I think the original test was based on a self applied pin prick test which from past experience is not as accurate as a blood tests taken as an Arterial sample or the most commonly used, and less painful, Venipuncture Sampling. I suspect that using the Venipuncture sampling method is what has give the test a better end result.
To be honest I am only basing my theory on my experiences of using a prick test versus a V sample when obtaining accurate blood glucose levels. So don't try to engage me any scientific arguments 'cause I not joining in on this treads play times..
Add/ I certainly hope they don't use Arterial testing as that is what I have when I have my quarterly checkup on the state of my immune system problem and that way of obtaining a sample is bloody painful.