Background  To investigate the genetic features of fulminant type 1 diabetes mellitus in the northern populations of China.

Methods Analyzed the clinical features of two cases of fulminant type 1 diabetes from the Second hospital of Dalian Medical University underwent gene polymorphism detection. Used ‘direct sequencingr’ method to locate and observe following polymorphism: rs1800610 in TNF gene.

Results The SNP of locus in both patients were G/G genotype and a heterozygous mutation c.186+364A＞G in its intron region was observed in both patients.

Conclusion The genotype G/G at locus rs1800610 may be a susceptibility genotype for fulminant type 1 diabetes, a heterozygous mutation c.186+364A＞G in its intron region may be have a direct correlation with the pathogenesis of fulminant type 1 diabetes.