– Dr. Debasish Maji
Diabetes is characterized by long term microvascular complications which include mainly-Retinopathy, Nephropathy and Neuropathy. It has been observed that these complications are more commonly seen in patients with uncontrolled diabetes and with long duration of diabetes. It is always necessary to look for other microvascular complications if any one type is found in a patient. Diabetic neuropathy is a common microvascular complication and affects both somatic nerves and autonomic nerves. Examination of somatic nerves, specially peripheral nerves is a very common and mandatory clinical examination procedure,in a case of diabetes which further can be authenticated by electrophysiological studies. Interestingly examination of autonomic nervous system is not followed routinely in day to day examination of diabetic patients, though it is known that autonomic nerves innervetes every organ in the body and if affected may manifest as a diverge range of symptoms including tachycardia, orthostatic hypotension, exercise intolerance (cardiac autonomic neuropathy); nausea, vomiting, constipation, diarrhea (gastrointestinal), urinary retention and or incontinence, sexual dysfunction including erectile dysfunction (genitourinary), increased glycemic variability, visual disturbance and hypoglycemia unawareness. All these conditions have adverse effects on morbidity and mortality in diabetes[1]. Autonomic neuropathy affecting the cardiovascular system is termed as Cardiac Autonomic Neuropathy (CAN). Due to the involvement of vagus nerve, the vagal tone on heart rate is lost and there is sinus tachycardia; for the same reason there is impaired baroreflex sensing, leading to impaired exercise tolerance and orthostatic hypotension in diabetic patients. There are very simple non invasive objective tests to asses CAN where you need only an ECG machine. The tests include R R interval in ECG in response to deep breathing, Valsalva maneuver and postural change to assess parasympathetic system and while blood pressure changes from lying to standing position and Valsalva test assess sympathies function. These tests are simple and accurate and can be done at the clinic itself[2]. Banerjee et al has performed these tests for assessment of CAN in 236 patients and analyzed their reports in this issue, Lipid abnormalities, age and duration of diabetes were found to be more associated with CAN. Parasympathetic components are affected early; long vagus nerve could be one of the factors. Valsalva maneuvre should be avoided in those who has proliferative diabetic retinopathy. Patients with diabetes and confirmed CAN should undergo cardiac evaluation prior to surgery and prior to undertaking any exercise regimen. Diabetics should get frequent monitoring of blood glucose as they may have hypoglycemia unawareness and avoid orthostatic hypotension by proper hydration, avoidance of sudden changes of posture, using lower limb stocking.Routine tests to detect CAN should be included in the clinical work up of a diabetic patient.
References
1. Vinik AI, Maser RE, Mitchell BD, Freeman R: Diabetic autonomic neuropathy. Diabetic Care 2003:2695):1553- 1579.
2. Pop-Busui R: Cardiac autonomic neuropathy in diabetes:a clinical perspective. Diabetes Care 2010:33 (20:434-441).
