Immunological and clinical characteristics of latent autoimmune diabetes in the elderly

Latent autoimmune diabetes in adults (LADA) is determined by both a noninsulin-dependent clinical presentation and an autoimmune pathogenic process. Glutamic acid decarboxylase antibody (GADA) constitutes the most important marker, although IA-2A and ZnT8A also define LADA presentation. Type 2 diabetes mellitus (T2DM) is the most prevalent type particularly over 65 years old. Studies about autoimmunity in this age group are scarce.

The aim of this work was to determine whether three autoantibodies for diabetes autoimmunity were present in elderly T2DM patients, and to assess the distinctive clinical features of autoantibody-positive patients.

We recruited 153 patients with diabetes with onset of diabetes after 65 years of age and a BMI under 30 kg/m² .

The prevalence of at least one of the autoantibodies was 15.68% (24/153). The most prevalent autoantibody was GADA with 8.49% (13/153), followed by ZnT8A with 6.50% (10/153) and IA2A with 1.96% (3/153). The autoimmunity-positive group presented higher HbA1c (7.01 ± 1.98 vs 6.35 ± 1.01; P = 0.007) and more prevalent insulin therapy (25% vs 10.85%; P = 0.047). GADA-positive patients with diabetes presented higher FPG (7.79 ± 3.79 mmol/L vs 6.43 ± 1.6 mmol/L; P = 0.014) and insulin therapy more frequently (46% vs 10.71%; p = 0.015). GADA titre levels in the individuals with BMI under 27 kg/m² were higher (35.00 ± 4.20) than those in the group with BMI over 27 kg/m² (8.83 ± 3.041; P = 0.0005).

Autoantibodies GADA and Znt8A may be useful markers in identifying a subgroup of older patients with a clinical presentation of diabetes which could be characterized as latent autoimmune diabetes in the elderly.