, and for example the application of skin care products. This review will address the AGE Reader functionality and the endogenous, and exogenous factors which potentially influence the SAF assessment in individual subjects.

Association of physical fitness with skin autofluorescence-derived advanced glycation end products in children

BACKGROUND

Advanced glycation end products (AGEs) accumulate with age and development of cardiovascular disease. Higher AGEs have been shown in children with diabetes but little is known about their association with lifestyle conditions in childhood. We hypothesized that BMI, blood pressure and cardiorespiratory fitness (CRF) are associated with subcutaneous AGEs formation in children.

METHODS

In this cross-sectional study, 1075 children (aged 7.2 ± 0.4 years) were screened for subcutaneous AGEs (skin autofluorescence; SAF), body mass index (BMI), blood pressure (BP), and CRF using standardized procedures. Group comparisons were performed in clinical BP and BMI categories and tertiles of CRF.

RESULTS

Children with higher physical fitness showed lower SAF (0.99(1.03;1.10)au) compared to children with low CRF (1.09(1.03;1.05)au, p < 0.001). An increase of one shuttle run stage was associated with a mean reduction in SAF of -0.033(CI: -0.042;-0.024)au, independent of BMI and BP (p < 0.001). BMI and BP were not independently associated with SAF-derived AGEs in this large cohort of primary school children.

CONCLUSIONS

Low physical fitness but not BMI and BP were associated with higher levels of AGEs. Primary prevention programs in young children may need to focus on improving physical fitness in game settings in order to reduce the growing prevalence of metabolic disorders during childhood.

Advanced Glycation End Products Are Associated With Physical Activity and Physical Functioning in the Older Population

Background

Decline in physical activity and functioning is commonly observed in the older population and might be associated with biomarkers such as advanced glycation end products (AGEs). AGEs contribute to age-related decline in the function of cells and tissues in normal aging and have been found to be associated with motor function decline. The aim of this study is to investigate the association between the levels of AGEs, as assessed by skin autofluorescence, and the amount of physical activity and loss of physical functioning in older participants.

Methods

Cross-sectional data of 5,624 participants aged 65 years and older from the LifeLines Cohort Study were used. Linear regression analyses were utilized to study the associations between skin autofluorescence/AGE levels (AGE Reader), the number of physically active days (SQUASH), and physical functioning (RAND-36). A logistic regression analysis was used to study the associations between AGE levels and the compliance with the Dutch physical activity guidelines (SQUASH).

Results

A statistical significant association between AGE levels and the number of physically active days (β = -0.21, 95% confidence interval: -0.35 to -0.07, p = .004), physical functioning (β = -1.60, 95% confidence interval: -2.64 to -0.54, p = .003), and compliance with the Dutch physical activity guidelines (odds ratio = 0.76, 95% confidence interval: 0.62 to 0.94, p = .010) was revealed.

Conclusions

This study indicates that high AGE levels may be a contributing factor as well as a biomarker for lower levels of physical activity and functioning in the older population.

Clinical Significance of Skin Autofluorescence in Elderly Patients With Long-Standing Persistent Atrial Fibrillation

Background

Recent clinical studies have demonstrated the importance of skin autofluorescence as a cardiovascular risk factor. However, data regarding the relationship between skin autofluorescence and atrial fibrillation are limited. The aim of this study was to clarify the clinical significance of skin autofluorescence in elderly patients with long-standing persistent atrial fibrillation.

Methods

This cross-sectional study enrolled 112 elderly patients with long-standing persistent atrial fibrillation who were treated medically (46 men and 66 women; mean age, 81 ± 9 years). The association between skin autofluorescence and various clinical parameters was examined.

Results

Significant relationships were observed between skin autofluorescence and CHADS₂ score (r = 0.53, P < 0.001), high-sensitivity cardiac troponin T level (r = 0.43, P < 0.001), reactive oxygen metabolite levels (r = 0.52, P < 0.001), and whole blood passage time (r = 0.45, P < 0.001). Furthermore, multiple regression analyses showed that these clinical parameters were independent variables when skin autofluorescence was used as a subordinate factor. Receiver-operating characteristic curve analysis indicated that the risk values of skin autofluorescence for high CHADS₂ scores (≥ 2) or elevated high-sensitivity cardiac troponin T levels (> 0.014ng/mL) were 2.6 arbitrary units (AU) and 2.7 AU, respectively.

Conclusions

The findings of this study indicated that skin autofluorescence may be a prognostic factor in elderly patients with long-standing persistent atrial fibrillation. The risk value of skin autofluorescence was considered as 2.6 AU or 2.7 AU.

Skin autofluorescence in children with and without obesity

Background Obesity is associated with oxidative stress, which is related to increased advanced glycation end product (AGE) formation. AGEs accumulated in skin collagen can be measured with skin autofluorescence (sAF). There are conflicting reports on the influence of obesity on sAF in adults and no data in children. Therefore, this study evaluated sAF in pediatric patients with and without obesity. Methods In this cross-sectional study, participants aged 4-18 years were included: patients with obesity (body mass index standard deviation score [BMI-SDS] >2.3) and lean controls (BMI-SDS >-1.1 to <1.1). sAF was measured using the AGE Reader®. Participants were stratified according to age (<10, ≥10 to <13, ≥13 to <15, ≥15 to <17 and ≥17 years) and skin type (I-VI). Results In total, 143 patients and 428 controls were included. In patients, there was no influence of age on sAF (p=0.09). In controls, sAF was higher in children aged <10 years compared to ≥10 to <13 and ≥13 to <15 years (p=0.02; p=0.04). Stratified by age, sAF was higher in patients compared to controls in all age categories, except <10 years of age (p<0.01), while this was not observed when stratified by skin type (p>0.05). Skin type and BMI were significant covariates for sAF. Conclusions BMI was a covariate for sAF; however, no difference in sAF was observed between children with and without obesity, stratified by skin type. Duration of obesity as well as accuracy of the AGE Reader® might explain this difference. Further research is warranted, in which patients should be matched for age and skin type.

Glycated proteins in nutrition: Friend or foe?

Advanced glycation end products (AGEs) are formed in in vivo, and accumulate in tissues and body fluids during ageing. Endogenous AGE-modified proteins show altered structure and function, and may interact with receptor for AGEs (RAGE) resulting in production of reactive oxygen species, inflammatory, atherogenic and diabetogenic responses. AGEs are also formed in thermally processed foods. Studies in rodents document that dietary AGEs are partially absorbed into circulation, and accumulate in different tissues. Knowledge on the health effects of high dietary intake of AGEs is incomplete and contradictory. In this overview we discuss the data from experimental and clinical studies, either those supporting the assumption that restriction of dietary AGEs associated with health benefits, or data suggesting that dietary intake of AGEs associates with positive health outcomes. We polemicize whether the effects of exaggerated intake or restriction of highly thermally processed foods might be straightforward interpreted as the effects of AGEs-rich vs. AGEs-restricted diets. We also underline the lack of studies, and thus a poor knowledge, on the effects of different single chemically defined AGEs administration, concurrent intake of different dietary AGEs, of load with dietary AGEs corresponding to the habitual diet in humans, and on those of dietary AGEs in vulnerable populations, such as infants and particularly elderly.

Skin autofluorescence: Correlation with measures of diabetic sensorimotor neuropathy

OBJECTIVE

Advanced glycation end products (AGE) contribute to the development of diabetes complications. Their accumulation in skin can be non-invasively assessed by measurement of skin autofluorescence (SAF). Our study investigated whether SAF correlates with measures of diabetic peripheral neuropathy (DPN).

METHODS

In a multi-center study (8 centers), 497 consecutive individuals with diabetes mellitus were investigated. Forearm SAF was measured using the AGE Reader (Groningen, The Netherlands). DPN was assessed using the Toronto Clinical Neuropathy Score (TCNS), the Neuropathy Symptoms Score (NSS) and the Neuropathy Disability Score (NDS). RESULTS (MEAN ± SD): According to the TCNS, SAF (arbitrary units - AU) was increased in individuals with DPN (TCNS > 5): 2.59 ± 0.56 AU compared with those without DPN (TCNS ≤ 5): 2.45 ± 0.53 AU, (p = 0.04) and significantly increased with the severity of DPN (p = 0.028). Higher SAF was detected in individuals with neuropathic deficits (NDS > 2): 2.58 ± 0.56 AU vs. those without deficits (NDS ≤ 2): 2.45 ± 0.53 AU, (p = 0.009) as well as in individuals with symptoms (NSS > 2): 2.54 ± 0.56 AU vs. those without symptoms (NSS ≤ 2): 2.40 ± 0.47 AU, (p = 0.022).

CONCLUSIONS

Accumulation of AGE in skin is increased in individuals with DPN and progresses with the severity of DPN. Therefore, SAF measurement, an easy-to-use, quick and non-invasive method, might help in identifying subjects at high risk for having DPN.

Skin autofluorescence predicts major adverse cardiovascular events in patients with type 1 diabetes: a 7-year follow-up study

Background

Advanced glycation end-products play a role in diabetic vascular complications. Their optical properties allow to estimate their accumulation in tissues by measuring the skin autofluorescence (SAF). We searched for an association between SAF and major adverse cardiovascular events (MACE) incidence in subjects with Type 1 Diabetes (T1D) during a 7 year follow-up.

Methods

During year 2009, 232 subjects with T1D were included. SAF measurement, clinical [age, sex, body mass index (BMI), comorbidities] and biological data (HbA1C, blood lipids, renal parameters) were recorded. MACE (myocardial infarction, stroke, lower extremity amputation or a revascularization procedure) were registered at visits in the center or by phone call to general practitioners until 2016.

Results

The participants were mainly men (59.5%), 51.5 ± 16.7 years old, with BMI 25.0 ± 4.1 kg/m², diabetes duration 21.5 ± 13.6 years, HbA1C 7.6 ± 1.1%. LDL cholesterol was 1.04 ± 0.29 g/L, estimated Glomerular Filtration Rates (CKD-EPI): 86.3 ± 26.6 ml/min/1.73 m². Among these subjects, 25.1% were smokers, 45.3% had arterial hypertension, 15.9% had elevated AER (≥ 30 mg/24 h), and 9.9% subjects had a history of previous MACE. From 2009 to 2016, 22 patients had at least one new MACE: 6 myocardial infarctions, 1 lower limb amputation, 15 revascularization procedures. Their SAF was 2.63 ± 0.73 arbitrary units (AU) vs 2.08 ± 0.54 for other patients (p = 0.002). Using Cox-model, after adjustment for age (as the scale time), sex, diabetes duration, BMI, hypertension, smoking status, albumin excretion rates, statin treatment and a previous history of MACE, higher baseline levels of SAF were significantly associated with an increased risk of MACE during follow-up (HR = 4.13 [1.30–13.07]; p = 0.02 for 1 AU of SAF) and Kaplan–Meier curve follow-up showed significantly more frequent MACE in group with SAF upper the median (p = 0.001).

Conclusion

A high SAF predicts MACE in patients with T1D.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0718-8) contains supplementary material, which is available to authorized users.

Ethnicity and skin autofluorescence-based risk-engines for cardiovascular disease and diabetes mellitus

Skin auto fluorescence (SAF) is used as a proxy for the accumulation of advanced glycation end products (AGEs) and has been proposed to stratify patients into cardiovascular disease (CVD) and diabetes mellitus (DM) risk groups. This study evaluates the effects of seven different ethnicities (Arab, Central-East African, Eastern Mediterranean, European, North African, South Asian and Southeast Asian) and gender on SAF as well as validating SAF assessment as a risk estimation tool for CVD and DM in an Arabian cohort. SAF data from self-reported healthy 2,780 individuals, collated from three independent studies, has been linear modelled using age and gender as a covariate. A cross-study harmonized effect size (Cohens’d) is provided for each ethnicity. Furthermore, new data has been collected from a clinically well-defined patient group of 235 individuals, to evaluate SAF as a clinical tool for DM and CVD-risk estimation in an Arab cohort. In an Arab population, SAF-based CVD and/or DM risk-estimation can be improved by referencing to ethnicity and gender-specific SAF values. Highest SAF values were observed for the North African population, followed by East Mediterranean, Arab, South Asian and European populations. The South Asian population had a slightly steeper slope in SAF values with age compared to other ethnic groups. All ethnic groups except Europeans showed a significant gender effect. When compared with a European group, effect size was highest for Eastern Mediterranean group and lowest for South Asian group. The Central-East African and Southeast Asian ethnicity matched closest to the Arab and Eastern Mediterranean ethnicities, respectively. Ethnic and gender-specific data improves performance in SAF-based CVD and DM risk estimation. The provided harmonized effect size allows a direct comparison of SAF in different ethnicities. For the first time, gender differences in SAF are described for North African and East Mediterranean populations.

Advanced glycation end-products (AGEs) and associations with cardio-metabolic, lifestyle, and dietary factors in a general population: the NQplus study

BACKGROUND

Advanced glycation end-products are a heterogeneous group of molecules that are formed during reactions between reducing sugars and proteins. Advanced glycation end-products are thought to play a role in several diseases, including diabetes mellitus and can be measured non-invasively using skin autofluorescence (AF). The aim of this cross-sectional study was to investigate associations between skin AF and cardio-metabolic, lifestyle, and dietary factors within a general population.

METHODS

The NQplus study is an ongoing longitudinal study in the surroundings of Wageningen, the Netherlands. In this cross-sectional study, skin AF was measured in 957 participants, aged 20 to 77 years, with the AGE Reader. Logistic regression was used to assess associations between skin AF and the following factors: demographics, adiposity, blood lipids, fasting glucose, HbA_1c , blood pressure, dietary intake, and disease history. Stepwise linear regression was used to identify factors correlating with skin AF.

RESULTS

In males, skin AF was significantly associated with age, coffee intake, systolic and diastolic blood pressure, body fat, full fat dairy, and educational level. In females, significant associations were found with age, coffee intake, HbA_1c , diabetes, and eGFR. In the total population, current smoking was positively associated with skin AF.

CONCLUSIONS

This cross-sectional study in a general population showed that age and coffee intake were associated with skin AF in both males and females. We observed a gender disparity for some of the associations with skin AF, which need to be confirmed by further research. More detailed research is needed to assess the association between skin AF and diet.

Skin advanced glycation end-products evaluation in infants according to the type of feeding and mother's smoking habits

OBJECTIVES

This study was conducted to assess whether formula-fed infants had increased skin advanced glycation end-products compared with breastfed ones. We also evaluated the effect of maternal smoke during pregnancy and lactation on infant skin advanced glycation end-products accumulation.

METHODS

Advanced glycation end-product-linked skin autofluorescence was measured in 101 infants.

RESULTS

In infants born from non-smoking mothers, advanced glycation end-products were higher in formula-fed subjects than in breastfed subjects (0.80 (0.65-0.90) vs 1.00 (0.85-1.05), p < 0.001). Advanced glycation end-products in breastfed infants from smoking mothers were higher than in those from non-smoking mothers (0.80 (0.65-0.90) vs 1.00 (0.90-1.17), p = 0.009).

CONCLUSION

Formula-fed infants had increased amounts of advanced glycation end-products compared with the breastfed ones, confirming that breast milk represents the best food for infants. Breastfed infants from mothers smoking during pregnancy and lactation had increased skin advanced glycation end-products, suggesting that smoke-related advanced glycation end-products transfer throughout breast milk. Moreover, advanced glycation end-products may already increase during gestation, possibly affecting fetal development. Thus, we reinforced that smoking must be stopped during pregnancy and lactation.

A new gender-specific model for skin autofluorescence risk stratification

Advanced glycation endproducts (AGEs) are believed to play a significant role in the pathophysiology of a variety of diseases including diabetes and cardiovascular diseases. Non-invasive skin autofluorescence (SAF) measurement serves as a proxy for tissue accumulation of AGEs. We assessed reference SAF and skin reflectance (SR) values in a Saudi population (n = 1,999) and evaluated the existing risk stratification scale. The mean SAF of the study cohort was 2.06 (SD = 0.57) arbitrary units (AU), which is considerably higher than the values reported for other populations. We show a previously unreported and significant difference in SAF values between men and women, with median (range) values of 1.77 AU (0.79-4.84 AU) and 2.20 AU (0.75-4.59 AU) respectively (p-value « 0.01). Age, presence of diabetes and BMI were the most influential variables in determining SAF values in men, whilst in female participants, SR was also highly correlated with SAF. Diabetes, hypertension and obesity all showed strong association with SAF, particularly when gender differences were taken into account. We propose an adjusted, gender-specific disease risk stratification scheme for Middle Eastern populations. SAF is a potentially valuable clinical screening tool for cardiovascular risk assessment but risk scores should take gender and ethnicity into consideration for accurate diagnosis.

The association between skin autofluorescence and vascular complications in Chinese patients with diabetic foot ulcer: an observational study done in Shanghai

The tissue accumulation of advanced glycation end products (AGEs) can be noninvasively assessed as skin autofluorescence (SAF) by the AGE Reader(TM) device. We aimed to detect the association between SAF and diabetes-associated vascular complications in diabetic foot ulcer (DFU) patients engaged in this study. This cross-sectional survey consisted of 118 consecutive hospitalized diabetic foot patients. The diabetic microvascular (retinopathy, nephropathy, and neuropathy) and macrovascular referring to coronary heart disease (CHD), cerebrovascular disease (CVD), or peripheral artery disease (PAD) complications were evaluated, and then they were divided into different subgroups based on the assessment of vascular complications. As seen from the results, the mean SAF value was 2.8 ± 0.2 AU. SAF was significantly associated with diabetes duration and blood urea nitrogen (R(2) = 62.8%; P < .01). Moreover, in logistic regression analysis, SAF was significantly associated with retinopathy (odds ratio [OR] = 40.11), nephropathy (OR = 8.44), CHD (OR = 44.31), CVD (OR = 80.73), and PAD (OR = 5.98 × 10(9)). In conclusion, SAF, reflecting tissue accumulation of AGEs, is independently associated with the presence of vascular complications in DFU patients.

25-hydroxyvitamin d and advanced glycation endproducts in healthy and hypertensive subjects: are there interactions?

Advanced glycation endproducts (AGEs) accumulate during aging. Skin is the single organ of vitamin D synthesis, induced by ultraviolet B light. Accumulation of AGEs in the skin could interfere with synthesis of the vitamin, whereas the microinflammation and oxidative stress (associated with hypovitaminosis D) could amplify both the toxic effects of AGEs and their production. Clinical data on potential interactions between vitamin D3 deficiency and AGE accumulation are sparse. Here we investigated potential associations between levels of circulating vitamin D3 and those of AGEs in blood and skin with regard to markers of inflammation and oxidative stress in nondiabetic subjects. In a cross-sectional study, 146 subjects (119 healthy persons and 27 hypertensive patients; 73 male and 73 female; mean age, 57.0 ± 15.5 years) were included. Skin autofluorescence (SAF) and plasma levels of vitamin D3, AGE-associated fluorescence, high-sensitivity C-reactive protein level, and advanced oxidation protein products as well as renal function (estimated glomerular filtration rate) were determined. In a subgroup of 61 patients, N(ε)-carboxymethyllysine, soluble receptor of AGEs, and soluble vascular adhesion protein-1 were additionally analyzed. Vitamin D3 level averaged 22.5 ± 8.9 ng/mL. Prevalence of vitamin D insufficiency (20-29 ng/mL) was 43%, and that of deficiency (<20 ng/mL) 37%. The age-dependent rise in SAF was steeper in smokers and in subjects presenting arterial hypertension. No association between SAF and hypovitaminosis D was revealed. Among smokers, an inverse relationship manifested between vitamin D3 and plasma AGE-associated fluorescence as well as soluble vascular adhesion protein-1. Our data suggest that in nondiabetic adults, hypovitaminosis D does not enhance toxicity and accumulation of AGEs. Only in smokers interactions are conceivable.

Skin Autofluorescence - A Non-invasive Measurement for Assessing Cardiovascular Risk and Risk of Diabetes

The results of the Diabetes Control and Complications Trial-Epidemiology of Diabetes Interventions and Complications (DCCT-EDIC) study have strengthened the 'glycaemic memory' concept, postulating that the quality of metabolic control over several years predicts the development of diabetic complications. To mirror long-term metabolic control, the degree of glycated haemoglobin (HbA_1c) might not represent the optimal biomarker. Other substances with a longer persistence, like the so-called advanced glycation end-products (AGEs), which probably form the substrate of the glycaemic memory, might perform better. Newly developed methods such as the assessment of skin autofluorescence (SAF), enable fast, uncomplicated and non-invasive AGEs assessment. SAF was validated for diabetes screening and shows a good predictive value for the development of diabetic and cardiovascular complications. This article deals with the theoretical background and with available clinical data on this new variable.