Comparison of cardiac autonomic function across complete glycaemic spectrum

Area of Science:

• Cardiology
• Endocrinology
• Autonomic Nervous System Research

Background:

• Autonomic imbalance is a key mechanism in metabolic dysregulation in diabetes mellitus.
• Previous reports on autonomic function in first-degree relatives of diabetes (FDRD) and prediabetes are controversial.
• Assessing autonomic function across the glycemic spectrum is crucial for understanding diabetes pathophysiology.

Purpose of the Study:

• To assess and compare autonomic function across the complete glycemic spectrum in an Indian population.
• To investigate autonomic dysfunction in normoglycemic individuals, FDRD, prediabetes, and diabetes.
• To clarify controversial findings regarding autonomic function in FDRD and prediabetes.

Main Methods:

• Short-term heart rate variability (HRV) analysis.
• Cardiac autonomic reactivity tests including orthostatic tolerance and deep breathing exercises.
• Assessment of blood pressure and heart rate responses, and diastolic response to isometric handgrip exercise.

Main Results:

• Resting heart rate and HRV parameters (Total power, LF, HF, SDNN, RMSSD, NN50, pNN50) significantly worsened across the glycemic spectrum (Control < FDRD < Prediabetes = Diabetes).
• Cardiac autonomic reactivity (30:15 ratio, E:I ratio) decreased in prediabetes and diabetes groups compared to controls and FDRD.
• Diastolic response to isometric handgrip increased along the glycemic spectrum, starting from FDRD.

Conclusions:

• Autonomic dysfunction is evident even in first-degree relatives of individuals with diabetes.
• Autonomic dysfunction progressively increases across the glycemic spectrum from healthy individuals to those with diabetes.
• Early detection and management of autonomic dysfunction may be important in preventing diabetes progression.