Geographic location determines beta-cell autoimmunity among adult Ghanaians: Findings from the RODAM study.

Christiane S Hampe,Diomira Sahabandu,Tanja Telieps,Matthias B Schulze,Ina Danquah,Frank P Mockenhaupt,Liam Smeeth,Olov Rolandsson,Joachim Spranger,Charles Agyemang,Vivien Kaiser

doi:10.1002/iid3.306

Abstract

IntroductionBeta‐cell autoantibodies are established markers of autoimmunity, which we compared between Ghanaian adults with or without diabetes, living in rural and urban Ghana and in three European cities.MethodsIn the multicenter cross‐sectional Research on Obesity and Diabetes among African Migrants (RODAM) study (N = 5898), we quantified autoantibodies against glutamic acid decarboxylase (GAD65Ab) by radioligand binding assay (RBA) and established cut‐offs for positivity by displacement analysis. In a subsample, we performed RBA for zinc transporter‐8 autoantibodies (ZnT8Ab). Associations of environmental, sociodemographic, and clinical factors with GAD65Ab were calculated.ResultsIn this study population (age: 46.1 ± 11.9 years; female: 62%; Ghana‐rural: 1111; Ghana‐urban: 1455; Europe: 3332), 9.2% had diabetes with adult‐onset. GAD65Ab concentrations were the highest in Ghana‐rural (32.4; 10.8‐71.3 U/mL), followed by Ghana‐urban (26.0; 12.3‐49.1 U/mL) and Europe (11.9; 3.0‐22.8 U/mL) with no differences between European cities. These distributions were similar for ZnT8Ab. Current fever, history of fever, and higher concentrations of liver enzymes marginally explained site‐specific GAD65Ab concentrations. GAD65Ab positivity was as frequent in diabetes as in nondiabetes (5.4% vs 6.1%; P = .25). This was also true for ZnT8Ab positivity.ConclusionGeographic location determines the occurrence of GAD65Ab and ZnT8Ab more than the diabetes status. Beta‐cell autoimmunity may not be feasible to differentiate diabetes subgroups in this population.

Highlights

Beta‐cell autoantibodies are established markers of autoimmunity, which we compared between Ghanaian adults with or without diabetes, living in rural and urban Ghana and in three European cities
The present study aimed at determining the potential of beta‐cell autoantibodies to classify diabetes and to guide its therapy among 5898 Ghanaian adults
Using a highly specific detection method for GAD65Ab, surprisingly, we observed a similar prevalence of GAD65Ab positivity between individuals with and without adult‐onset diabetes

Summary

Introduction

Beta‐cell autoantibodies are established markers of autoimmunity, which we compared between Ghanaian adults with or without diabetes, living in rural and urban Ghana and in three European cities. According to the World Health Organization (WHO), the number of adults with diabetes has doubled to 422 million between 1980 and 2014.1 While this rapid increase has largely been attributed to the emergence of type 2 diabetes in low‐ and middle‐income countries, the distinction between the major diabetes subtypes is not trivial This might be true for Africans in their country of origin and for African migrants in Europe; both groups are disproportionately affected by diabetes.[2] Conventionally, the disease etiology determines diabetes subclassification and disease management.[3] Type 1 diabetes is characterized by beta‐cell destruction and autoimmunity, and type 2 diabetes results from insulin resistance and/or insulin secretory defects.[3] there is an overlap between these subtypes. GAD65Ab are established sensitive and specific biomarkers of autoimmunity for newly diagnosed type 1 diabetes (T1D) at a young age and for adult‐onset autoimmune diabetes,[6,7,8] including LADA

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