Insulin as a lock and key

Characterised by insulin resistance and deficiency, Type 2 Diabetes leads to increased levels of glucose in the blood. Chronic levels of hyperglycaemia (high blood glucose) and increased free fatty acids (from adipose/fat tissue) are known to increase insulin resistance. But what does this all mean?

 

Similar to a lock and key system, insulin is a hormone made by the pancreas. It allows the body to use glucose (sugar) for energy. The key (insulin) is needed to unlock pathways which are required for the glucose to enter different systems in the body, most notably our musculoskeletal system. By allowing glucose into the muscle, insulin can maintain appropriate levels of glucose in the blood so that levels don’t go too high (hyperglycaemia), or too low (hypoglycaemia).

 

When the lock and key doesn’t work

When we consume sugary food or drinks, the pancreas releases insulin to clear glucose from the blood. Insulin resistance is when the body’s cells become desensitised to the presence of insulin, and cannot use it as a key to effectively allow glucose into the cell. When we continue to consume in excessive amounts, over and over, the pancreas releases more and more insulin to compensate. Over time, the cells become resistant to the presence of insulin and eventually the pancreas becomes burnt out and insulin production decreases. As a result, glucose stays in the blood, and the body experiences glucose intolerance. Glucose intolerance is the inability to remove glucose, resulting in hyperglycaemia.

 

Exercise and insulin

Exercise can improve insulin sensitivity. This is the body’s ability to recognise and use insulin to remove glucose from the blood. As a result, blood glucose levels are lowered (improved glucose tolerance), and glucose is used for energy or stored by the liver for later use.

*** Added benefit: During exercise, the muscles can take glucose from the blood without the use the insulin, further lowering blood glucose levels.

 

Exercise and Glucose tolerance

Research shows that improved glucose tolerance deteriorates within 72 hours of the last exercise session. This highlights the importance of exercising regularly. In addition to maintaining control of your disease, the risk of all-cause mortality decreases as your levels of fitness improve. Interestingly, this only requires a moderate improvement in fitness!

 

Exercise and Insulin Sensitivity

Following bouts of training, sensitivity to insulin improves and adipose (fat) and skeletal muscle tissue is better able to take in blood glucose. This happens regardless of whether there are any changes in fat/muscle mass, lost or gained. Unfortunately, similar to the benefits of exercise for improving glucose tolerance, improved ability to detect and use also only lasts 72 hours. Therefore, regular activity is necessary to maintain improvement.

 

Other benefits of regular activity include:

• Reduced blood pressure (at rest and exercise)
• Improved blood flow and reduced demands on the heart, by improving the ability of the heart to pump blood to the body
• Improved ability of the body to take up and use oxygen
• Weight loss and weight control (NOTE: good nutrition and regular exercise combined are more effective than exercise alone)
• Reduced visceral fat (the dangerous kind)
• Reduced cardiovascular risk
• Decrease stress, improved mood state

 

 

Blog by Exercise Physiologist,

Emma Perry