Diabetes mellitus and the foot

What is diabetes mellitus?

Diabetes mellitus (or diabetes) is a metabolic disease resulting from too much sugar being in the blood. Levels of sugar within the bloodstream are referred to as the blood glucose level, and in diabetes that level is too high. After eating, blood sugar levels rise. However, they should soon drop as the sugar is removed from the blood to feed the tissues of the body with energy that keeps them alive. 

Being a metabolic disease means that diabetes is a disease that changes how the body uses the energy that is supplied to it by eating food. The food we eat contains the molecules (energy) required for living. The energy contained in food allows tissues to grow, repair and be maintained to stay alive. After eating, the energy in food is absorbed by digestion and fed into the bloodstream. It is then pumped to all the different body tissues for its use as necessary. If we do not eat sufficiently, we lack enough energy to thrive and this can result in starvation and death. Living processes such as walking, breathing, and blood pumping all require energy. This energy is extracted from food in much the same way that gas, wood, coal or petrol is set on fire to release energy to keep a house warm or drive an engine. It is all just a matter of changing stored or potential energy (food, coal, petrol) into obvious energy like heat and motion.

All food contains energy, but some food contains very high amounts of energy that is easily extracted during digestion. Foods with lots of sugars (known as carbohydrates) are particularly good for providing energy quickly. When in small quantities, there is no problem with this as the body can quickly use up such energy in the normal daily activities of living. If absorbed amounts of sugars are too high to use immediately, sugars can be converted and stored as fat to be used later when energy demands are higher. Muscle and liver tissues are particularly important for regulating sugar levels within the body.

Problems arise when activity levels are low but access to carbohydrates is high. Some high-carbohydrate foods are better than others. Foods with complex carbohydrates have higher fibre content. These foods release their sugars more slowly during digestion. Food and drinks made of simple carbohydrates make them sweet and tasty, but they raise the levels of sugars in the blood very quickly. These are the most dangerous to consume. However, too many carbohydrates from any source can be a problem.

Figure 1. Bread and potatoes contain carbohydrates that are harder to digest than more processed foods like beer, pop, pizza, and chocolate. However, if any starchy foods like pasta or rice are over-eaten they can be just as dangerous as more obviously sugary foods.

Over-eating carbohydrate foods causes the body to have too much energy compared to that being used. Some can be converted to fat for later use. However, if sugar is left in the bloodstream too long, it causes chemical changes to the very structure of the tissues across the body. Inactivity makes this more likely to happen as we use up less energy within our muscles if we live a sedentary life. More frequently used muscles will burn up more energy, even when they are at rest.

Figure 2. Modern living promotes the conditions for the development of diabetes.

 

Diabetes damages collagen and causes premature ageing

The chemical change caused by too much sugar in tissues is known as, glycation. This is the process where sugars become attached to the proteins and fats used to construct body tissues. The bonding of sugar to body tissues forms advanced glycation end products or AGEs. 

There are two important processes behind the reasons that the body naturally ages. These are called oxidation and glycation. It is the later process through the making of AGEs, that is linked to excess sugar. If the body receives too much sugar, the body starts to age very rapidly through accelerated production of AGEs. AGEs alter the nature of the primary protein that forms the body tissues, which is called collagen. 

Collagen is a stiff protein that forms twisted elastic fibres similar to how steel rods can be coiled into springs. Collagen is in all tissues and where it forms into fibres, it makes them strong and elastic. When people are young, fibres only have a few cross-links between them, allowing each fibre to easily stretch and slide past the others as they are tensioned by movement. With ageing, the cross-linkage between fibres increases which increases stiffness and reduces elasticity. You can see the effect of this when you stretch a child’s or young adult’s skin and compare it to an older person’s more wrinkled and less elastic skin.

Figure 3. The springy nature of healthy collagen. 

AGEs-altered collagen causes the premature and aggressive development of diseases we associate with old age. AGEs change the very function and material properties of the tissues. These effects are associated with the behaviour of wrinkly old skin, but the processes occur in all body tissues such as ligaments, tendons, blood vessels, and even bone. Tissues become stiffer and more brittle as we age.

Figure 4. The loss of springiness and the stiffening of diabetic collagen.

This is a natural part of ageing, but developing more AGEs produced by having diabetes means that tissues age incredibly rapidly at an earlier age. The result is that vascular disease, fragile skin, weak muscles and bones, and more brittle tissues dramatically increase the risk of injury and diease. The immune and healing processes are also suppressed, so once an injury occurs, healing is very slow and infection is far more likely.

Fig 5. The factors that cause diabetes and the results of having diabetes.

 

Who can get diabetes?

Everyone is at risk of developing diabetes mellitus if they perform insufficient exercise and eat lots of high-energy foods. It is a case of filling the body with too much fuel without the capacity to store it safely! It is a dangerous thing to do.

However, some people are more at risk than others because of difficulties in the use or manufacturing of a hormone called insulin. Insulin is required to remove sugar from the blood and move it into the body tissues so that it can then be converted into energy to be used up or stored as fat. Normally, when sugar (glucose) levels in the blood are high, such as after eating, more insulin is released from a gland called the pancreas. Insulin promotes the movement of sugar into the tissues for use. If glucose in the blood drops too low, insulin is stopped and another hormone (glucagon) is released from the pancreas. This releases stored sugar from the liver, raising the glucose level in the blood. This balance between the two hormones by the pancreas makes sure that there is always enough but not too much, energy for the body to use. However, muscles and the liver also play an important part in keeping glucose at the required level.

Figure 6. Insulin and glucagon hormones control the blood glucose levels between them.

Some people have insufficient levels of insulin as a result of autoimmune problems. This causes damage to the special areas within the pancreas that make insulin by abnormal immune processes. The resulting damage causes a stop to or severely reduces insulin production. This is associated with a type of diabetes called type-1, which tends to affect younger people including children.

Figure 7.  The loss of glucose control with low insulin levels.

Other people can develop tissues that become more resistant to the beneficial effects of insulin and as a result, they cannot remove glucose from the blood as easily as normal. The pancreas responds by making even more insulin to counteract this problem and as long as levels are kept high enough to overcome the tissues’ weak response, blood sugar levels can remain normal. But, if for any reason insulin levels cannot be maintained, diabetes develops.

However, the most common form of diabetes results from there being too much sugar in the blood from overeating carbohydrates for the production of insulin to manage. Overweight and obese people are most commonly affected, particularly if their muscle mass is low. Therefore, the body has to make far more insulin to control the higher levels of sugar resulting from consuming too much food. 

What does not help in both of these situations is that the higher production of insulin which is now necessary to manage the high-sugar levels, can drop. This is because the cells that make insulin within the pancreas, can start to ‘burn out’ through overproduction. Again, having lower amounts of muscle tissues makes this more likely because muscles require lots of energy and also produce chemicals that help control glucose levels. 

Being resistant to insulin or being overweight causes a form of diabetes called type 2 or late-onset diabetes. It is generally associated with older people. However, with the drop in many children’s activity levels and the rapid rise in childhood obesity, coupled with the increase in processed carbohydrates within the modern diet, type-2 diabetes has become the most common type of diabetes diagnosed in kids. Its incidence is rising rapidly. Sadly, being a child does not protect you from premature ageing damage from diabetes, so children start to develop vascular (blood vessel) disease, weaker muscles and tendons, and poor nerve function (neuropathy) at a much earlier age. This is a terrible situation for their well-being and life expectancy.

Figure 8. The result of tissues becoming resistant to the effects of insulin is the most common form of diabetes now generating problems. However, the root of the problem is certain lifestyle choices.

 

Why is the foot a problem in diabetes?

Too much sugar in the blood causes glycation-induced chemical changes that prevent normal tissue function. Smaller nerves lose the ability to send information (neuropathy), ligaments, tendons and bone become more brittle, muscle power reduces and wastes away, small blood vessels start to become blocked and skin becomes more fragile. Complex tissues within the eyes are particularly vulnerable to glycation, explaining why blindness is so common among diabetics. The immune system and the cells used for healing also become compromised, preventing an effective response to any local injury and bacterial infections.  

The foot is composed of 28 bones, multiple ligaments, tendons, muscles, and lots of small nerves. Finally, the foot is covered in thicker skin than that found elsewhere and the foot’s blood supply is a long way away from the heart. The foot is the only part of the body built for ground impact with every step, explaining why it has thicker skin. This means the foot is subjected to a lot of external forces and it is very reliant on its nerves to alert the body to any potential events that might cause injuries. Also, nerves and muscles between them, help set the correct levels of shock absorption across the many joints of the foot. Loss of normal nerve function is called neuropathy, and when the fine nerves in the limbs are affected it is called peripheral neuropathy.

Glycation-induced peripheral neuropathy also causes loss of nerve control of both the amount of blood flowing into and out of the foot, as well as muscle activity. There is also loss of sensation, so tissue injury and irritation are not felt and action is not taken to avoid a damaged area or prevent something from being over-stressed. Often a diabetic is unaware of shoes rubbing on the toes. Muscles in the foot become weaker due to the loss of their normal structure, while the normally elastic tendons and ligaments also become internally stiffer and weaker. Together this reduces the shock-absorbing capacity of the foot. The damage caused by all these changes in tissue properties is not felt because the nerves are not working properly. As a result of weaker bones and stiffer tendons and ligaments, the soft tissues can start to be pulled off the bones they attach to, bones which are also more likely to fracture. The foot can then start to deform and may develop into a very flat, or rocker-bottom foot known as a Charcot Foot.

This change in the material properties and structure of the foot exposes the skin to higher stresses than normal, yet diabetic skin is also abnormal being less elastic and more fragile than healthy skin. As a result of poor shock-absorption capacity across the deeper foot structures and often because of toe and foot deformity from the altered tissue mechanics, the more delicate diabetic skin can eventually fail. As the skin becomes damaged the diabetes-induced compromised healing process cannot heal the wound properly, causing an ulcer. This allows bacteria to freely infect these wounds, which the diabetes-induced compromised immune system cannot kill. Often, antibiotics are of little help because the foot’s circulation is too poor to allow the swallowed drug to reach the infection via the bloodstream, as it does normally. Adding to the problem of having an ulcer, a diabetic often cannot feel any pain to make them take action to prevent further damage.

Once ulcers and foot deformities start, the diabetic foot becomes a very difficult problem to manage. In time, parts of the foot or the whole of the foot, or the leg below the knee, have to be amputated. This increases stresses on the opposite limb, which can then start causing increasing problems in the remaining leg that risk amputation of this limb too.

Figure 9. Some of the nasty effects of diabetes on feet.

You ‘really’ do not want to become a diabetic. 

However, if you have diabetes you need to take it very seriously and initiate action to protect your feet and try and resolve or limit the damage taking place.

 

Can I improve or resolve my diabetes?

Yes, and yes! Mostly, this is up to you.

Although medication can be given to help manage diabetes, it will not cure it or reverse any damage caused by it. Each drug also has some potentially problematic side effects. 

Getting your own body to manage its natural systems of sugar processing again, is by far the best option.

If you have a blood test that shows you are diabetic or pre-diabetic as a result of type-2 diabetes, you can stop this dreadful disease by taking immediate action.

You MUST change your diet and increase your amount of regular exercise. Good food choices include green vegetables, salads, eggs, unprocessed meat, berries, seeds, and fish, especially oily ones like mackerel. 

Figure 10. Just some of the healthier food options that help to reduce the risk of diabetes.

If you can start to work your muscles more, they will help to manage your blood glucose level. Walking and running are simple options that require little equipment and a little mixing of these two exercises for 20 minutes two or three times a day, will make a huge impact in reducing the risk of diabetes. if you don’t feel you can run, just stick to walking but occasionally at a pace that gets your blood pumping and increases your breathing rate.

Figure 11. Find the exercise that best suits you and that you enjoy the most and do it daily.

Reducing the sugars coming into the body makes it easier for muscles to manage and use all the sugars up through increased activity. That is why it is so important to exercise and change your diet, together. Muscles will burn up the sugar and less sugar makes it easier for muscles to achieve this balance.

Figure 12. Eating the correct foods most of the time combined with daily exercise is the solution to preventing, resolving or improving diabetes.

The longer you have had diabetes the harder it is to start to gain improvements. Part of the reason for this is because of the diabetes-induced damage to muscle tissues that has already occurred. However, there are still benefits to be gained even if you have been diabetic for years.

There is much advice about diet for diabetics across the internet, but you should be put in contact with a dietician once you have a blood test that flags up the issue of pre-diabetes or actual diabetes. Listen very carefully and take their advice. No buts…., for you must choose the solutions offered that work best for your lifestyle. that makes it easier to stick to the plan.

Exercise is easy because every type of exercise works. If you don’t have a favourite type of exercise and/or do not want to go to a gym, just go walking. This is the cheapest exercise available, the least likely to cause an injury, and it can be achieved by just going out of your front door and moving. 

You only need to walk for around 20 minutes twice daily to make a considerable difference as only 8 thousand steps a day are required to keep much fitter, keep muscles working, and improve your fitness and balance. You just need to be consistent. Of course, gradually increasing the distance, speed, and frequency over time, is even better. For more information visit NHS Walking for Health.

Figure 13. Walking 20 minutes twice a day is not hard to do.

Try and make walking a pleasure. Walking improves both mental health and physical health. However, when walking is performed in green spaces, the mental health benefits will be much better. In cities, parks are ideal, as are canal towpaths. For those in the suburbs or countryside, there are plenty of footpaths to access nearby. If suitable, consider getting an active type of dog, as they are companions that force you to walk.

Consider joining a walking group for health, such as The Rambler’s Association’s ‘wellbeing walks’ in England and Wales or in Scotland.

This will allow you to meet, chat and walk with other like-minded people with similar health issues.

 

How can I protect my foot as a diabetic? 

There are significant changes in how both the ankle and foot function associated with diabetes. This is due to a reduction in the freedom of joints to move resulting from the stiffening of tissues from glycation. This reduction in motion combined with weaker muscles and bones, and the reduced ability to shock-absorb, means that protecting the foot is a good idea. By doing so, you can help prevent deformity and ulceration.

Footwear

First and foremost, make sure that shoes fit perfectly. Be aware that with age, feet often get a little longer and wider so it is worth getting each foot measured again. However, diabetes can sometimes cause the foot to become shorter and more highly-arched because of neuropathy and changes in the flexibility of ligaments, and tendons. Therefore, your shoe size might have gone up or down. Getting the correct fit is very important. This is a fundamental issue for protecting diabetic feet.

Slip-on shoes are not a suitable choice because, by their very nature, they must be tight.

Figure 14. Slip-on shoes like ballet pumps are not suitable for diabetic feet.

Lace-up shoes with deep rounded toe boxes that do not press on the toes or upon the forefoot are the best choice. Velcro is an alternative for those unable to lace shoes. 

Trainer-type shoes tend to be manufactured with shock-absorbing materials and soft uppers (top parts). Trainers are usually quite light and lace-up, and many have a removable insole making them an excellent choice. Other shoes having a rounded toe-box shaped like a trainer, may also prove suitable.

Figure 15. Lace-up trainers offer lots of potential benefits for diabetic feet, especially if they only bend freely around the toe joints.

 

Insoles/foot orthoses

Foot orthoses is the medical term used for insoles. They can protect a diabetic foot by increasing the foot’s contact surface area across its contoured ‘arch-supporting’ profile. Increasing the amount of the bottom of the foot (plantar surface) in contact with the insole, allows them to reduce the highest pressures on the foot because pressure is the force over an area. Lower peak pressures will reduce the chance of damaging soft tissues deeper within the foot or injuring the skin.  By supporting the arch, insoles also help protect the foot from the damaging effects of limited ankle motion. They can also provide extra shock absorption if constructed with suitable materials.

Insoles provided by clinicians and therapists directly can be further constructed to your specific needs, either by creating a custom-manufactured insole or by adjusting a prefabricated insole, such as those manufactured by Healthy Step. 

The cost of custom insoles can be very high and as yet, there is no good research evidence suggesting that custom insoles built from the same materials as prefabricated devices, offer any better outcomes. Therefore, we advise that as long as you are not having issues with ulcers, you can try insoles such as the XLine Pressure Perfect 

 

and see how you get on with them. If you have problems with your feet like ulcers, you should be referred to a specialist who can advise you on the best type of insoles for your particular issues.

Figure 16. Insoles like the ‘Pressure Perfect’ are very cost-effective foot orthoses that have been designed with the needs of the diabetic foot in mind.

 

Foot and calf exercises

Muscles are severely damaged by diabetes, with fat being abnormally deposited among muscle tissue, taking up the space where healthy muscle should be. Also, the remaining muscle tissue starts to become abnormal causing healthy muscle tissue areas to gradually become smaller. Although the only way to stop this process is to stop being diabetic, strengthening and exercising muscles will help to keep you moving and help the remaining healthy muscle tissue stay stronger.

Because connective tissues such as tendons and ligaments become stiffer and more brittle with diabetes, maintaining normal ranges of joint motion is important. This is particularly true regarding ankle forward motion (known as dorsiflexion). During walking, body weight has to move forward over the foot before we can make the next step. If the ankle is unable to dorsiflex freely, it creates considerable force over the top of the foot that squashes the arch downwards. This can injure the soft tissues under the foot bones. Diabetes is well known to cause loss of free ankle dorsiflexion. Fighting against this loss is very important and motion can be improved with the correct exercises. 

In certain circumstances, abnormal blood flow and lack of feeling resulting from damage to the nerve supply (neuropathy) found in some diabetics, can result in the foot becoming severely deformed and flattened when ankle joint motion is limited. These feet are called Charcot’s feet and they can be very disabling. 

Therefore, using well-fitted footwear, using supportive insoles designed for diabetics, and maintaining strength and flexibility are together extremely important. At HealthyStep we recommend the following calf exercises:

 

and the following foot exercises: