Background: Lipocalin-2 (LCN2) level in type 2 diabetes mellitus (T2DM) subgroups has not been investigated. The aim of this study was to investigate LCN2 levels, insulin resistance, urinary albumin excretion, and inflammation status in T2DM subgroups.
Methods: A total of 251 patients with newly diagnosed T2DM were evaluated. LCN2, glycated hemoglobin (HbA1c), FPG, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP) levels were measured. Patients with diabetes were categorized into three subgroups: patients diagnosed with fasting plasma glucose (FPG) alone (FPG-DM), those with isolated hemoglobin A1c (HbA1c) diabetes (A1c-DM), and those who met the criteria for both FPG and HbA1c (FPG/A1c-DM). The albumin-to-creatinine ratio (ACR), estimated glomerular filtration rate (eGFR), homeostasis model assessment of insulin resistance (HOMA-IR), and adjusted LCN2 values, such as the LCN2/inflammation index (LCN2/Inf) and LCN2/creatinine (LCN2/ Cr), were calculated.
Results: The ACR, HOMA-IR, and glycosuria prevalence were significantly higher in FPG-DM than in A1c-DM. In contrast, no significant difference was observed in LCN2, eGFR, and proinflammatory cytokine levels between the two groups. Patients with FPG/A1c-DM had significantly higher LCN2, TNF-α, IL-6, and hsCRP levels than those with A1c-DM or FPG-DM. The percent difference between LCN2 and LCN2/Inf was 3.2-fold greater than that between LCN2 and LCN2/Cr in FPG/A1c-DM. The presence of FPG-DM led to a 1.8-fold increase in the prevalence of proteinuria (odds ratio, 1.876; 95% CI, 1.014 - 3.295; p < 0.001). The ability of FPG to identify proteinuria outperformed that of HbA1c (area under the curve: 0.629, 95% CI, 0.553 - 0.706 versus 0.522, 95% CI, 0.436 - 0.605, p < 0.001).
Conclusions: LCN2 elevation may be more largely due to inflammation than kidney function, particularly in FPG/A1c-DM. Patients with FPG-DM may be at a greater risk of diabetic nephropathy and insulin resistance than those with A1c-DM.