Humans today are leading a more sedentary lifestyle. Moreover, the typical urbanised diet is rich in refined sugars and processed foods. Our lifestyle choices have led to an obesity epidemic. And to top it all, obesity is now recognised as the primary cause of insulin resistance and type II diabetes.
What is the big deal with blood glucose levels?
In all mammals, glucose is a very important fuel to produce energy. The normal blood glucose range in humans should be between 4.5 and 5.5 mmol/l. A key regulator of blood glucose concentrations is the hormone insulin, secreted by the pancreas. Various organs in the body, such as the brain, rely on a constant supply of glucose, with mechanisms in place to ensure a constant supply. In a fasted state, the liver can make glucose from a process called gluconeogenesis and release it into the blood stream.
Eating carbohydrate (e.g. the sugar in your tea, starchy foods) is another means of replenishing glucose. However, this eating of carbohydrate results in a major spike in blood glucose levels, and it is this high level of glucose that can cause problems. Thus, the pancreas secretes insulin that allows tissues, especially fat and skeletal muscle, to rapidly take up the excess glucose, resulting in blood glucose concentrations returning to normal.
What brings about insulin resistance and type II diabetes?
To effectively lower blood glucose, insulin needs to bind to insulin receptors located on the outside membrane of fat and skeletal muscle cells. Once bound, it signals for these tissues to start taking up the glucose into the cells. The term insulin resistance means that the hormone insulin is not effective enough to lower blood glucose. This is not from low insulin concentrations, but rather that some of the insulin receptors located on the membranes of the cells, does not work anymore. The result is that it takes longer for the blood glucose levels to return to normal, which can have other negative effects on the body.
The primary reason for the insulin receptor destruction is frequently high concentrations of blood glucose. In other words, eating too frequently during the day and too much of certain foods can lead to insulin resistance. There are various degrees of insulin resistance and the good news is that it can be reversed. On the other hand, if there is no intervention, the pancreas cells that produce the insulin, starts to fail, eventually leading to no insulin secretion. This latter is called type II diabetes.
What about animals?
Interestingly, the incidence of overweight and obesity has similarly infiltrated the animal kingdom – from domestic pets to wild animals in zoos, those in sanctuaries or those roaming around freely. A major contributing factor to this rise in overweight animals is that their nutritional needs are poorly understood. This lack in knowledge may therefore lead to the overfeeding of animals in captivity with devastating consequences.
Some animals are very smart in finding palatable foods (e.g. racoons and non-human primates such as baboons and monkeys). Once they find a source of tasty food (e.g. breads, biscuits, sugar, etc.) they often become addicted and sow havoc in urban areas – to no fault of themselves. However, very little is known whether overfeeding may lead to diseases similar to that observed in humans.
The MyoLab is currently using innovative techniques to study obesity and insulin resistance in various animals species to help understand how this disease comes about, and how it may be cured.