Type 1 diabetes risk and autoantibody positivity in Sardinian migrants in the province of Pavia

BACKGROUND: Type 1 diabetes is an autoimmune disease. Genetics as well as environmental factors seem to play a role in the pathogenesis of type 1 diabetes. AIMS: We sought to investigate the possible relationship between migration from Sardinia to a low incidence area of type 1 diabetes (Lombardy) and the prevalence of autoantibody positivity. METHODS: We enrolled 554 Sardinian immigrants and 226 of their offspring. All subjects underwent a complete anamnestic evaluation. Fasting blood glucose, HbA1c, GADA and IA-2 were measured in all study participants. Additionally, the presence of risk haplotypes (HLA-DR3 –DR4 and DQB1/0302) was determined. After a seven-year follow-up, high genetic risk and/or autoantibody positivity subjects were re-evaluated. RESULTS: Among Sardinian immigrants, the prevalence of type 1 diabetes was 0.9%, while in the offspring group, the prevalence was 0.4%. After removing type 1 diabetic patients, the GADA prevalence was 2.4% in the immigrant group and 3.8% among their offspring. Among Sardinian immigrants, the IA-2 prevalence was 0.7%, while all offspring were IA-2 negative. After a seven-year follow-up, 85.7% of GADA-positive migrants had persistent GADA positivity. Two GADA-negative offspring subjects turned positive. None of the study participants developed diabetes during the follow-up. CONCLUSIONS: The present study showed a higher prevalence of GADA positivity within Sardinian immigrants at high genetic risk; GADA positivity may represent the first detectable phase of type 1 diabetes. After a seven-year follow-up, none of the high genetic/antibody risk group subjects developed type 1 diabetes. However, it seems reasonable to strictly control high-risk individuals in order to diagnose subclinical diabetes.