Muscle weakness in diabetes patients affects more areas of the leg than previously thought, increasing the risk of falls.
It is well understood that diabetes causes muscle weakness but was believed to be confined just to the distal muscles, towards the end of the leg such as in the calf muscle.
However, research published in the current issue of Diabetes Care, demonstrates that diabetes patients have substantial proximal muscle weakness - muscles further up the leg that include the quadriceps.
This extended weakness has consequences for patients' ability to perform everyday tasks and exacerbates the negative effects of the diabetic condition. A greater muscle weakness is also associated with a higher susceptibility of falling, thereby increasing the risk of injury.
Researcher Professor Neil Reeves, Professor of Musculoskeletal Biomechanics at Manchester Metropolitan University, said: "This muscle weakness with diabetes has important implications, meaning that patients may find everyday tasks more difficult and struggle to meet the demands of some tasks, thereby initiating a negative cycle of reduced activity, which negatively affects their diabetic condition."
Right: images taken from a diabetes patient. Left: a control participant without diabetes. Top: mid-thigh scans. Bottom: calf scans. Darker areas on the patient's images represent an increase in intramuscular noncontractile tissue (fat and connective tissue), which is highly correlated to insulin resistance and a reduction of muscle strength
Image: Manchester Metropolitan University
Typically, it is thought that the area of muscle is proportional to the force that the muscle can produce, so in other words, larger muscles are stronger. However, researchers showed that in people with diabetes the area of muscle present is not capable of producing the force we might expect based on its size - and this is due to the 'infiltration' of fat within the muscle.
Prof Reeves added: "Therefore, people with diabetes not only have smaller muscles capable of producing lower forces, but their lower leg muscles are also infiltrated by fat, which causes a further reduction in the force that can be produced, compounding their weakness."
The healthcare scientists used a Magnetic Resonance Imaging (MRI) technique to show that people with diabetes have a higher amount of intramuscular fat in the lower leg muscles.
The study is part of a series at Manchester Met to analyse the impact of diabetes, previously demonstrating diabetes patients are more likely to suffer falls and patients expend more energy to perform everyday tasks.