When it hurts, when I remember and of course when I read a thread mentioning changing lancets that prompt the ah I haven't changed mine....
I haven't yet heard of a case where not changing your lancet has effected the BG reading, but there again has anybody thought of studing this?
But I can see the theory behind what you're saying, if a contaimate laying on the skin is enough to produce a false reading, the same could be said about a contaimate on the lancet itself...
If this was happening, then previous reading would also be a high reading! As the blood that's contaminating the lancet would also have to be high around the same mark!
There is two theorie here that might give a glue...
One being that your quick acting insulin is lasting longer in your system than you thing, it's highest peak is around the 2 hour mark, then reduces and then in theory it tails off and out of the sytem by 4 hours, but for some the tail off is a lot longer and they can have quick acting insulin still working after 6 hours...
Or
That you have your long acting insulin wrongly adjusted so that by the time you had dinner, the long acting insulin had dealt with the liver with enough left over to help deal with the carbs from the pie and previous meal ect...
Mind you I know they say change lancet with every test, but with saying all that I haven't actually heard of anyone getting a infection from reusing a lancet! I've been testing my bloods now for 20 years and so has my husband and as yet neither of us has every had a infection due to testing!!!!