I would do this measure again a few more times just to see if the 6 you measured was just a fluke. If it is repeated often I would be concerned but not necessarily alarmed because I don't have no idea about the seriousness of a brix of 6 . I know there are also sticks to measure urine sugar, they can be bought off the counter if drugstores.
I would also read here or on the new ML forum what ML have said about insulin and diabetes. I know he mentioned the link with the liver and the adrenals.
I would definitely ask ML himself and ask him what he thinks about a brix measure of six or of whatever.
You see ... we still learn things on a daily basis here.