system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why home blood tests do not exist, while we can measure our sugar levels with personal devices at home?

I feel like going to get basic blood test done is a chore. Why it can't be done at home? I have the glucometer at home and its great. Is the same thing possible for a more general purpose? Education-wise I am far from anything to do with medicine, but technologically speaking, is it really a stretch?

Having a nurse come over is not what I mean by at-home testing, btw.

English is not my mother tongue, sorry if my question is not clear.

Edit: Yes, I missed most of what's going on with Theranos. It's not widely covered where I live, I will definitely watch the documentary or listen to the podcast. sounds interesting!   
Also, thank you all for your comments, so much I didn't know!
gpt
Most tests don't use blood per se, they use serum or plasma. Hard to get at those at home.

A blood count requires machines able to see, differentiate and count a variety of different cells in your blood. It is not comparable to a glucose test.