Decreased peripheral blood mitochondrial DNA content is related to HbA1c, fasting plasma glucose level and age of onset in Type 2 diabetes mellitus

Diabet. Med. 29, e47e54 (2012) Abstract Aims Mitochondrial DNA (mtDNA) content is essential for maintaining normal mitochondrial function, and the mitochondrial function is critical for the production and the release of insulin in Type 2 diabetes mellitus. We investigated whether peripheral blood mtDNA content was reduced in Type 2 diabetes, and what were the major factors? Methods The mtDNA content of peripheral blood in a sample of 147 Type 2 diabetes and 170 normal Chinese subjects was determined by amplification of the mitochondrial gene CYT-B and normalized by a nuclear DNA beta-globin gene. Fasting plasma glucose, HbA1c, fasting plasma insulin and lipid profile (HDL-cholesterol, LDL-cholesterol, total cholesterol, triglyceride) were analysed with commercial kits on an automatic analyser. Results In Type 2 diabetes group, the mean HbA1c was 62 mmol/mol (7.8%). Moreover, BMI, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, LDL-cholesterol, triglyceride, fasting plasma insulin and homeostasis model assessment for insulin resistance were significantly higher in Type 2 diabetes group than that in control group. Peripheral blood mtDNA content was 24% lower than that in the controls (1.4 +/- 0.5 vs. 1.8 +/- 0.7, P < 0.001). The mtDNA content was negatively correlated with BMI, fasting plasma glucose, fasting plasma insulin, homeostasis model assessment for insulin resistance (P < 0.01), and age, triglyceride and LDL-cholesterol levels (P < 0.05); while positively correlated with HDL-cholesterol level (P < 0.05) in both groups. Stepwise regression analysis indicated that HbA1c, fasting plasma glucose and age of onset were the major factors affecting the mtDNA content in the Type 2 diabetes group; however, BMI was the only variable associated with lower mtDNA content in control group. Conclusion Our results demonstrate that lower peripheral blood mtDNA content is associated with Type 2 diabetes in Chinese individuals, and HbA1c, fasting plasma glucose and age of onset are the major factors affecting the mtDNA content.