Cardiac Autonomic Neuropathy — CAN — is damage to the nerves that regulate heart rate and blood vessel tone. It's one of the most common complications of long-standing diabetes, and one of the least screened for. Unlike peripheral neuropathy, which shows up as numbness or tingling a patient can report, CAN develops quietly: heart rate stops responding normally to breathing, standing, or exertion, and by the time symptoms appear — dizziness on standing, exercise intolerance, a resting heart rate that won't budge — the underlying nerve damage is often already advanced.
Why it's so often missed
A standard cardiac work-up — ECG, echo, lipid profile — doesn't test autonomic reflexes at all. CAN doesn't show up on any of them. The condition is only detectable through tests that specifically challenge the autonomic nervous system: deep breathing, a change in posture, a controlled expiratory effort. Without a dedicated reflex-testing protocol, CAN can progress for years before it's caught, usually only after a patient reports symptoms severe enough to raise suspicion.
How CAN is actually diagnosed
The clinical reference standard is Ewing's battery — a set of five standardised cardiovascular reflex tests, developed to give autonomic function a repeatable, quantifiable measurement rather than a subjective impression. NIBRA-CS® runs this as its Full Test Battery: resting recording, deep breathing, response to standing, the Valsalva manoeuvre, a five-minute HRV recording, postural hypotension, and sustained handgrip — seven elements in one fixed, automatically guided sequence.
Why staging matters, not just detection
A binary "has CAN / doesn't have CAN" result isn't especially useful on its own — what changes clinical management is knowing where a patient sits on that progression. Early-stage CAN is a reason to tighten glycaemic control and monitor more closely. Definite or Severe CAN changes how a patient is risk-stratified for cardiovascular events and, notably, for anaesthesia and surgery — CAN is an established predictor of perioperative cardiovascular instability, which makes preoperative screening one of its more consequential use cases.
Validated in real clinical settings
NIBRA-CS® isn't a research prototype — it's a CDSCO-licensed medical device with a commercial unit deployed at RIMS Ranchi, where PHC-level screening integration is currently underway, and clinical validation and pilot studies conducted at institutions including AIIMS Kalyani, JIMS Budge Budge, and IIMC Sonarpur, extending the validation dataset across diverse patient populations.
See the full test battery and how CAN staging is reported