Correlating the global increase in type 1 diabetes incidence across age groups with national economic prosperity: A systematic review

BACKGROUND The global epidemiology of type 1 diabetes(T1D)is not yet well known,as no precise data are available from many countries.T1D is,however,characterized by an important variation in incidences among countries and a dramatic increase of these incidences during the last decades,predominantly in younger children.In the United States and Europe,the increase has been associated with the gross domestic product(GDP)per capita.In our previous systematic review,geographical variation of incidence was correlated with socio-economic factors.AIM To investigate variation in the incidence of T1D in age categories and search to what extent these variations correlated with the GDP per capita.METHODS A systematic review was performed to retrieve information about the global incidence of T1D among those younger than 14 years of age.The study was carried out according to the PRISMA recommendations.For the analysis,the incidence was organized in the periods:1975-1999 and 2000-2017.We searched the incidence of T1D in the age-groups 0-4,5-9 and 10-14.We compared the incidences in countries for which information was available for the two periods.We obtained the GDP from the World Bank.We analysed the relationship between the incidence of T1D with the GDP in countries reporting data at the national level.RESULTS We retrieved information for 84 out of 194 countries around the world.We found a wide geographic variation in the incidence of T1D and a worldwide increase during the two periods.The largest contribution to this increase was observed in the youngest group of children with T1D,with a relative increase of almost double when comparing the two periods(P value=2.5×e-5).Twenty-six countries had information on the incidence of T1D at the national level for the two periods.There was a positive correlation between GDP and the incidence of T1D in both periods(Spearman correlation=0.52 from 1975-1999 and Spearman correlation=0.53 from 2000-2017).CONCLUSION The incidence increase was higher in the youngest group(0-4 years of age),and the highest incidences of T1D were found in wealthier countries.

Type 1 diabetes loci display a variety of native American and African ancestries in diseased individuals from Northwest Colombia

BACKGROUND Type 1 diabetes(T1D)is a complex disease with a higher incidence in Europeans than other populations.The Colombians Living in Medellin(CLM)is admixed with ancestry contributions from Europeans,Native Americans(NAT)and Africans(AFR).AIM Our aim was to analyze the genetic admixture component at candidate T1D loci in Colombian individuals with the disease.METHODS Seventy-four ancestry informative markers(AIMs),which tagged 41 T1D candidate loci/genes,were tested by studying a cohort of 200 Northwest Colombia diseased individuals.T1D status was classified by testing for glutamic acid decarboxylase(GAD-65 kDa)and protein tyrosine-like antigen-2 autoantibodies in serum samples.Candidate loci/genes included HLA,INS,PTPN22,CTLA4,IL2RA,SUMO4,CLEC16A,IFIH1,EFR3B,IL7R,NRP1 and RNASEH1,amongst others.The 1,000 genome database was used to analyze data from 94 individuals corresponding to the reference CLM.As the data did not comply with a normal distribution,medians were compared between groups using the Mann-Whitney U-test.RESULTS Both T1D patients and individuals from CLM displayed mainly European ancestry(61.58 vs 62.06)followed by Native American(27.34 vs 27.46)and to a lesser extent the AFR ancestry(10.28 vs 10.65)components.However,compared to CLM,ancestry of T1D patients displayed a decrease of NAT ancestry at gene EFR3B(24.30 vs 37.10)and an increase at genes IFIH1(32.07 vs 14.99)and IL7R(52.18 vs 39.18).Also,for gene NRP1(36.67 vs 0.003),we observed a non-AFR contribution(attributed to NAT).Autoimmune patients(positive for any of two auto-antibodies)displayed lower NAT ancestry than idiopathic patients at the MHC region(20.36 vs 31.88).Also,late onset patients presented with greater AFR ancestry than early onset patients at gene IL7R(19.96 vs 6.17).An association analysis showed that,even after adjusting for admixture,an association exists for at least seven such AIMs,with the strongest findings on chromosomes 5 and 10(gene IL7R,P=5.56×10-6 and gene NRP1,P=8.70×10-19,respectively).CONCLUSION Although Colombian T1D patients have globally presented with higher European admixture,specific T1D loci have displayed varying levels of Native American and AFR ancestries in diseased individuals.