TABLE 2.
Summary of published studies on blood metabolomics of diabetic retinopathy.
| Authors | Year | Platform | Matching | Case | Control | Patients | Biomarker (up) | Biomarker (down) | Pathways implicated |
|---|---|---|---|---|---|---|---|---|---|
| Li et al. (Li et al., 2011) | 2011 | GC-MS (Plasma) | — | 88 type 2 diabetes of different stages of DR | — | Chinese | Not validated pyruvic acid, l-aspartic acid | Not validated arachidonic acid, trans-oleic acid, linoleic acid, Β-hydroxybutyric acid | — |
| Chen et al. (Chen et al., 2016) | 2016 | GC-MS (Plasma) | HbA1c | 40 type 2 diabetes with moderate NPDR | 40 type 2 diabetes without DR | Singaporeans of South Indian | 2-deoxyribonic acid, 3,4-dihydroxybutyric acid, erythritol, gluconic acid, ribose | Maltose | Pentose phosphate pathway |
| Rhee et al. (Rhee et al., 2018) | 2018 | GC-MS, UPLC-MS (Plasma) | Age, sex | 72 type 2 diabetes with NPDR and 52 type 2 diabetes with PDR | 74 type 2 diabetes without DR | Korean | Glutamine, glutamine/glutamic acid | Glutamic acid | — |
| Zhu et al. (Zhu et al., 2019) | 2019 | LC-MS (Plasma) | — | 21 type 2 diabetes with PDR | 21 type 2 diabetes without DR | Chinese | Not validated fumaric acid, uridine, acetic acid, cytidine | — | Alanine, aspartate and glutamate metabolism, caffeine metabolism, beta-alanine metabolism, purine metabolism, cysteine and methionine metabolism, sulfur metabolism, sphingosine metabolism, arginine and proline metabolism |
| Xuan et al. (Xuan et al., 2020) | 2020 | GC-MS, LC-MS (Serum) | Age, sex | 350 type 2 diabetes of different stages of DR | 111 type 2 diabetes without DR | Chinese | 12-HETE, 2-piperidone | — | Energy metabolism, amino acid metabolism, lipid metabolism |
| Zuo et al. (Zuo et al., 2021) | 2021 | UPLC-ESI-MS/MS (Serum) | Age, sex, BMI, HbA1c | 46 type 2 diabetes of different stages of DR | 46 type 2 diabetes without DR | Chinese | Phenylacetylglutamine, nicotinuric acid, ornithine | Linoleic acid | linoleic acid metabolism, alanine, aspartate and glutamate metabolism, phenylalanine metabolism |
Abbreviations: GC-MS, gas chromatography-mass spectrometry; UPLC-MS, ultra-performance liquid chromatography-mass spectrometry; LC-MS, liquid chromatography-mass spectrometry; UPLC-ESI-MS/MS, ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry; HbA1c: glycated hemoglobin; BMI, body mass index; DR, type 2 diabetes mellitus with diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy.