Aging brings rewards and challenges. It can be a fulfilling time of rest and relaxation; enjoying respite from a life of working and raising children. It is also a time when the body starts its graceful decline. Unfortunately, this decline can bring various health problems, for instance loss of muscle mass. Age-related loss of muscle mass and strength is called sarcopenia.
Functional loss of muscle strength with age is not only associated with diminished quality of life and problems with activities of daily living; it can have serious effects including increased risk of falls, fractures, disability, hospitalisation and death. As well as aging, chronic diseases like diabetes factor among sarcopenia causes.
A recent review now suggests sarcopenia could even lead to type 2 diabetes.
Type 2 diabetes in Australia
Around 1 in 6 Australians over 65 suffer from diabetes, increasing to nearly 1 in 5 adults over 85. Type 2 diabetes makes up 90% of all cases, affecting one million Australians, 90% of whom are over 40. Unlike type 1 diabetes, an autoimmune disease, type 2 is associated with unhealthy lifestyle factors like poor diet, inactivity, smoking and obesity, and is therefore preventable.
Diabetes happens when there is too much glucose in the blood – either because the pancreas stops producing enough insulin (needed by most tissues to take up glucose), and/or because cells lose their capacity to take up glucose (become insulin resistant).
This can happen when the body is bombarded with too much sugar or refined carbohydrates, and the glucose receptors that let sugar into cells go on strike. The pancreas keeps producing insulin to try and lower blood sugar, and eventually wears itself out.
The body then goes into overdrive trying to keep blood sugar levels down, and the strain can cause a plethora of serious problems include heart attack, stroke, kidney damage, vision loss, nerve damage and poor wound healing – which can also result in amputation of limbs.
How might sarcopenia cause diabetes?
Sarcopenia research has been dominated by functional outcomes. But a recent review drew attention to possible metabolic consequences, focussing on various pathways that could lead to diabetes:
- Skeletal muscle tissue is the most sensitive to insulin, as it uses around 80% of the body’s glucose for storage and energy. Therefore, muscle loss with age leads to lower glucose storage capacity, hence less insulin receptors to allow cells to take up glucose.
- Aging and sarcopenia result in loss of muscle quality, leading to oxidation and inflammation, both associated with insulin resistance.
- Infiltration of muscle by fat also occurs with age, and can lead to insulin resistance.
- Lower physical activity is another contributor, as exercise mobilises muscle cell receptors that can take up glucose.
Preventing muscle loss
Therefore, the importance of preventing or reducing muscle loss and chronic disease with age cannot be understated. Prime targets are diet quality – particularly protein and vitamin D for muscle and generally a healthy diet to prevent chronic disease – and appropriately tailored physical activity.