Serum Levels of Advanced Glycation End Products (AGEs) are Independent Correlates of Insulin Resistance in Nondiabetic Subjects

Background: Advanced glycation end products (AGEs) evoke oxidative stress generation and inflammatory reactions, thus being involved in vascular complications in diabetes. Since oxidative stress and inflammation impair insulin actions as well, it is conceivable that AGEs may play some role in insulin resistance. However, there is no clinical study to examine the relationship between serum levels of AGEs and insulin resistance. This study investigated whether serum AGE levels were independent correlates of insulin resistance in humans. Methods: Three hundred twenty-two nondiabetic Japanese subjects (216 male and 106 female; mean age 61.5 +/- 9.1 years) underwent a complete history and physical examination, determinations of blood chemistries, anthropometric and metabolic variables, including AGEs. Serum AGE levels were examined with an enzyme-linked immunosorbent assay. Results: Mean serum AGE levels were 8.96 +/- 2.57 U/mL. In univariate analysis, waist circumference, diastolic blood pressure (BP), mean BP, AGEs, low-density lipoprotein (LDL) cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol (inversely), hemoglobin A1c (GHb), creatinine clearance, uric acid, and high sensitivity C-reactive protein were significantly associated with insulin resistance evaluated by homeostasis model assessment of insulin resistance (HOMA-IR) index. After performing multiple regression analysis, waist circumference (P < 0.001), GHb (P < 0.001), triglycerides (P < 0.001), and AGEs (P < 0.01) still remained significant independently. When age-adjusted HOMA-IR levels stratified by AGE tertiles were compared using ANCOVA, a significant trend was demonstrated in both males and females. Conclusion: The present study demonstrated for the first time that serum AGE levels were one of the independent correlates of HOMA-IR index, thus suggesting that AGEs may play some pathological role in insulin resistance in humans.