A method of calibrating an optical glucose sensor of an orthogonally redundant sensor device for determining the concentration of glucose in a body of a user, wherein the sensor device further includes an electrochemical glucose sensor, the method comprising: (a) receiving a first signal from the electrochemical glucose sensor and a second signal from the optical glucose sensor, wherein said second signal is obtained at a first point in time; (b) receiving a meter glucose value, said meter glucose value being indicative of the user's blood glucose level and being obtained at a second point in time; (c) pairing said meter glucose value with said second signal if said second point in time is within a specified amount of time before or after said first point in time; (d) performing a validity check on the paired meter glucose value and second signal; calculating a correlation value between said first and second signals by performing linear fitting of the second signal to the first signal, and then calculating the coefficient of determination between the second signal and the first signal; if the correlation value is less than a calculated threshold, then it is determined that the first and second signals do not correlate well with each other, said meter glucose value and second signal are saved to a buffer, and steps (e) and (f) are not performed; if the correlation value is greater than a calculated threshold, then it is determined that the first and second signals correlate well with each other: (e) if said meter glucose value is a first meter glucose value of one or more meter glucose values, then calculating a mapped value for the second signal based on the first signal; and (f) calibrating the mapped value of the second signal based on said first meter glucose value; wherein orthogonal redundancy is defined as two devices employing two different technologies to reach the same goal, where the failure modes of the two devices are completely unique and do not intersect. (a) receiving a first signal from the electrochemical glucose sensor and a second signal from the optical glucose sensor, wherein said second signal is obtained at a first point in time; (b) receiving a meter glucose value, said meter glucose value being indicative of the user's blood glucose level and being obtained at a second point in time; (c) pairing said meter glucose value with said second signal if said second point in time is within a specified amount of time before or after said first point in time; (d) performing a validity check on the paired meter glucose value and second signal; calculating a correlation value between said first and second signals by performing linear fitting of the second signal to the first signal, and then calculating the coefficient of determination between the second signal and the first signal; if the correlation value is less than a calculated threshold, then it is determined that the first and second signals do not correlate well with each other, said meter glucose value and second signal are saved to a buffer, and steps (e) and (f) are not performed; if the correlation value is greater than a calculated threshold, then it is determined that the first and second signals correlate well with each other: (e) if said meter glucose value is a first meter glucose value of one or more meter glucose values, then calculating a mapped value for the second signal based on the first signal; and (f) calibrating the mapped value of the second signal based on said first meter glucose value;