Background: CpG cytosine in the human insulin gene (INS) is uniquely unmethylated in pancreatic β-cells. It has been reported that a few unmethylated CpG specific PCR in circulating cell-free DNA could detect injury of pancreatic β-cells. However, the same CpG methylation pattern with these CpG sites are also existing in non-β-cells, thus the false positive results might be involved in these reports.

Aim: To develop a precise method for detecting pancreatic β-cell DNA in the circulation.

Methods: We have developed the dual Amplification Refractory Mutation System (ARMS) PCR, which amplifies only if 4 CpG sites were all unmethylated. The first ARMS PCR amplifies if 2 CpG sites (+331, 404bp of transcription start sites (TSS) of INS) are unmethylated simultaneously, and followed by the second ARMS PCR, which amplifies if 2 CpG sites (+367, 374bp of TSS of INS) are unmethylated simultaneously. This method was applied to 52 patients with type 1 diabetes (T1D) (duration 12.6 +/- 10.1 years). We confirmed the positive samples using DNA sequence analysis.

Results: Pancreatic β-cell DNA were detected in 3 T1D (11.8, 2.5, 912.7 copies in 0.1mL of serum) who are diagnosed as slowly progressive T1D, and 4 among 16 healthy control subjects (1.2, 2.2, 1.9, 3.7 copies in 0.1mL of serum).

Conclusion: We have developed the dual ARMS PCR which is a precise method to detect circulating pancreatic β-cell DNA. Almost no β-cell DNA was circulating in the long standing T1D, however, β-cell DNA was detectable in slowly progressive T1D. Also, there were not so many, but a few β-cell DNA in the circulation of healthy control subjects. Therefore, this method is useful to evaluate pathogenesis of type 1 diabetes.


A. Kuroda: None. M.Y. Yamada: None. Y. Tominaga: None. R. Suzuki: None. M. Tamaki: None. Y. Akehi: None. Y. Takashi: None. D. Koga: Employee; Self; Otsuka Pharmaceutical Co.,Ltd.. E. Shimokita: None. F. Tanihara: None. K. Kurahashi: None. S. Yoshida: None. I. Endo: None. K. Aihara: None. M. Abe: None. K. Ferreri: None. M. Matsuhisa: None.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at