The diagnostic value of serum TTCP-1, NUCB2 and CXCL12 in early type 2 diabetic nephropathy

Background: To explore the combined diagnostic value of serum Tubulinyl-Tyr carboxypeptidase 1 (TTCP-1), Nucleobindin-2 (NUCB2), and C-X-C Motif Chemokine Ligand 12 (CXCL12) for the early diagnosis of type 2 diabetic nephropathy (T2DN). Methods: From May 2023 to May 2025, 184 patients with type 2 diabetes (T2DM) treated at this hospital comprised the T2DM group. These patients were further divided into a non-T2DN group (n=116) and a T2DN group (n=68) based on whether they developed T2DN. The control group consisted of 210 healthy people who had physicals at the same hospital during the same time period. An automated biochemical analyser was used to measure the levels of serum albumin and creatinine after fasting blood glucose (FBG), retinol binding protein (RBP), serum creatinine (Scr), uric acid (UA), blood urea nitrogen (BUN), and b2-microglobulin (b2-MG). The urine albumin-to-creatinine ratio (UACR) was calculated. The KD-EPI formula was used to estimate glomerular filtration rate (eGFR). The glycated haemoglobin level was detected using a glycated haemoglobin analyser. An automated chemiluminescent immunoassay measured fasting insulin levels, and the insulin resistance index (HOMA-IR) was calculated. The levels of TTCP-1, NUCB2, and CXCL12 were detected using enzyme-linked immunosorbent assays. Pearson correlation analysis was used to investigate the associations between TTCP-1, NUCB2, and CXCL12 levels and blood glucose and renal function indicators. Multivariate logistic regression analysis was employed to analyse the factors influencing T2DN occurrence. Receiver operating characteristic (ROC) curves were constructed to assess the diagnostic value of TTCP-1, NUCB2, and CXCL12 for T2DN. Results: Compared with those in the control group, the levels of TTCP-1 and CXCL12 in the T2DM group increased, whereas NUCB2 levels dropped, and the variations were statistically significant (P<0.05). In contrast to individuals in the non-T2DM group, those in the T2DM group had a longer duration of T2DM. The levels of FBG, HbA1c, HOMA-IR, RBP, UA, UACR, b2-MG, BUN, Scr, TTCP-1, and CXCL12 were significantly lower. In comparison, eGFR and NUCB2 levels were significantly lower (P<0.05). The levels of TTCP-1, NUCB2, and CXCL12 in the T2DM group were correlated with the duration of T2DM, FBG, HbA1c, HOMA-IR, RBP, UA, UACR, b2-MG, BUN, Scr, and eGFR (P<0.05). TTCP-1, NUCB2, and CXCL12 levels were independent influencing factors for the occurrence of T2DN (P<0.05). The area under the curve for the combined diagnosis of T2DN by TTCP-1, NUCB2, and CXCL12 was 0.954, which was greater than that for the individual diagnoses (Z(combined - TTCP-1) = 3.301; Z(combined - NUCB2) = 3.590; Z(combined - CXCL12) = 4.462; all P<0.05). Conclusion: The levels of TTCP-1 and NUCB2 were elevated in T2DN patients, whereas the level of CXCL12 was decreased. These three factors are related to renal function indicators and blood sugar indicators. The combined diagnosis of these three factors could provide a theoretical basis for early clinical diagnosis and treatment.