Assessing the Impact of BMI and Glycaemic 
Control on Cardiac Autonomic Neuropathy in 
Patients with Early and Long-standing Diabetes 
Mellitus: A Window of Opportunity.

Background: Cardiac autonomic neuropathy (CAN) is a well-known, yet underreported, complication of Diabetes mellitus (DM). CAN assessment can be performed using heart rate variability (HRV) and Ewing's battery of tests. Severity of CAN may be affected by multiple factors like glycaemic control, obesity and co-existing distal neuropathy. However, the relationship between CAN and these factors remains underexplored. Purpose: We conducted the present study to assess the relationship between the prevalence of CAN in patients with DM and associated factors like obesity and glycaemic control. Methods: Clinically diagnosed patients of DM were recruited. They were divided into duration <5 years (early onset, 'Dur < 5') and ≥5 years (long-standing, 'Dur ≥ 5') and evaluated using HRV and Ewing's battery of tests. Apparently, healthy young adult controls were recruited as controls. Cardiac autonomic tone and reactivity parameters were compared between the groups. Results: We recruited 50 patients with DM (25 'Dur < 5' and 25 'Dur ≥ 5') and 34 healthy controls. Controls were significantly younger than the patients. Height, weight and BMI were comparable between the groups. Patients had impaired cardiac autonomic tone but preserved response to reactivity tests when compared with controls. Normal BMI and good glycaemic control, indicated by lower values of HbA1C, may be responsible for these results. Conclusions: Patients with DM demonstrated reduced tone but preserved autonomic reactivity, even when compared with younger, apparently healthy controls. Normal BMI and relatively lower HbA1C values may contribute to this phenomenon. Such patients may be identified and targeted for early clinical intervention for ANS salvage.