Significance of combined screening for GADA, ICA, and IAA in new-onset type 2 diabetes mellitus in adults for early diagnosis of latent autoimmune diabetes.

Abstract

Purpose: To investigate the detection rate of latent autoimmune diabetes in adults (LADA) among newly diagnosed type 2 diabetes mellitus (T2DM) patients and analyze their clinical characteristics, with the aim of guiding treatment and improving prognosis.

Methods: Glutamic acid decarboxylase autoantibody (GADA), islet cell autoantibody (ICA), insulin autoantibody (IAA), blood pressure, height, weight, and BMI, as well as lipid profiles, fasting plasma glucose, insulin, C-peptide, HbA_1c, thyroid-stimulating hormone (TSH), thyroglobulin antibody (TGAb), and thyroid peroxidase antibody (TPOAb) levels were measured in 352 newly diagnosed T2DM patients with disease duration of less than 1 year and non-ketotic onset. The incidence of LADA was calculated, and clinical characteristics of these patients were compared with those of T2DM patients without autoantibodies.

Results: The detection rate of LADA was 7.10%. Among the 25 LADA patients, 22 had GADA, 5 had ICA, 2 had IAA, and 2 were positive for all three antibodies. The percentages of GADA, ICA, and IAA among LADA patients were 88.00%, 20.00%, and 8.00%, respectively. Compared with the autoantibody-negative group, LADA patients had lower BMIs and total cholesterol, lower insulin and C-peptide levels, higher neutrophil counts, and increased abnormal TSH levels and TPOAb positivity (P < 0.05). LADA patients exhibited reduced CD4⁺ T cell expression levels, which were lower than those in patients without autoantibodies, while LADA patients' CD8⁺ T cell levels were within the normal range and slightly higher than those in patients without autoantibodies, reflecting a lower CD4⁺/CD8⁺ ratio in LADA patients.

Conclusion: A proportion of newly diagnosed T2DM patients have LADA. Early screening for GADA, ICA, and IAA should be performed in newly diagnosed T2DM patients with low BMI and poor islet function. LADA patients may have higher expression of inflammatory immune factors, lower total cholesterol, and a lower CD4⁺/CD8⁺ ratio. The decline in [Formula: see text]-cell function in LADA patients may be associated with decreased CD4⁺ T cell expression.