Nutrition & Type 2 Diabetes
Updated: Jan 14, 2021
This week has marked National Diabetes Week 2020. The purpose of this week is to raise awareness of diabetes and to help those who suffer with this disease; in addition, this week will help raise money so that important research can take place, enabling us to tackle this disease head on and improve the quality of life of many millions of people all around the world.
To mark this week, in this blog post I will be specifically focusing on type 2 diabetes and the role that nutrition plays in both the cause and the treatment of this chronic disease.
How does diet influence this disease and how can we potentially manipulate our diet to treat it?
Let’s start at the beginning, what is diabetes?
Diabetes is a group of chronic diseases which are all characterised by high levels of glucose in our blood after consuming a meal. Under normal conditions in healthy people, after we digest a meal, we absorb carbohydrates in the form of simple sugars, including glucose. This causes a rise in our concentration of glucose in our blood.
Our blood glucose concentration must be kept within a certain range otherwise it can be very toxic for our cells and tissues. Our bodies specific processes which regulates the blood glucose levels. When we eat food, these mechanisms increase the amount of glucose that we absorb into our cells, decreasing the concentration in the blood.
Between meals, when our blood glucose concentration drops, there are opposite mechanisms which cause more glucose to be exported back into our blood, to raise the glucose levels to the appropriate amount once more.
These mechanisms do not function properly in people with diabetes. This means that they have continuously high levels of blood glucose, especially after consuming food. This can have many varying detrimental health consequences; including blindness (caused by the high blood sugar levels damaging the retina of the eye) and cardiovascular disease which increases the risk of heart attacks and strokes which can therefore result in death.
Specific molecules involved in regulating our blood glucose concentration
Insulin – released from beta-cells in our pancreas in response to high levels of glucose in our blood. Insulin causes our muscle and liver cells to take up more glucose from the blood and store it in the form of glycogen.
Glucagon – released from alpha-cells in our pancreas in response to low levels of glucose in our blood. Glucagon causes our cells to breakdown the glycogen to form glucose again, which is then released back into our blood to increase the glucose concentrations back up to the normal amounts.
About type 2 diabetes
There are several different types of diabetes, each are characterised by hyperglycaemia (the high blood sugar levels). However, the mechanisms behind why this happens are different.
Type 2 diabetes is usually acquired later in life. In this form, the muscle and liver cells do not recognise the insulin when it binds to them. This means they do not respond to the insulin by taking up more glucose from the blood, leading to sustained high blood sugar levels.
Because insulin does not work in these patients, the body compensates by causing the pancreas to produce and release lots more of it. This sounds like a good thing, right? Wrong. Its these high levels of circulating insulin that can have many detrimental health effects. The high levels of insulin in the blood can cause damage to our blood vessels and cause our blood pressure to increase; both of which can cause an increase in the risk of stroke and other cardiovascular complications.
Type 2 diabetes is a progressive disease. Insulin insensitivity is one of the first stages, as described above where your tissues don’t respond to insulin. This is also known as a pre-diabetic state.
However, as time goes on, if the disease is not diagnosed and treated accordingly then insulin insensitivity can lead to insulin resistance. Eventually the beta-cells cannot keep producing the large amounts of insulin that is needed to control the blood sugar levels; this results in the failure of these cells. This means that no insulin will be released from the beta-cells anymore.
How does type 2 diabetes start?
We are not 100% sure how type 2 diabetes starts exactly. What we do know however, is that there is a complex interaction between our genes, and the environment we live in. What I mean by this is the food environment in which we live in, our economic status, the jobs we have and how active we are. All of these things influence the food that we eat.
What we do know however, is that type 2 diabetes is associated with obesity. It is thought that it is the increase in abdominal fat and the fat that is stored in places where it should not be (the liver and the muscles) that starts the cascade leading towards insulin resistance. There is also evidence that fat build-up in the pancreas is associated with the onset of diabetes and this may lead to the failure of the beta-cells.
Western diets are often associated with obesity and type 2 diabetes. These diets are usually high in processed foods and free sugars (added sugar to food such as cakes and biscuits) and also high in saturated fat. There has been a multitude of studies suggesting that diets that are high in whole grains, lots of fruits and vegetables and polyunsaturated fats (fats found in fish and vegetable oil) have a protective effect against obesity and therefore type 2 diabetes. These diets may prevent the fat from accumulating in the abdominal region and also prevent it from being stored in the tissues that are not meant to store it (1).
DISCLAIMER ALERT – I am not advertising that we should not be eating foods such as cake and biscuits, but we should be aware that consuming high proportions these types of foods may increase the risk of and developing type 2 diabetes. However as mentioned above, diet is not the only factor that causes someone to develop type 2 diabetes, there are many other factors associated with it including our gender, age and ethnicity.
Many trials have been undertaken looking at lifestyle interventions which incorporate dietary advice and increased physical activity to prevent, treat and manage type 2 diabetes. This is because of the association between obesity and type 2 diabetes.
Nutrition and prevention of diabetes
There have been several long-term randomised intervention trials that look at the effect of dietary advice coupled with increased physical activity and the prevention diabetes. These interventions are often compared to a control (a standard intervention that one may receive on the NHS) and the use of an anti-diabetic drug.
An American study called the Diabetes Prevention Program involved 3,234 men and women who had pre-diabetes (2). They were randomly split into three different groups.
Intensive lifestyle program group. This incorporated dietary and physical activity advice in 1-on-1 sessions every 2 weeks for 24 weeks and then once a month for the rest of the study.
Standard lifestyle advice group. This group had once yearly 1-on-1 sessions.
Metformin alongside the standard lifestyle advice. Metformin is an anti-diabetes drug which works by helping the individual to control their high blood sugar levels.
The dietary advice used for both the standard and the intensive lifestyle intervention groups was a low calorie and low-fat diet. These low-calorie diets are specially formulated for individuals who are severely overweight and should not be used by the general public without any support from a registered dietitian.
This was a very large study that spanned over a total of 4 years. This study is therefore classed as a relatively long-term study; this is good as it enables us to see what the long-term effects are of these different interventions compared to the use of the anti-diabetes drug.
Before looking in depth at these results, I assumed that the drug must be the most effective way of preventing diabetes, otherwise why would we prescribe it? I was very wrong. The metformin (drug) group did lose some weight, however over a 4-year period this was insignificant. The drug did however enable a 31% decrease in the risk of developing diabetes.
Over the 4 years the intensive lifestyle intervention group lost more weight and were able to sustain this weight loss, in addition to having a 58% decreased risk of developing diabetes at the 4-year mark.
At the end of the 4 years the number of individuals who had diabetes were measured. In the intensive lifestyle group 4.5% had diabetes, in the metformin group this was 7.8%, however in the standard lifestyle intervention group, this was 11%.
This study therefore highlights the contribution that weight has on diabetes and how important it is for those who are overweight and are diagnosed with pre-diabetes to lose some weight. Therefore, these 1-on-1 sessions with a health professional are essential to help those most at risk of diabetes to help them to decrease their risk of becoming seriously ill with this disease.
But what can be done for those who have already progressed to being diagnosed as diabetic and suffer from insulin resistance?
How to manage and control diabetes through diet
Like with the diabetes prevention studies, there are several long-term studies which look at the most effective ways to treat and manage diabetes.
The historic way that diabetics were told to manage their diabetes was through limiting and controlling their carbohydrate intake. However, after many studies and the collection of a lot of strong evidence, we now understand that the best and most effective way is actually through lifestyle interventions, similar to those used for the prevention of diabetes.
These interventions have shown that losing weight can help improve the fasting blood glucose concentration (the concentration of sugar in the blood before we eat), which is normally very high in people with diabetes. This improved control over blood glucose concentration ultimately translates into a reduced risk of developing the health complications associated with diabetes such as cardiovascular disease.
A study published in 2017 focused on a very restrictive calorie diet and how this may cause remission of diabetes (3). 306 men and women who suffered from type 2 diabetes and who were classed as overweight or obese took part in this study. The study group revolved around a very low-calorie diet consisting of the consumption of only 830 kcal per day. This very low-calorie diet was achieved through milk shakes and soups.
24% of those in the intervention group managed to achieve the 15% weight loss which the study was aiming for, compared to 0% in the control group (a standard lifestyle intervention). What was staggering from these results is that 46% of those in the very low-calorie diet group achieved diabetes remission, compared to just 4% in the control group.
This study therefore shows how once again interventions that focus on our lifestyle can have a huge impact on our health.
But do these lifestyle interventions work for everyone?
These lifestyle interventions will only be successful if people change their behaviour. It usually incorporates huge changes in habitual behaviour and often requires a huge amount of self-motivation. This can be extremely hard for some people to achieve.
Therefore unfortunately, for many people suffering from diabetes, these lifestyle interventions may not be effective. This is why there are drugs currently available. These drugs help people to control their blood sugar levels after they have eaten via several different mechanisms, including helping the liver and muscle cells to take up more glucose.
The problem we have with these drugs is that diabetes is a progressive disease, meaning that it will just continually get worse. We have no drugs or other therapeutic interventions available at the moment that actually stop the progression of diabetes.
There is currently a lot of research being carried out focusing on new therapeutic approaches to treat type 2 diabetes which will halt the progression of the disease. These new drugs may ultimately allow those suffering from this chronic illness to reverse their hyperglycaemia and the associated health consequences.
But for now…
For those suffering from diabetes, lifestyle interventions coupled with the use of anti-diabetic drugs, seems to be the best option. However, it is important to note that individuals should always first seek advice form a GP and/or clinical dietitian.
Evidence also suggests we can prevent more cases of diabetes by leading happy and healthy lifestyles. We can minimise our risk of developing diabetes through consuming a well varied diet full of wholegrains, fruits and vegetables, alongside regular movement; whether this is walking, jogging, swimming…the list goes on.
But let’s not forget that food is there too be enjoyed, so please eat the things that you love! If that means cake and chocolate (like me!), then make sure you incorporate these in moderation into your diet too.
Above all… EAT HAPPY & LIVE WELL
Salas-Salvadó J, Bulló M, Estruch R, Ros E, Covas M-I, Ibarrola-Jurado N, et al. Prevention of Diabetes With Mediterranean Diets. Annals of Internal Medicine. 2014;160(1):1-10.
Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin. New England Journal of Medicine. 2002;346(6):393-403.
Lean MEJ, Leslie WS, Barnes AC, Brosnahan N, Thom G, McCombie L, et al. Primary care-led weight management for remission of type 2 diabetes (DiRECT): an open-label, cluster-randomised trial. The Lancet. 2018;391(10120):541-51.