Utility of Tetrahydrobiopterin Pathway in the Assessment of Diabetic Foot Ulcer: Significant and Complex Interrelations

Neopterin in the Evolution from Obesity to Prediabetes and Newly Diagnosed Type 2 Diabetes

Background: Neopterin, marker of cellular immunity and oxidative stress, is mainly produced by activated macrophages. It could play a crucial role in the development of insulin resistance (IR) and type 2 diabetes (T2D). The aim of this study was to investigate the circulating levels of neopterin in different stages of glucose dysregulation from obesity through prediabetes to newly diagnosed diabetes. Methods: Neopterin levels were determined using a commercially available human enzyme-linked immunosorbent assay kit. The homeostasis model assessment of IR was used as an index to assess IR. Results: The sample consisted of 163 subjects with mean age 52.5 ± 11.3 years, divided in three age- and body mass index (BMI)-matched groups-obesity, prediabetes, and diabetes. The control group consisted of 42 healthy individuals. Neopterin levels were significantly higher in patients with obesity and/or prediabetes and newly diagnosed diabetes than those in the control group, respectively (4.14 ± 2.51; 4.04 ± 2.80 and 2.17 ± 1.93 vs. 0.87 ± 0.84; P < 0.05). Correlation analysis showed that the level of neopterin positively correlated with BMI, waist, waist-to-stature ratio, waist-to-hip ratio, fasting glucose, and triglycerides. Receiver operating characteristic analysis established neopterin suitable for distinguishing subjects with obesity [area under the curve (AUC) = 0.83; P < 0.001] and carbohydrate disturbances (AUC = 0.59; P < 0.05) from those without these conditions. Neopterin ≥0.47 ng/mL have an odds ratio (OR) of 2.71 for development of dysglycemia, whereas threshold value of neopterin ≥0.56 ng/mL shows an OR of 5.94 for development of obesity. Conclusion: The levels of neopterin were increased in patients with obesity and carbohydrate disturbances. Further studies will elucidate the role of the biomarker in development of T2D and its complications.