I have been using wire.h I2C scanner with the MPU6050 and also get no response.
Looking at the clock and data signal on a scope the MPU6050 does respond with an ACK but wire is not reporting it. The scanner does a 8 bit clock for all other addresses but extends this to 16 bits for the 0x68 as the hardware sees the address ACK and also gets a data ACK.
On my Raspberry pi the i2cdevice 0 scanner finds the 0x68 ok.
With I2Cdev.h on the Due it also finds the mpu6050 si It looks like a problem with the wire.h driver ?? . See forum "MPU-6050 errors reading data" on how to use the i2cdev