Correlation between serum advanced glycation end-products and vascular complications in patient with type 2 diabetes

Abstract

Advanced glycation end-products (AGEs) formation increases with metabolic disorders, leading to higher serum AGE levels in patients with progressive vascular complications. Measuring AGE levels in biological samples requires multiple pre-analytical processing steps, rendering analysis of multiple samples challenging. This study evaluated the progression of diabetic complications by analyzing AGE levels using a pre-analytical processing strategy based on a fully automated solid phase-extraction system. Serum samples from patients with diabetes, with or without macrovascular complications (Mac or non-Mac) or microvascular complications (Mic or non-Mic), were processed with the established methods. Free and total AGE levels in sera were measured using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). In patients with diabetes, both free and total AGE levels were elevated in those with complications compared to those without complications. In Mac and Mic groups, free and total AGE levels and z-scores (the sum of normalized AGE levels) also increased. AGE z-scores were markedly higher than those of single AGE levels in distinguishing each complication. Our study demonstrated that the free AGE z-score, measured using a new analytical method without hydrolysis, correlated with the presence of vascular complications and may serve as a marker of disease complications.

Keywords: Advanced glycation end-products; Healthy life expectancy; Mass spectrometry; Type 2 diabetes; Vascular complications.

Figure 1

Variations in AGEs with complications in patients with diabetes. (a) Free Lys, (b) free Arg, (c) free CML, (d) free CEL, (e) free MG-H1, (f) total Lys, (g) total Arg, (h) total CML, (i) total CEL (j) total MG-H1 levels were compared between patients without complications (without: N = 51) and with complications (with: N = 103). Data are shown with box-plot, bold horizontal bars indicating median values. Statistical analysis: Wilcoxon rank sum test; *P < 0.05; **P < 0.01; ***P < 0.001.

Figure 2

Correlation between increased AGEs and biochemical parameters in patients with diabetes. Statistical analysis: Spearman’ analysis; the significance level was set 0.05. Blue text indicates positive, while red text indicates negative correlation. FPG, fasting plasma glucose; BMI, body mass index; DM, duration of diabetes; ACR, urine albumin-creatinine ratio; TG, triglycerides; LDL, low-density lipoprotein cholesterol; HDL, high-density lipoprotein cholesterol; GGT, γ-glutamyl transpeptidase; AST, aspartate aminotransferase; ALT, alanine aminotransferase; SBP, systolic blood pressure; DBP, diastolic blood pressure; Plaque, plaque score.

Figure 3

AGE variation in macrovascular complications. (a) Free Lys, (b) free Arg, (c) free CML, (d) free CEL, (e) free MG-H1, (f) total Lys, (g) total Arg, (h) total CML, (i) total CEL (j) total MG-H1 levels were compared between non-Mac (N = 116) and Mac (N = 38). Data are shown with box-plot, bold horizontal bars indicating median values. Statistical analysis: Wilcoxon rank sum test; *P < 0.05; **P < 0.01; ***P < 0.001.

Figure 4

AGE variation in microvascular complication. (a) Free Lys, (b) free Arg, (c) free CML, (d) free CEL, (e) free MG-H1, (f) total Lys, (g) total Arg, (h) total CML, (i) total CEL (j) total MG-H1 levels were compared between non-Mic (N = 60) and Mic (N = 94). Data are shown with box-plot, bold horizontal bars indicating median values. Statistical analysis: Wilcoxon rank sum test; *P < 0.05; **P < 0.01; ***P < 0.001.

Figure 5

AGE z-scores variation in each vascular complication. (a) AGE z-score (free) between non-Mac and Mac, (b) AGE z-score (total) between non-Mac and Mac, (c) AGE z-score (free) between non-Mic and Mic were described. Data are shown with box-plot, bold horizontal bars indicating median values. Statistical analysis: Wilcoxon rank sum test; *P < 0.05; **P < 0.01; ***P < 0.001.

Figure 6

ROC curves for AGE z-scores and other parameters. (a) Free CML (orange), free CEL (yellow), free MG-H1 (lime green), total CML (green), total CEL (light green), AGE z-score (free) (light blue), AGE z-score (total) (blue), HbA1c (purple), and eGFR (pink) of ROC curves in patients with macrovascular complications were created based on the values for 154 cases. (b) Free CML (orange), free CEL (yellow), free MG-H1 (lime green), total CML (green), AGE z-score (free) (light blue), HbA1c (purple), and eGFR (pink) of ROC curve in patients with microvascular complications were created based on the values for 154 cases. AUC is presented on the graphs.