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

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.

Associations between Skin Autofluorescence Levels with Cardiovascular Risk and Diabetes Complications in Patients with Type 2 Diabetes

Advanced Glycation End Products (AGEs) contribute to the pathophysiology of type 2 diabetes mellitus (T2DM) and cardiovascular (CV) diseases (CVDs), making their non-invasive assessment through skin autofluorescence (SAF) increasingly important. This study aims to investigate the relationship between SAF levels, cardiovascular risk, and diabetic complications in T2DM patients. We conducted a single-center, cross-sectional study at Consultmed Hospital in Iasi, Romania, including 885 T2DM patients. The assessment of SAF levels was performed with the AGE Reader™, (Diagnoptics, Groningen, The Netherlands). CVD prevalence was 13.9%, and according to CV risk category distribution, 6.1% fell into the moderate-risk, 1.13% into the high-risk, and 92.77% into the very-high-risk category. The duration of DM averaged 9.0 ± 4.4 years and the mean HbA1c was 7.1% ± 1.3. After adjusting for age and eGFR, HbA1c values showed a correlation with SAF levels in the multivariate regression model, where a 1 SD increase in HbA1c was associated with a 0.105 SD increase in SAF levels (Nagelkerke R2 = 0.110; p < 0.001). For predicting very high risk with an SAF cut-off of 2.35, sensitivity was 67.7% and specificity was 56.2%, with an AUC of 0.634 (95% CI 0.560-0.709, p = 0.001). In T2DM, elevated SAF levels were associated with higher CV risk and HbA1c values, with 2.35 identified as the optimal SAF cut-off for very high CV risk.

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.

Clinical significance of skin autofluorescence for diabetic macroangiopathy and comparison with conventional markers of atherosclerosis: a cross-sectional and prospective study

Background

Skin autofluorescence (SAF) is a marker for the accumulation of advanced glycation end products (AGEs), and is associated with diabetic macroangiopathy. However, whether SAF is superior to conventional markers of atherosclerosis such as carotid intima-media thickness (IMT) and pulse wave velocity (PWV) in detecting macroangiopathy remains unclear.

Methods

We recruited 845 patients with type 2 diabetes enrolled in a community diabetes cohort (ViNA cohort) who had SAF, IMT, and PWV measured at baseline. The prevalence of macroangiopathy at baseline and new cardiovascular events during the 2-year follow-up period was investigated. SAF was measured using an AGE reader. Coronary artery calcification (CAC) was measured by computed tomography in 485 patients. Peripheral artery disease (PAD) was defined as the ankle-brachial blood pressure ratio of ≤ 0.9.

Results

SAF, IMT, and PWV were significantly correlated with each other, and age, diabetes duration, and estimated glomerular filtration rate were their strong confounders. SAF was associated with baseline stroke and new stroke after adjusting for confounders, but not with coronary artery disease (CAD) or PAD. The nonsignificant relationship between SAF and CAD was consistent with the relationship between SAF and CAC. Multivariate analysis showed a significant association of SAF with baseline and new stroke independent of IMT and PWV. Maximum-IMT was significantly associated with baseline CAD, PAD, and stroke, but not with a new stroke, whereas PWV was associated with a new stroke.

Conclusion

Among diabetic macroangiopathies, SAF is a good stroke biomarker, but not for CAD and PAD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-022-00608-8.

Skin Autofluorescence Measurement as Initial Assessment of Hepatic Parenchyma Quality in Patients Undergoing Liver Resection

Skin autofluorescence (SAF) can detect advanced glycation end products (AGEs) that accumulate in tissues over time. AGEs reflect patients’ general health, and their pathological accumulation has been associated with various diseases. This study aimed to determine whether its measurements can correlate with the liver parenchyma quality. This prospective study included 186 patients who underwent liver resections. Liver fibrosis and/or steatosis > 10% were found in almost 30% of the patients. ROC analysis for SAF revealed the optimal cutoff point of 2.4 AU as an independent predictor for macrovesicular steatosis ≥ 10% with an AUC of 0.629 (95% CI 0.538−0.721, p = 0.006), 59.9% sensitivity, 62.4% specificity, and positive (PPV) and negative (NPV) predictive values of 45.7% and 74.1%, respectively. The optimal cutoff point for liver fibrosis was 2.3 AU with an AUC of 0.613 (95% CI 0.519−0.708, p = 0.018), 67.3% sensitivity, 55.2% specificity, and PPV and NPV of 37.1% and 81.2%, respectively. In the multivariable logistic regression model, SAF ≥ 2.4 AU (OR 2.16; 95% CI 1.05−4.43; p = 0.036) and BMI (OR 1.21; 95% CI 1.10−1.33, p < 0.001) were independent predictors of macrovesicular steatosis ≥ 10%. SAF may enhance the available non-invasive methods of detecting hepatic steatosis and fibrosis in patients prior to liver resection.

Advanced Glycations End Products in the Skin as Biomarkers of Cardiovascular Risk in Type 2 Diabetes

The incidence and prevalence of diabetes are increasing worldwide, and cardiovascular disease (CVD) is the leading cause of death among subjects with type 2 diabetes (T2D). The assessment and stratification of cardiovascular risk in subjects with T2D is a challenge. Advanced glycation end products are heterogeneous molecules produced by non-enzymatic glycation of proteins, lipids, or nucleic acids. Accumulation of advanced glycation end products is increased in subjects with T2D and is considered to be one of the major pathogenic mechanism in developing complications in diabetes. Skin AGEs could be assessed by skin autofluorescence. This method has been validated and related to the presence of micro and macroangiopathy in individuals with type 2 diabetes. In this context, the aim of this review is to critically summarize current knowledge and scientific evidence on the relationship between skin AGEs and CVD in subjects with type 2 diabetes, with a brief reference to other diabetes-related complications.