ABSTRACT
Both qualitative and quantitative changes in mitochondrial DNA [mtDNA] have been implicated in the pathogenesis of diabetes mellitus. In this study, we investigate whether peripheral blood mtDNA [pb-mtDNA] is decreased and if there is any relation between its content and the parameters of both insulin resistance and secretion in offspring of diabetic subjects. The pb-mtDNA content was measured by real time polymerase chain reaction with mitochondrial- specific fluorescent probe, normalized by a nuclear DNA, 28S rRNA gene, in 42 offspring of type 2 diabetic patients and 12 age-, sex- and body mass index [BMI]- matched normal subjects. The correlations between pb-mtDNA content and the parameters of insulin resistance and secretion were studied. Our results indicated that the level of pb-mtDNA was lower in offspring of diabetic subjects than in control subjects [1.230 +/- 0.05 vs. 1.513 +/- 0.02 in the offspring and control subjects, respectively, P <0.05]. Also, pb-mtDNA content was significantly correlated with logarithmically transformed insulin sensitivity index [r = 0.5, P<0.05], fasting C-peptide [r = -0.8, P<0.05], acute insulin response [r = -0.8, P<0.05] and late insulin response [r = -0.7, P <0.05] in offspring of diabetic subjects. In conclusion, quantitative mtDNA status might be a hereditary factor associated with type 2 diabetes and is correlated negatively with indexes of insulin resistance and insulin secretion in offspring of diabetic patients. So, pb-mtDNA content could serve as an indicator of insulin sensitivity and insulin secretion in those subjects