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Why Does Diabetes Lead to Limb Amputations?



The International Diabetes Federation estimated around 10.5% of the global adult population (ages 20-79) had diabetes in 2021, or around 536 million people. That number is expected to rise to 12.2%, or 783 million people, by 2045.


Of all the problems it causes – for example, kidney damage, eye damage, increased risk of stroke, and impaired immunity – perhaps the most notorious complication of diabetes is lower extremity amputations.

  • The statistics around this issue are truly frightening:

  • Every 20 seconds, someone loses a limb or part of a limb to diabetes.

  • From 2009 to 2019, hospital admissions related to amputations for diabetic patients doubled

  • Around 80% of lower extremity amputations in the US result from complications of diabetes, not traumatic accidents

  • People with diabetes are thirty times more likely to have an amputation in their lifetimes than people without diabetes

This article is a brief primer on why amputation can happen to diabetic patients.


So, what’s the science?

Diabetes mellitus, a metabolic illness that occurs when the body cannot make or use insulin to regulate its blood sugar, causes dysregulation in multiple body systems. Without insulin, glucose (sugar) has no way of getting to the cells that need it.


Unable to absorb into the right tissues, unused glucose automatically heads to other places – such as blood vessels, red blood cells, and nerves -- which do not need insulin to absorb glucose. Importantly, these other tissues also have no way to keep from absorbing too much glucose, leading to cell and tissue damage.


Glucose usually binds to proteins, lipids, and nucleic acids in a manner that is reversible. Persistently elevated blood sugar levels also glucose to form permanent bonds with those structures, leading to proteins becoming trapped and linking together in ways that cause further damage, including inflammation, thickening of blood vessels, and prohibiting blood vessels from expanding normally (vasodilation).


As a result, less oxygen from the blood is able to get to body tissues, especially those in the lower limbs and feet.


Less oxygen to the lower limbs means that the nerves responsible for moving the muscles, controlling sensation, and regulating blood flow can be further damaged. This dulls the nervous system signals coming from the brain and spinal cord. The diabetic individual is, therefore, at risk for reduced or nonexistent pain in the lower legs and feet, meaning that they may not recognize a foot injury until it’s too late.


Furthermore, the diabetic person is at risk for foot and lower limb deformities due to loss of muscle control, as well as severe overdrying of the skin (xerosis) that leads to cracks, calluses, fissures, and ulcers.


Most diabetic foot ulcers happen because vulnerable spots in the feet, which the person may not be able to feel, are put under constant pressure from walking. Calluses or blisters typically form first, and once the damage is severe enough, an ulcer forms.


Diabetic foot ulcers are infamous for their delayed and difficult healing process. Diabetes directly increases the risk of infection through diminishing blood flow, white blood cells, and oxygen to the wound. Some invading pathogens can feed on high blood sugar levels in the tissues around the wound, causing infection to spread rapidly.


Even worse, an impaired immune system response may prevent a diabetic wound from showing symptoms of infection. Using diabetic wounds as an entry point, pathogens are often able to cause infection in the bones. Unfortunately, when infection cannot be controlled by other means, such as intravenous medication, or when the tissue loses so much oxygen that it dies, amputation is the final option.


The good news is that around half of amputations due to diabetes are preventable. Some ways to prevent amputations for diabetic people are:

  • Washing (not soaking) the feet daily

  • Applying moisturizer to the feet after bathing, but not between the toes

  • Not walking barefoot

  • Avoiding footwear with pointed toes

  • Avoiding socks that are too tight or are made of nylon

  • Checking the feet and lower limbs every day for overly dry skin, blisters, calluses, and wounds

  • Making sure footwear fits correctly. The diabetic person may need special footwear

  • Noting any areas on the foot, heel, or ankle that are vulnerable to pressure

  • Keeping pressure off existing calluses or wounds

  • Avoiding heating pads or hot water bottles for cold feet (can cause burns)

  • Not cutting the toenails too short

  • Filing toenails to keep them from cutting into the toes

  • Avoiding the use of razor blades, chemicals, or corn pads on the feet (can cause injury or burns)

  • Regular visits with a podiatrist or diabetic foot care specialist


For more patient and caregiver resources, visit the American Diabetes Association.


References

Assessed and Endorsed by the MedReport Medical Review Board

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