Posted on behalf of Kate Larkin

Researchers have found a new blood biomarker to monitor type two diabetes. The study published in Circulation Research, is the first to show that plasma microRNAs, small RNA molecules that recognize and regulate mRNA target genes, are key indicators for monitoring the early onset of the disease.

MicroRNAs, which circulate in blood plasma vesicles, have already been proposed as potential biomarkers for other diseases including cancer and heart failure. But this research is the first to link microRNAs to type two diabetes, which is currently diagnosed by monitoring glucose levels.

“Complications of diabetes starts in the blood vessels so standard glucose tolerance tests are not assessing the vascular risk. Our research is a new tool for monitoring and even predicting type two diabetes using RNAs as a diagnostic tool,” says Manuel Mayr, head of proteomics at King’s College London who led the plasma microRNA study and presented the results today at the British Science Festival in Birmingham.

In the largest population-based study of its kind, microRNAs were measured in over 800 participants, some with type two diabetes and others as controls, at five year intervals from 1990 to 2005. The work formed part of the Bruneck study, a cardiovascular and human disease survey of heart and other diseases set up in 1990 in northeastern Italy, led by Stefan Kiechl from the King’s College London British Heart Foundation Centre. Taking blood plasma samples and using real-time PCR (polymerase chain reaction) and microarray screening, the researchers identified 700 microRNAs.

But to tease apart the function of the microRNAs and their role in type two diabetes, the researchers had to take another step. “MicroRNAs are all interconnected, you can’t just pick one. Our work is novel because it puts micro-RNA work into a network context,” says Mayr. The researchers used a technique called micro-RNA relevance network inference to work out the complex regulatory networks of the micro-RNAs. And when they did this, they noticed something interesting.

“The levels of five microRNAs were seen to change before the onset of type two diabetes. In particular we found that a decrease of microRNA-126 was consistently associated with prevalence and incidence of the disease,” says Mayr. MicroRNA-126 is highly enriched in normal endothelial cells and is vital for the vessel health including wound repair. But under stress, the cell releases less of the micoRNA causing the health of the blood vessel to deteriorate. “Our study provides the first evidence that plasma microRNAs, including endothelial microRNA-126, are deregulated in patients with type two diabetes,” says Mayr.