Abstract

BACKGROUND
Mitochondrial mutations and deletions, have been implicated in the pathogenesis of diabetes mellitus. This can explain only a very small proportion of the patients with diabetes mellitus. Mitochondrial DNA(mtDNA) is vulnerable to oxidative stress, resulting in both qualitative and quantitative changes. We reported that the amount of mtBNA decreased in the peripheral blood leukocyte of patients with NIDDM. In this study, we examined that decreased mtDNA content preceded the development of NIDDM{Non-insulin dependent diabetes mellitus) and correlated with various insulin resistance parameters.In this study, we demonstrated that the amount of mtDNA decreased in peripheral blood leukocyte of patients with NIDDM. Furthermore, we found that lower mtDNA levels preceded the development of diabetes mellitus. METHODS: We utilized the stored blood samples from two community-based survey conducted in Yonchon County, Korea in 1993 and 1995. We selected 23 newly diagnosed diabetic patients and 22 age- and sex-matched control subjects. The buffy coats of peripheral blood samples were used for the competitive PCR and the products pairs were separated by gel EP. The content of mtDNA was calculated with the densitometry. RESULTS: There were no difference in the initial anthropometric parameters, blood pressure and lipid profiles between subjects who became diabetic converters and non converters. The mean quantity of mtDNA was lower in the converters, with 102.8+ 41.5 copies/pg template DNA compared to 137.8+ 67.7 copies/pg template DNA of the controls(p 0.05). The significant inverse correlations were noted between mtDNA content and WHR(r=0.31, p<0.05) in the first, and fasting glucose level(r=-0.35, p<0.05), diastolic blood pressures(r=-0.36, p<0.05), and WHR(r=-0.40, p<0.01) in the second survey. The correlations with the serum levels of total and high density cholesterol, triglyceride, insulin and proinsulin were not statistically significant. CONCLUSION: Although a relationship between diabetes and mitochondrial dysfunction has been suspected. This study showed that decreased mtDNA content in peripheral blood proceded the development of NIDDM. This is the first study to demonstrate that quantitative changes in mtDNA precede the development of NIDDM.

• Keywords: NIDDM;ukocyte;quantitative PCR;mtDNA ( mitochondrial DNA );