Islet cell-associated autoantibodies in Ethiopians with diabetes mellitus

Our understanding of the role of autoimmunity in the pathogenesis of diabetes in African populations is limited. This study aims to evaluate the prevalence of 4 different islet cell-associated antibodies in Ethiopian patients with diabetes and non-diabetic controls.

A total of 187 subjects from a diabetic clinic at an Ethiopian hospital were evaluated in a cross-sectional study. Fifty-five patients had type 1 diabetes mellitus (T1DM), 86 had type 2 diabetes mellitus (T2DM) and 46 were non-diabetic controls. Islet cell-associated antibodies were measured using 4 different assays for antibodies against islet cells (ICA), glutamic acid decarboxylase (GADA), insulin (IAA) and the protein tyrosine phosphatase-like IA-2 (IA-2A).

Comparing the antibody positivity in subjects with T1DM versus T2DM, the results were as follows: 29% versus 3.5% for GADA; 21% versus 2.7% for ICA; 27% versus 16% for IAA. In the control group, the only positive result was for IAA at 2%. IA-2A was absent in all groups. The combi-assay for GADA and IA-2A detected all GADA-positive subjects. T2DM patients who were GADA positive had lower BMI, lower C-peptide levels and all of them were on insulin therapy.

Compared to Caucasians, Ethiopians with T1DM have less prevalence of islet cell-associated antibodies, but the rates are higher than in T2DM. GADA is present in Ethiopians, whereas IA-2A seems to be absent. GADA positivity in T2DM correlates with clinical features of T1DM, indicating the existence in Ethiopia of the subgroup, latent autoimmune diabetes in adults.