Elevated skin autofluorescence is strongly associated with foot ulcers in patients with diabetes: a cross-sectional, observational study of Chinese subjects

Role of exosome-derived miRNAs in diabetic wound angiogenesis

Chronic wounds with high disability are among the most common and serious complications of diabetes. Angiogenesis dysfunction impair wound healing in patients with diabetes. Compared with traditional therapies that can only provide symptomatic treatment, stem cells-owing to their powerful paracrine properties, can alleviate the pathogenesis of chronic diabetic wounds and even cure them. Exosome-derived microRNAs (miRNAs), important components of stem cell paracrine signaling, have been reported for therapeutic use in various disease models, including diabetic wounds. Exosome-derived miRNAs have been widely reported to be involved in regulating vascular function and have promising applications in the repair and regeneration of skin wounds. Therefore, this article aims to review the current status of the pathophysiology of exosome-derived miRNAs in the diabetes-induced impairment of wound healing, along with current knowledge of the underlying mechanisms, emphasizing the regulatory mechanism of angiogenesis, we hope to document the emerging theoretical basis for improving wound repair by restoring angiogenesis in diabetes.

The skin autofluorescence of advanced glycation end-products relates to the development of foot ulcers in type 2 diabetes: A longitudinal observational study

OBJECTIVES

The long-term glycemic memory contributes to vascular complications in type 2 diabetes, including those patients with Diabetic Foot Ulcers (DFU). We investigated whether the skin autofluorescence (SAF) of Advanced Glycation End-products related to later DFUs.

RESEARCH DESIGN & METHODS

SAF was measured with an AGE-Reader in a retrospective cohort of patients hospitalized from 2009 to 2017 for Type 2 Diabetes. New DFUs were registered until the year 2020 and survival analyses were performed.

RESULTS

The 517 patients (men: 58.0 %), were 62 ± 9 years old at baseline, with a duration of diabetes of 14 ± 10 years, HbA1c: 8.7 ± 1.8 %, complications included 33.8 % macroangiopathies, 44.9 % diabetic kidney diseases and 26.7 % retinopathies. According to the IWGDF classification, the grades of risk for DFU were 0 for 43.2 %, 1 for 23.9 %, 2 for 7.2 %, and 3 for 25.7 %. During the 53 months of follow-up, 58 new DFUs occurred, mostly in patients with SAF higher than its median value (2.65 AU). Adjusted for age and sex, conventional risk factors (duration and control of diabetes, arterial hypertension, dyslipidemia, smoking), and other complications (macroangiopathy, diabetic kidney disease, retinopathy), SAF related to later DFUs. Adjusted for the IWGDF classification, SAF related to new DFUs (HR: 1.81, 95%CI:1.25-2.62). This relationship was significant for the 403 subjects without previous history of DFU (HR: 2.32, 95%CI: 1.36-3.95). SAF did not predict recurrence for patients with a previous history of DFUs.

CONCLUSION

SAF, a simple non-invasive marker of glycemic memory, independently predicts the occurrence of a first foot ulcer in patients with Type 2 Diabetes.

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.

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.

Skin Autofluorescence as a Novel and Noninvasive Technology for Advanced Glycation End Products in Diabetic Foot Ulcers: A Systematic Review and Meta-analysis

OBJECTIVE

Skin autofluorescence (SAF) has been suggested as a novel and noninvasive technique for assessing tissue accumulation of advanced glycation end products in diabetes and related complications. The aim of this systematic review and meta-analysis was to evaluate the use of SAF in diabetic foot ulcers (DFUs).

DATA SOURCES

PubMed/MEDLINE and other digital databases.

STUDY SELECTION

The authors included studies comparing the SAF levels in patients with DFU with a non-DFU group to determine its association with DFU risk.

DATA EXTRACTION

Collected data included the SAF method and its values in DFU and non-DFU groups, covariates used in adjustment along with the unadjusted and/or multivariate adjusted odds ratios (ORs) for the association of SAF with DFU risk, and other study characteristics.

DATA SYNTHESIS

A total of six studies were included in this meta-analysis. Five studies that involved 611 participants were included to compare SAF methods. Compared with the non-DFU group, the DFU group showed a significantly increased level of SAF (standardized mean difference, 0.67; 95% confidence interval [CI], 0.32-1.01; P < .001). The results of meta-analysis of ORs revealed that the increased SAF level was independently associated with increased DFU risk in both unadjusted (OR, 3.16; 95% CI, 2.18-4.57; P < .001) and adjusted models (OR, 3.07; 95% CI, 1.95-4.81; P < .001).

CONCLUSIONS

These findings suggest that SAF could be useful as a novel and noninvasive technology to help determine DFU risk. However, further studies establishing its diagnostic and prognostic utilities are needed.

Diabetic foot complications-lessons learned from real-world data derived from a specialized Austrian hospital

BACKGROUND

Diabetic foot complications, one of the most severe late complications of type 2 diabetes mellitus, are associated with a tremendous personal and financial burden. In order to drive the prevention of diabetic foot complications forward and facilitate early detection and personalized screening of high-risk patients, longitudinal studies are needed to identify risk factors associated with diabetic foot complications in large patient datasets.

METHODS

This is a retrospective cohort study on 3002 patients with type 2 diabetes mellitus aged ≥ 18 years without prior foot complications. The data were collected between 2006 and 2017 in an Austrian hospital department specialized for diabetic patients. In addition to a univariate Cox regression analysis, multivariate Cox regression models were established to identify independent risk factors associated with diabetic foot complications and adjust for potential confounders.

RESULTS

We observed a total of 61 diabetic foot complications in 3002 patients. In the multivariate Cox regression model, significant risk factors (hazard ratio, 95% confidence interval) for foot complications were age at diagnosis > 70 years (3.39, 1.33-8.67), male gender (2.55, 1.42-4.55), neuropathy (3.03, 1.74-5.27), peripheral arterial disease (3.04, 1.61-5.74), hypertension > 10 years after diagnosis (2.32, 1.09-4.93) and HbA1c > 9% (2.44, 1.02-5.83).

CONCLUSION

The identified risk factors for diabetic foot complications suggest that personalized early detection of patients at high risk might be possible by taking the patient's clinical characteristics, medical history and comorbidities into account. Modifiable risk factors, such as hypertension and high levels of blood glucose might be tackled to reduce the risk for diabetic foot complications.

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 AGEs and diabetic neuropathy

Advanced glycation end-products (AGEs) are heterogeneous molecules produced by the non-enzymatic glycation of proteins, lipids, or nucleic acids during hyperglycaemia. Accumulation of AGEs in the peripheral nerves has recently been proposed as an additional risk factor for the development of diabetic neuropathy (DN). The gold standard for measurement of tissue-bound AGEs is tissue biopsy. However, their assessment with the newer, fast and simple method of skin autofluorescence (sAF) has recently gained special interest by virtue of its non-invasive, highly reproducible nature and its acceptable correlation with the reference method of skin biopsy. Accumulation of tissue AGEs evaluated by sAF has been shown to independently correlate with DN. Importantly, increasing evidence underscores their potential value as early biomarkers of the latter. Further important associations include diabetic nephropathy, diabetic retinopathy and cardiovascular autonomic neuropathy. However, the value of the implementation of screening with skin AGEs for DN remains unclear. The aim of the present review is to critically summarise current evidence on the association between skin AGEs and diabetic microvascular complications, with a particular emphasis on diabetic neuropathy, and to note the most important limitations of existing knowledge. Longer follow-up studies are also highly anticipated to clarify its role and provide data on patient selection and cost-effectiveness.

Attenuation of methylglyoxal-induced glycation and cellular dysfunction in wound healing by Centella cordifolia

Current pre-clinical evidences of Centella focus on its pharmacological effects on normal wound healing but there are limited studies on the bioactivity of Centella in cellular dysfunction associated with diabetic wounds. Hence we planned to examine the potential of Centella cordifolia in inhibiting methylglyoxal (MGO)-induced extracellular matrix (ECM) glycation and promoting the related cellular functions. A Cell-ECM adhesion assay examined the ECM glycation induced by MGO. Different cell types that contribute to the healing process (fibroblasts, keratinocytes and endothelial cells) were evaluated for their ability to adhere to the glycated ECM. Methanolic extract of Centella species was prepared and partitioned to yield different solvent fractions which were further analysed by high performance liquid chromatography equipped with photodiode array detector (HPLC-PDA) method. Based on the antioxidant [2,2-diphenyl-1-picrylhydrazyl (DPPH) assay] screening, anti-glycation activity and total phenolic content (TPC) of the different Centella species and fractions, the ethyl acetate fraction of C. cordifolia was selected for further investigating its ability to inhibit MGO-induced ECM glycation and promote cellular distribution and adhesion. Out of the three Centella species (C. asiatica, C. cordifolia and C. erecta), the methanolic extract of C. cordifolia showed maximum inhibition of Advanced glycation end products (AGE) fluorescence (20.20 ± 4.69 %, 25.00 ± 3.58 % and 16.18 ± 1.40 %, respectively). Its ethyl acetate fraction was enriched with phenolic compounds (3.91 ± 0.12 mg CAE/μg fraction) and showed strong antioxidant (59.95 ± 7.18 μM TE/μg fraction) and antiglycation activities. Improvement of cells spreading and adhesion of endothelial cells, fibroblasts and keratinocytes was observed for ethyl acetate treated MGO-glycated extracellular matrix. Significant reduction in attachment capacity of EA.hy926 cells seeded on MGO-glycated fibronectin (41.2%) and attachment reduction of NIH3t3 and HaCaT cells seeded on MGO-glycated collagen (33.7% and 24.1%, respectively) were observed. Our findings demonstrate that ethyl acetate fraction of C. cordifolia was effective in attenuating MGO-induced glycation and cellular dysfunction in the in-vitro wound healing models suggesting that C. cordifolia could be a potential candidate for diabetic wound healing. It could be subjected for further isolation of new phytoconstituents having potential diabetic wound healing properties.

Skin Advanced Glycation End Products among Subjects with Type 2 Diabetes Mellitus with or without Distal Sensorimotor Polyneuropathy

MATERIALS AND METHODS

We included 132 subjects (88 men) with a mean age of 64.57 years and median T2DM duration of 14.5 years. Skin AGEs were measured with AGE reader mu connect (Diagnoptics) on the dominant arm. The device enables single and automated triplicate measurements: both of these were performed. DSPN was diagnosed through the neuropathy disability score (NDS). Small nerve fibre function was assessed by temperature and pinprick sensation on the foot. Bilateral measurement of the vibration perception threshold (VPT) on the hallux was carried out by using a neurothesiometer (Horwell Scientific Laboratory Supplies).

RESULTS

Single and triplicate AGE measurements were positively correlated with each other (Pearson's correlation coefficient r = 0.991, 95%CI = 0.987-0.994, p < 0.001). AGEs were higher among subjects with vs. those without DSPN (p < 0.001). Furthermore, they were higher among subjects with reduced vs. normal temperature sensation (p < 0.001), among subjects with reduced vs. normal pinprick sensation (p = 0.002), among those with abnormal vs. normal monofilament examination (p < 0.001), and among those with abnormal vs. normal VPT (p < 0.001). AGEs were correlated with NDS, VPT, and monofilament score.

CONCLUSIONS

In T2DM, skin AGEs are increased in the presence of DSPN. This holds true both for large and for small nerve function impairment. Moreover, AGEs are correlated with DSPN severity.

Risk factors for diabetic foot complications in type 2 diabetes-A systematic review

Aims

With increasing numbers of patients with type 2 diabetes mellitus (T2DM) worldwide, the number of associated diabetic foot complications might also increase. This systematic review was performed to summarize published data about risk factors for the diabetic foot (DF) syndrome in order to improve the identification of high-risk patients.

Materials and methods

Six electronic databases were searched for publications up to August 2019 using predefined stringent inclusion and exclusion criteria.

Results

Of 9,476 identified articles, 31 articles from 28 different study populations fulfilled the criteria for our evaluation. The overall quality of the studies was good, and the risk of bias was low. There was large heterogeneity among the studies concerning study protocols and patient populations analysed. A total of 79 risk factors were analysed within this review. The majority of studies described a consistently positive association with different outcomes of interest related to DF for gender, peripheral neuropathy, retinopathy, nephropathy, poor glycaemic control, insulin use, duration of diabetes, smoking and height. For age, hypertension, dyslipidaemia and body mass index, the results remain inconsistent.

Conclusion

A most up-to-date literature review resulted in glycaemic control and smoking as the only amenable risk factors with a consistently positive association for DF. Due to the high personal and financial burden associated with DF and the large heterogeneity among included studies, additional longitudinal studies in large patient populations are necessary to identify more modifiable risk factors that can be used in the prediction and prevention of DF complications.

Is skin autofluorescence (SAF) representative of dermal advanced glycation endproducts (AGEs) in dark skin? A pilot study

Aims

Non-invasively assessed skin autofluorescence (SAF) measures advanced glycation endproducts (AGEs) in the dermis. SAF correlates with dermal AGEs in Caucasians and Asians, but studies in dark-skinned subjects are lacking. In this pilot we aimed to assess whether SAF signal is representative of intrinsic fluorescence (IF) and AGE accumulation in dark skin.

Methods

Skin biopsies were obtained in 12 dark-skinned subjects (6 healthy subjects, median age 22 years; 6 diabetes mellitus (DM) subjects, 65 years). SAF was measured with the AGE Reader, IF using confocal microscopy, and AGE distribution with specific antibodies. CML and MG-H1 were quantified with UPLC-MS/MS and pentosidine with HPLC and fluorescent detection.

Results

SAF correlated with IF from the dermis (405nm, r = 0.58, p < 0.05), but not with CML (r = 0.54, p = 0.07). CML correlated with IF from the dermis (405nm, r = 0.90, p < 0.01). UV reflectance and the coefficient of variation of SAF were negatively correlated (r = -0.80, p < 0.01). CML and MG-H1 were predominantly present around blood vessels, in collagen and fibroblasts in the dermis.

Conclusion

This proof of concept study is the first to compare non-invasive SAF with AGE levels measured in skin biopsies in dark-skinned subjects. SAF did not correlate with individual AGEs from biopsies, but was associated with IF. However, the intra-individual variance was high, limiting its application in dark-skinned subjects on an individual basis.

Skin autofluorescence, a marker of glucose memory in type 2 diabetes

Abstract

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The accumulation of Advanced Glycation End-products in the tissues studied as a marker of metabolic memory.

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Skin autofluorescence as a marker of glycemic memory in type 2 diabetes.

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Skin autofluorescence was independently related to their most ancient HbA1c.

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Skin autofluorescence was higher in subjects with microangiopathic complications.

Within- and Between-Body-Site Agreement of Skin Autofluorescence Measurements in People With and Without Diabetes-Related Foot Disease

BACKGROUND

Skin autofluorescence has been used to assess longer term glycemic control and risk of complications. There is however no agreed site at which autofluorescence should be measured. This study evaluated the within- and between-site agreement in measurement of skin autofluorescence using a noninvasive advanced glycation end product (AGE) reader.

METHODS

Overall, 132 participants were included: 16 with diabetes-related foot ulcers (DFU), 63 with diabetes but without foot ulcers (DMC), 53 without diabetes or foot ulcers (HC). Skin autofluorescence was measured using the AGE Reader (DiagnOptics technologies BV, the Netherlands). Three consecutive skin autofluorescence measurements were each performed at six different body sites: the volar surfaces of both forearms (arms), dorsal surfaces of both calves (legs), and plantar surfaces of both feet (feet). Within- and between-site agreements were analyzed with concordance correlation coefficients (CCC) and 95% confidence intervals (95% CI), absolute mean differences (±standard deviation), and Bland-Altman limits of agreement.

RESULTS

The agreement between repeat assessments at the same site was almost perfect (CCC [95% CI] ranging from 0.94 [0.91-0.96] for assessments in the right foot to 0.99 [0.99-0.99] for assessments in the left arm). The limits of agreement were narrow within ±0.5 arbitrary units for all sites. The between-site agreement in measurements was poor (CCC < 0.65) with large maximum absolute mean differences (±SD) in arbitrary units (DFU = 3.40 [±2.04]; DMC = 3.15 [±2.45]; HC = 2.72 [±1.83]) and wide limits of agreement.

CONCLUSIONS

Skin autofluorescence measurements can be repeated at the same site with adequate repeatability but measurements at different sites in the same patient have marked differences. The reason for this variation across sites and whether this has any role in diabetes-related complications needs further investigation.

Arterial stiffness alone does not explain arteriovenous fistula outcomes

INTRODUCTION

Marked arterial adaptation is critical in permitting and sustaining the increased blood flow within an arteriovenous fistula (AVF). The aim of this investigation was to evaluate markers of arterial disease and their association with the early post-operative AVF outcomes.

METHODS

We included all patients in whom an AVF had been performed after enrolment to the Renal Impairment In Secondary Care (RIISC) study. Primary AVF failure (PFL) was defined as thrombosis at six-week review. All patients underwent BP Tru and Vicorder pulse wave analysis assessments and also had assays of advanced glycation end-products prior to AVF formation. These were correlated with the short-term AVF outcomes.

RESULTS

One hundred and eight AVFs were created in 86 patients. The primary patency (PPT) group were found to have significantly higher body mass index (BMI) (p = 0.01). Intraluminal vein diameter was significantly greater in the PPT group than the PFL group (p≤0.01). Mean augmentation index and augmentation index 75 was significantly higher in the PPT group than the PFL group (p = 0.03 and 0.03, respectively). Aortic pulse wave velocity was slower in the PPT group at 10.2 m/s than the PFL group at 10.8 m/s (p = 0.32). Advanced glycation end-product measurements did not vary significantly between the PPT and PFL groups (p = 0.4). Logistic regression analysis provided a predictive model, which demonstrated a predictive value of 78.1% for AVF patency at 6 weeks.

CONCLUSIONS

All patients in this end-stage renal disease cohort have significant aortic stiffness. The results for pulse wave velocity were slower in the PPT group suggesting a tendency towards stiffer vessels and PFL.

Global epidemiology of diabetic foot ulceration: a systematic review and meta-analysis †

Diabetic foot is a severe public health issue, yet rare studies investigated its global epidemiology. Here we performed a systematic review and meta-analysis through searching PubMed, EMBASE, ISI Web of science, and Cochrane database. We found that that global diabetic foot ulcer prevalence was 6.3% (95%CI: 5.4-7.3%), which was higher in males (4.5%, 95%CI: 3.7-5.2%) than in females (3.5%, 95%CI: 2.8-4.2%), and higher in type 2 diabetic patients (6.4%, 95%CI: 4.6-8.1%) than in type 1 diabetics (5.5%, 95%CI: 3.2-7.7%). North America had the highest prevalence (13.0%, 95%CI: 10.0-15.9%), Oceania had the lowest (3.0%, 95% CI: 0.9-5.0%), and the prevalence in Asia, Europe, and Africa were 5.5% (95%CI: 4.6-6.4%), 5.1% (95%CI: 4.1-6.0%), and 7.2% (95%CI: 5.1-9.3%), respectively. Australia has the lowest (1.5%, 95%CI: 0.7-2.4%) and Belgium has the highest prevalence (16.6%, 95%CI: 10.7-22.4%), followed by Canada (14.8%, 95%CI: 9.4-20.1%) and USA (13.0%, 95%CI: 8.3-17.7%). The patients with diabetic foot ulcer were older, had a lower body mass index, longer diabetic duration, and had more hypertension, diabetic retinopathy, and smoking history than patients without diabetic foot ulceration. Our results provide suggestions for policy makers in deciding preventing strategy of diabetic foot ulceration in the future. Key messages Global prevalence of diabetic foot is 6.3% (95%CI: 5.4-7.3%), and the prevalence in North America, Asia, Europe, Africa and Oceania was 13.0% (95%CI: 10.0-15.9%), 5.5% (95%CI: 4.6-6.4%), 5.1% (95%CI: 4.1-6.0%), 7.2% (95%CI: 5.1-9.3%), and 3.0% (95% CI: 0.9-5.0%). Diabetic foot was more prevalent in males than in females, and more prevalent in type 2 diabetic foot patients than in type 1 diabetic foot patients. The patients with diabetic foot were older, had a lower body mass index, longer diabetic duration, and had more hypertension, diabetic retinopathy, and smoking history than patients without diabetic foot.

Skin autofluorescence and peripheral neuropathy four years later in type 1 diabetes

OBJECTIVE

Advanced glycation end products (AGEs) are involved in diabetes complications. We aimed to investigate whether the accumulation of AGEs measured by skin autofluorescence (sAF) was associated with signs of diabetic peripheral neuropathy and to sensitivity, pain, motor and autonomic function 4 years later in patients with type 1 diabetes.

METHODS

At baseline, 188 patients (age 51 years, diabetes duration 22 years) underwent skin autofluorescence measurement using the AGE Reader. Four years later, signs of diabetic peripheral neuropathy were defined as the presence of neuropathic pain and/or feet sensory loss or foot ulceration. Neurological tests were systematically performed: vibration perception threshold by neuroesthesiometry, neuropathic pain by the Douleur Neuropathique en 4 Questions score, muscle strength by dynamometry and electrochemical skin conductance. Multivariate analyses were adjusted by age, sex, height, body mass index, tobacco, HbA_1c , diabetes duration, estimated glomerular filtration rate and albumin excretion rate.

RESULTS

At the 4-year follow-up, 13.8% of patients had signs of diabetic peripheral neuropathy. The baseline sAF was higher in those with signs of diabetic peripheral neuropathy (2.5 ± 0.7 vs 2.1 ± 0.5 arbitrary units (AU), p < 0.0005). In the multivariate analysis, a 1 SD higher skin autofluorescence at baseline was associated with an increased risk of signs of neuropathy (OR = 2.68, p = 0.01). All of the neurological tests were significantly altered in the highest quartile of the baseline sAF (>2.4 AU) compared with the lowest quartiles after multivariate adjustment.

CONCLUSION

This non-invasive measurement of skin autofluorescence may have a value for diabetic peripheral neuropathy in type 1 diabetes and a potential clinical utility for detection of diabetic peripheral neuropathy. Copyright © 2016 John Wiley & Sons, Ltd.

Skin collagen fluorophore LW-1 versus skin fluorescence as markers for the long-term progression of subclinical macrovascular disease in type 1 diabetes

BACKGROUND

Skin collagen Long Wavelength Fluorescence (LWF) is widely used as a surrogate marker for accumulation of advanced glycation end-products. Here we determined the relationship of LWF with glycemia, skin fluorescence, and the progression of complications during EDIC in 216 participants from the DCCT.

METHODS

LW-1 and collagen-linked fluorescence (CLF) were measured by either High Performance Liquid Chromatography (HPLC) with fluorescence detection (LW-1) or total fluorescence of collagenase digests (CLF) in insoluble skin collagen extracted from skin biopsies obtained at the end of the DCCT (1993). Skin intrinsic fluorescence (SIF) was noninvasively measured on volar forearm skin at EDIC year 16 by the SCOUT DS instrument.

RESULTS

LW-1 levels significantly increased with age and diabetes duration (P < 0.0001) and significantly decreased by intensive vs. conventional glycemic therapy in both the primary (P < 0.0001) and secondary (P < 0.037) DCCT cohorts. Levels were associated with 13-16 year progression risk of retinopathy (>3 sustained microaneurysms, P = 0.0004) and albumin excretion rate (P = 0.0038), the latter despite adjustment for HbA1c. Comparative analysis for all three fluorescent measures for future risk of subclinical macrovascular disease revealed the following significant (P < 0.05) associations after adjusting for age, diabetes duration and HbA1c: coronary artery calcium with SIF and CLF; intima-media thickness with SIF and LW-1; and left ventricular mass with LW-1 and CLF.

CONCLUSIONS

LW-1 is a novel risk marker that is robustly and independently associated with the future progression of microvascular disease, intima-media thickness and left ventricular mass in type 1 diabetes. Trial registration NCT00360815 and NCT00360893 at clinicaltrials.gov.

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.

AGEs and chronic subclinical inflammation in diabetes: disorders of immune system

Chronic subclinical inflammation represents a risk factor of type 2 diabetes and several diabetes complications, including neuropathy and atherosclerosis including macro-vasculopathy and micro-vasculopathy. However, the inflammatory response in the diabetic wound was shown to be remarkably hypocellular, unregulated and ineffective. Advanced glycation end products (AGEs) and one of its receptors, RAGE, were involved in inducing chronic immune imbalance in diabetic patients. Such interactions attracts immune cell into diffused glycated tissue and activates these cells to induce inflammatory damage, but disturbs the normal immune rhythm in diabetic wound. Traditional measurements of AGEs are high-performance liquid chromatography and immunohistochemistry staining, but their application faces the limitations including complexity, cost and lack of reproducibility. A new noninvasive method emerged in 2004, using skin autofluorescence as indicator for AGEs accumulation. It had been reported to be informative in evaluating the chronic risk of diabetic patients. Studies have indicated therapeutic potentials of anti-AGE recipes. These recipes can reduce AGE absorption/de novo formation, block AGE-RAGE interaction and arrest downstream signaling after RAGE activation.

Autofluorescence of Skin Advanced Glycation End Products: Marker of Metabolic Memory in Elderly Population

BACKGROUND

Advanced glycation end products are involved in the vascular complications of diabetes, in chronic kidney disease, and in the aging process. Their accumulation in the elderly people, as reflected by skin autofluorescence (sAF), may be a marker of metabolic memory. We aimed to examine the association of sAF with glycemic and renal status 10 years earlier in older persons.

METHODS

In retrospective cohort study, 328 elderly community dwellers aged of 75 years and over had sAF measurement 10 years after their inclusion in the Three-City cohort. Fasting plasma glucose and serum creatinine were measured at baseline and at 10-year follow-up. In 125 participants, HbA1c was available at these two times. Associations between sAF and the glycemic and renal status 10 years before were analyzed by multivariate linear regression adjusted for age, sex, hypertension, body mass index, hypertriglyceridemia, and smoking.

RESULTS

Participants were 82.4 (standard deviation = 4.1) years on average, and their mean sAF was 2.8 (standard deviation = 0.7) arbitrary units (AU). After adjustment, sAF was higher in participants with long-standing diabetes (+0.38 AU, p = .01) or chronic kidney disease (+0.29 AU, p = .02) compared with healthy participants. sAF was related to fasting plasma glucose (+1 mmol/L associated with +0.08 AU, p = .01) and HbA1c (+1% associated with +0.15 AU, p = .03) 10 years earlier, but not to the current fasting plasma glucose (p = .82) and HbA1c (p = .32). sAF was also related to the distal and current estimated glomerular filtration rates (p = .002 and .004, respectively).

CONCLUSIONS

sAF reflects glycemic and renal status 10 years before, supporting its value as a marker of metabolic memory in the elderly people.

Advanced glycation end products assessed by skin autofluorescence: a new marker of diabetic foot ulceration

BACKGROUND

Accumulation of advanced glycation end products (AGEs) may contribute to diabetic foot ulceration (DFU). Our goal was to determine whether AGEs measurement by skin autofluorescence (SAF) would be an additional marker for DFU management.

PATIENTS AND METHODS

We performed SAF analysis in 66 patients with a history of DFU prospectively included and compared the results with those of 84 control patients with diabetic peripheral neuropathy without DFU. We then assessed the prognostic value of SAF levels on the healing rate in the DFU group.

RESULTS

Mean SAF value was significantly higher in the DFU group in comparison with the control group, even after adjustment for other diabetes complications (3.2±0.6 arbitrary units vs. 2.9±0.6 arbitrary units; P=0.001). In the DFU group, 58 (88%) patients had an active wound at inclusion. The mean DFU duration was 14±13 weeks. The healing rate was 47% after 2 months of appropriate foot care. A trend for a correlation between SAF levels and healing time in DFU subjects was observed but was not statistically significant (P=0.06).

CONCLUSIONS

Increased SAF levels are associated with neuropathic foot complications in diabetes. Use of SAF measurement to assess foot vulnerability and to predict DFU events in high-risk patients appears to be promising.

Skin autofluorescence measurement in diabetological and nephrological clinical practice

Formation of advanced glycation end-products plays role in the pathogenesis of diabetic complications and related ongoing connective tissue degeneration as part of atherosclerosis and chronic kidney disease. The cumulative metabolic burden of patients can be measured in few minutes using a recently developed non-invasive mobile device, which has been developed for the evaluation of fluorescent advanced glycation end-product molecules in skin. The variation of skin autofluorescence measurement is about 10%, and its predictive value in cardiovascular events overcomes conventional glycemic markers even in chronic kidney disease population. In the early stages of diabetes it seems to be an effective screening tool, and in overt diabetes signifies micro- and macrovascular complications. This method is unadaptable in systemic autoimmune diseases, generalised dermatological illnesses and hepatobiliary pathological conditions leading to icterus. Significant correlation has been found between skin autofluorescence and pulse wave velocity due to glycation of vascular wall structure proteins and consequent arterial matrix rigidity. Orv. Hetil., 2012, 153, 1651–1657.