1. A method for use with an implantable medical device for detecting hypoglycemia within a patient in which the device is implanted, said method comprising: sensing an electrical cardiac signal; deriving values representative of a pre-symptomatic physiologic response to a hypoglycemic event from the cardiac signal by deriving temporal morphological parameters within the cardiac signal that are affected by pre-symptomatic hypoglycemia and deriving spectral parameters from the cardiac signal that are affected by pre-symptomatic hypoglycemia; and detecting hypoglycemia based on the values representative of the pre-symptomatic physiologic response.