1Jehan A. M. El-Sharnooby and 2Laila M. Sayed Ahmed
Departments of 1Clinical
Pathology and 2Internal Medicine,
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.