A 
continuous glucose monitoring system may include a hand-held monitor, a 
transmitter, an 
insulin pump, and an orthogonally redundant glucose sensor, which may comprise an optical glucose sensor and a non-optical glucose sensor. The former may be a 
fiber optical sensor, including a competitive 
glucose binding affinity 
assay with a glucose analog and a 
fluorophore-labeled glucose 
receptor, which is interrogated by an optical interrogating 
system, e.g., a stacked planar integrated optical 
system. The non-optical sensor may be an electrochemical sensor having a plurality of electrodes distributed along the length thereof. Proximal portions of the optical and electrochemical sensors may be housed inside the 
transmitter and operationally coupled with 
instrumentation for, e.g., receiving signals from the sensors, converting to respective glucose values, and communicating the glucose values. The sensors' distal portions may be inserted into a user's body via a single delivery needle and may be co-located inside the user's body.