Consequences of the compromised vascular system in diabetes mellitus (DM) are among the most devastating complications. Reduction in blood flow and oxygen uptake of skeletal muscle leads to muscle fatigue and impaired skeletal muscle post-exercise adaptation. Recent studies showed that intermittent vacuum therapy (IVT) augments the blood flow of the foot in people with DM. This pilot study investigates the effects of combined IVT and aerobic exercise in improving lower limb muscle oxygenation and distal circulation in individuals with DM. Positive results of the study shed light on strategy that enhances the effectiveness of aerobic exercise in people with DM.

This study addresses the significant global health issue of Diabetes Mellitus (DM), a chronic condition characterized by the body's inability to properly use and store glucose. With an estimated 422 million adults affected worldwide in 2014, projected to increase to 629 million by 2045, DM poses a substantial public health challenge. Specifically, in Hong Kong, the prevalence was around 8.4% in 2014, and by 2021, DM had become the tenth leading cause of death. One of the most devastating complications of DM is the damage to the vascular system.

Recent developments in treatment options include Intermittent Vacuum Therapy (IVT), a technique initially developed for astronauts to mitigate orthostatic complications. IVT involves the application of alternating negative and ambient pressures to the lower extremities, which has been shown to enhance blood flow by promoting rhythmic vasodilation and compression. This method has successfully increased foot perfusion in both healthy volunteers and patients with Peripheral Artery Disease (PAD), highlighting its potential benefits in improving circulation without direct contact with the patient's limb, thereby minimizing the risk of cross-infection.

The study also explores the role of aerobic exercise in improving insulin sensitivity, blood sugar control, and reducing DM-related complications. However, DM patients often face challenges such as muscle fatigue during exercise due to impaired glucose uptake, mitochondrial dysfunction, microvascular damage, and atherosclerosis, which limit blood supply to skeletal muscles, affecting exercise capacity.

Given the positive effects of IVT on distal circulation in PAD patients but its unexplored benefits in DM patients when combined with aerobic exercise, the study hypothesizes that IVT could enhance distal circulation, oxygen uptake, and nutrient delivery to the skeletal muscle of the lower limbs. This could, in turn, amplify the benefits of aerobic training on skeletal muscle in DM patients.

The study's objectives are twofold:

To evaluate the feasibility, safety, and patient acceptance of combining IVT with an exercise program in DM rehabilitation.

To examine the effectiveness of this combined approach on lower-limb perfusion, muscle physiology, and locomotion functions in DM patients.

Inclusion Criteria:

• age between 55 and 80 years old,
• being diagnosed with Type 2 DM,
• being able to give informed consent to participate in the study.
• able to walk without assistance

Exclusion Criteria:

• have a conditions that contraindications to IVT: pregnancy, abdominal wall hernia, recent (<8 weeks) trauma of the lower limbs,
• have an open wound on the lower extremity or with lower extremity infection,
• have any orthopaedic or medical conditions that could hinder the assessment and training.

Individual participant data will not be shared to other researchers