Effect of Low-intensity Aerobic Regular Activity on Heart Rate Variability in Type 1 Diabetes

The ELARA-T1D study aims to investigate the impact of regular, long-standing low-intensity aerobic physical activity on heart rate variability (HRV) and cardiovascular autonomic neuropathy (CAN) in patients with Type 1 Diabetes Mellitus (T1DM). While physical activity is a cornerstone of diabetes management, fear of hypoglycemia and lack of specific guidelines often prevent patients from engaging in exercise. The mechanisms by which physical activity improves cardiovascular outcomes are not yet fully understood. Intensity matching threshold has been linked to longevity and mitochondrial efficiency, while enhancing capillary density and mitochondrial quality. This study focuses on reducing cardiovascular risk in T1DM through an unstructured low-intensity physical activity five days per week for 30-60 min per exercise, per exercise, performed at the intensity matching aerobic threshold.

This is a randomized, parallel-assignment longitudinal study. Following a screening phase (0-4 months) to verify inclusion/exclusion criteria and baseline laboratory status, eligible participants had been randomized into two groups:

Experimental Group (Group A): Introduction of low-intensity aerobic activity five days per week for 30-60 minutes. The intensity is individually determined via cardiopulmonary exercise testing (CPET) to achieve training zone 2.

Control Group (Group B): Maintenance of low-activity lifestyle (not exceeding 30 minutes, less than five days per week).

The physical activity protocol is monitored using heart rate tracking (Garmin watches) to ensure patients stay within the prescribed intensity zones.

Assessment of glycemic control using the ambulatory glucose profile (APG) was conducted using a Guardian 4 continuous glucose monitoring (CGM) system (Medtronic, Northridge, CA, USA).

The study evaluates the progression of Cardiovascular Autonomic Neuropathy (CAN) using the 24-hour Holter ECG monitoring to assess HRV

The assessment schedule is as follows:

Baseline (Month 0): Laboratory testing (CBC, UACR, HbA1c, BUN, eGFR, AST, ALT, CK, lipid profile), evaluation of microvascular complications, Cardiac ultrasound, HRV assessment ( 24h Holter), cardiopulmonary exercise testing (CPET), evaluation of glycemic control using the ambulatory glucose profile (APG).

Follow-up (Months 6): Repeat laboratory testing, cardiopulmonary exercise testing (CPET) and APG to track changes in cardiovascular fitness and metabolic control.

Final visit (Months 12): Repeat laboratory testing, evaluation of microvascular complications, HRV assessment and APG to track changes in cardiac autonomic function and metabolic control.

In addition, all subjects underwent CT coronary angiography. Long-term follow-up: Continuous monitoring every 6 months up to 60 months to evaluate the long-term sustainability of the intervention's effects on cardiovascular health and chronic vascular complications Objectives The primary goal is to determine if consistent, low-intensity exercise can delay the onset of CAN or to prevent progression of incipient CAN and improve cardiovascular fitness.

Inclusion criteria

• Diagnosis of Type 1Diabetes at least six months prior to study enrollment
• Male or female patients over 18 years
• Willingness to perform physical activity 5 days/week.
• Absence of heavy, chronic microvascular complications.
• Absence of established Cardiovascular neuropathy.
• Absence of established ASCVD.

Exclusion criteria

• Type 2 Diabetes
• Active engagement in professional sports
• Limb amputation
• Blindness
• Active malignancy