There are a number of risk factors for the development of type 2 diabetes, some of which we can’t change, and some of which we can. In this blog we will talk about some of the non-modifiable and modifiable risk factors for the development of type 2 diabetes mellitus.
Non-modifiable risk factors
Our genetics ultimately determine who we are, from the colour of our eyes, to how tall we are, and even down to the risk of us developing type 2 diabetes mellitus (T2DM). There is a high chance that, at some time or another, you've been told that you look like one of your parents or one of your brothers or sisters. That is because who we are is passed down to us from our parents, and our grandparents, and our great great grandparents. Studies have found that there is a 40% increase in the risk of developing T2DM if one parent lives with the disease, and a 70% increase if both parents do.
The risk comes from changes in the parts of our DNA that play a key role in controlling our blood glucose levels. Some of these changes in our genes can reduce the ability of the pancreas to release insulin.
As we have discussed in some of our previous blogs, insulin acts like the key to open the locks on our cells to let glucose in to be used as energy. However, when not enough insulin can be released, there are not enough keys to open all the locks. As a consequence of the reduced release of insulin from this genetic change, blood glucose levels continue to increase. Over time, elevated levels of blood glucose increases the risk of developing T2DM.
As research surrounding diabetes has increased in recent times, our ethnicity has emerged as one of the greatest non-modifiable risk factors for the development of T2DM. In some cases this can in part be explained by differences in socioeconomics and access to healthcare in less developed parts of the world. Despite this, T2DM is up to 6 times more likely to develop in those of South Asian descent, and up to three times more likely in those of African and African-Caribbean descent.
While the exact cause of this increased risk among different ethnicities is not fully understood, again it is likely that our genetics that are passed down to us and determine who we are play a large role.
Studies have found that when compared to other ethnicities, individuals of South Asian descent are at a greater risk of experiencing insulin resistance at a younger age. This is thought to occur as those of South Asian backgrounds tend to have a genetic predisposition to having a slightly higher percentage of body fat compared to other ethnicities of the same age and height. Moreover, this body fat is often carried around the stomach. This leads to the build up of fat around the pancreas, which in turn leads to reduced production of insulin over time, resulting in an increased risk of T2DM.
It is estimated that approximately 25% of all adults aged 65 years and over live with T2DM. This is compared with just 0.2% of children aged 19 years and under. Looking at why this is the case, there are a number of factors that come into play.
As we age, our bodies naturally begin to function less efficiently than they did when we were younger. Our eyesight begins to decline, we begin to lose bone mineral density and our bodies take much longer to regenerate new cells and recover from illness and injury.
This decline is also true for the cells within our pancreas that produce insulin, which in turn is responsible for the increased prevalence of T2DM in the elderly.
Modifiable risk factors
Excess body weight
By now you may be well aware that our weight plays a large role in developing T2DM. Our body weight represents the balance between all of the energy taken in from the foods we eat and drink, and all of the energy that we expend during our daily life. Energy is measured in calories. Being overweight means that, over an extended time, the energy we have taken in has been more than the energy we have used.
Weight gain = ENERGY IN is greater than ENERGY OUT
The difference is usually small. It’s typically only 100-200 extra calories daily. However this can be increased significantly at certain times of the year such as festive seasons and holidays where we may relax our eating and drinking behaviours.
While this increase can be relatively small day to day, over time the number of excess calories becomes significant. For example, if you were to consume just 200 calories more than your body requires to maintain your weight, over 10 years this would total 730,000 extra calories! What's more this small excess number of calories could come from something as small as having just 2 extra biscuits per day.
However, much the same as having just 200 extra calories per day can increase the risk, making small changes such as cutting out those extra 2 biscuits can have the exact opposite effect and promote weight loss through a calorie deficit!
In recent years there has been a dramatic reduction in the levels of the general population's physical activity. It is estimated that 1 in 3 women, and 1 in 4 men are said to not undertake enough activity to stay healthy.
What's more, given the rise in interactive technology and our increased reliance on cars for journeys we once would previously have walked on, from 2001 the level of insufficient physical activity has increased from approximately 31% to 37% in high-income countries.
It is recommended that we all undertake at least 150 minutes of moderate-intensity, or 75 minutes of high-intensity activity per week.
Increasing physical activity has been found to reduce the risk of T2DM through a combination of factors. Not only can being active contribute to weight loss, but increased activity has the effect of increasing the body's sensitivity to insulin and reducing the period of time our blood glucose levels remain high.
Moreover, regular endurance based activities such as running, cycling or swimming, require your body to use fat for fuel. In doing so, such exercise has been found to independently reduce levels of visceral fat ( fat around the stomach area ). As we discussed in one of our previous blogs, one of the primary causes of T2DM comes from visceral fat surrounding the pancreas.
In the UK, 15% of people aged 18 years and over are said to be active smokers. This represents a statistically significant decline of more than 5% when compared to the number of active smokers in 2011. While this is a welcome decline, there are still some 7.2 million active smokers that are putting themselves at risk of T2DM.
Smokers are estimated to be 30% to 40% more likely to develop T2DM than nonsmokers. Cigarette smoke has been found to contain more than 7000 harmful chemicals, many of which can decrease the effectiveness of insulin as a result of inflammation and damage cells as a consequence of oxidative stress.
Additionally, the nicotine from smoking can reduce the effectiveness of insulin, resulting in active smokers finding it harder to manage blood glucose levels.
It’s no secret, stress is one of those inevitable emotions that we will all face at some time or another in our lives. Our emotions are largely controlled by chemical changes within our bodies. When stressed, our body recognises this as a fight or flight situation and releases hormones such as adrenaline, glucagon, and cortisol in order to give you a boost of energy to manage whatever situation you may be in. However, while your stress may not be the result of a fight or flight type situation, this is how our body recognises it.
These hormones have both the effect of causing an increase in blood glucose levels as well as a reduction in the effectiveness of insulin. This is said to occur as these hormones have the effect of both increasing the release of glucose into your blood to be used as energy, as well as reducing the ability of insulin to help with the uptake of glucose. This change is said to occur in many of the parts of our body that are not thought to be a priority in fight or flight situations in order to preserve energy for key areas.
Increased levels of cortisol from chronic stress have also been found to trigger unwanted overeating behaviours. When we eat and enjoy our food, the feeling of enjoyment comes from the release of dopamine, one of the pleasure hormones, within our brain. In those who are stressed, the release of dopamine from consuming highly palatable sugar and fat rich “comfort foods'' has the effect of dampening stress related responses and emotions.
While many people may not experience this desire for comfort foods during stress, for some it can become significant. Research has found that during periods of chronic stress, approximately 50% are susceptible to experiencing high levels of cortisol. Overtime, this can lead to prolonged levels of comfort eating and, ultimately, an increase in body weight and the development of T2DM.
While we are unable to change the non-modifiable risk factors that many of us live with, the risk of developing type 2 diabetes can be reduced regardless if you live with them or not. By being aware of what the primary modifiable factors you are able to act on, such as weight loss, you can both minimise the risk of developing type 2 diabetes, as well as help with its management if currently living with the condition.