Potential relationship between peripheral blood mitochondrial DNA content and insulin resistance and secretion in...

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 (1230 +/- 0.05 vs. 1513 +/- 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.