Reading data from a glucose meter
The native interface to most glucose meters (Abbott, Bayer, J&amp;J and Roche) is a UART output.  There is circuitry at one end of the cable that translates this to USB protocol.  It is possible to read the data with a UART by using a 2.5 mm or 3.5 mm plug to connect directly with the meter.

The J&amp;J uses a 3.5 mm plug with Tip being Tx and Ring being Rx (Tx and Rx wrt your UART, not the meter), and communicates at 9600 baud.  Except for the various J&amp;J One-Touch models, the signal levels for the other brands are typically neither regular UART (0 / 3.3) or RS232 (+-5) levels but some weird combination.  Some models also swap Tx/Rx compared to the J&amp;J.  Note: the One Touch Ultra and Ultra 2 use a different (more text based) protocol than the binary protocol used by the Ultra Mini (see CoderTao's answer for a link to the latter).