Diagnostic value of anthropometric and biochemical markers of adiposopathy in latent autoimmune diabetes in youth

Background. Accurately differentiating slowly progressive autoimmune diabetes phenotypes, particularly latent autoimmune diabetes in youth (LADY), from classical type 1 (cT1DM) and type 2 diabetes (T2DM) remains a major diagnostic challenge in clinical endocrinology. The purpose of the study was to evaluate the functional state of pancreatic β-cells, liver enzyme profiles, and robust surrogate markers of adiposopathy (lipid accumulation product, LAP; visceral adiposity index, VAI; waist-to-height ratio, WHtR) in patients with LADY compared to latent autoimmune diabetes in adults (LADA), cT1DM, and T2DM. Materials and methods. A cross-sectional comparative study included 141 patients divided into four groups: LADA (n = 36), LADY (n = 30), cT1DM (n = 40), and T2DM (n = 35). Fasting C-peptide, basal insulin, liver enzymes (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase), and adiposopathy indices (LAP, VAI, WtHR) were evaluated. Results. Fasting C-peptide levels in LADY (0.62 ng/mL) and LADA (0.60 ng/mL) were identical (p = 0.995), being 6.2-fold higher than in cT1DM (0.10 ng/mL, p < 0.001), but 7.9 times lower than in T2DM (4.91 ng/mL, p < 0.001). Patients with LADY exhibited low visceral adiposity levels (LAP 16.82, VAI 2.11, WtHR 0.45), demonstrating a 4.0-fold reduction in LAP and a 3.0-fold reduction in VAI compared to T2DM (p < 0.001). Liver enzymes in LADY remained within normal reference ranges. Conclusions. LADY is characterized by preserved residual β-cell secretion without primary systemic adiposopathy or lipotoxicity. Integrating LAP and VAI scores alongside C-peptide evaluation significantly improves the accuracy of differential diagnosis at the primary care level. LAP and VAI can be considered as additional surrogates available in outpatient practice markers of metabolic differentiation within the spectrum of slowly progressive autoimmune forms of diabetes (LADY/LADA), complementing serological verification (GADA/IA-2/ZnT8) and C-peptide assessment, especially in situations where the latter do not provide differences between groups.