Cardiac autonomic neuropathy (CAN) in type-1 diabetes mellitus patients and its association with the duration of disease and glycemic control.

OBJECTIVE: To determine the frequency of Cardiac Autonomic Neuropathy (CAN) in type-1 Diabetes mellitus patients and its association with the duration of disease and glycemic control.

STUDY DESIGN: Descriptive study.

PLACE AND DURATION OF STUDY: Department of Medicine, Liaquat University Hospital, Hyderabad/Jamshoro, from December, 2004 to April, 2005.

METHODOLOGY: Fifty patients of type-1 Diabetes Mellitus (DM) of >or=10 years duration were selected. CAN was evaluated in terms of presence of resting tachycardia, loss of sinus arrhythmia and heart rate response to Valsalva maneuver by electrocardiogram (ECG). An R-R variation with respiration of >15 beats per minute was taken normal, while 10-15 beats and <10 beats per minute were taken as borderline and definitive CAN respectively. QTc intervals were measured. Patients with HbA1c levels<7% were considered as well-controlled. The associations between CAN, the duration of diabetes and the diabetic control were determined.

RESULTS: The mean age was 35.16+/-10.58 years with 32 males and 18 females. The mean values for the known duration of diabetes and HbA1c were 13+/-7.3 years and 9.36+/-2.5 mg/dl respectively. Definitive and borderline CAN were noted in 20% and 24% respectively. Variability of heart rate with respiration was significantly related to the duration but not to the control of the diabetes (p<0.05). QTc showed a significant correlation with the known duration of diabetes and heart rate variability with respiration (p<0.05). Most of the patients had uncontrolled glycemic status.

CONCLUSION: Cardiac autonomic neuropathy is common in long standing type-1 diabetics. CAN resulted in prolonged QTc interval that may result in cardiac arrhythmias and even death. Intensive glycemic control improves the cardiac autonomic nerve functions.