Sparing the details, a colleague of mine recently had his big toe amputated due to diabetes. I wondered why being diabetic could lead to this as it’s common.
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Your feet and more specifically your toes are the furthest body part away from your heart. In diabetes, your body is unable to regulate sugar in your blood appropriately. People who are poorly controlled tend to have much higher levels of blood sugar. The further away your blood gets from the heart, the more affect the varying concentrations of metabolites (like sugar for diabetes, or uric acid crystals in gout) start messing around. The excess sugar can damage the smaller blood vessels causing them to fail to appropriately deliver oxygenated blood. When the nerves lose that oxygen they start to die as well.
Now here’s where it gets tricky. All of that in and of itself doesn’t cause the toes and feet to require amputation. That comes from the lack of sensation resulting in individuals not knowing something has happened. Toe nails grow too long and you cut the side of one your toes? Didn’t feel it so now you don’t know you have a problem. Rock stuck in your shoe? Didn’t feel it so now your heel is being worn down and you get an ulcer. These micro wounds that a normal healthy foot would have been able to detect or avoid now become infected. But guess what, YOU STILL CANT FEEL IT! So you’ve got an infected wound just festering, and unless you’re routinely checking your feet it could go undetected for days or weeks or months. It’s these wounds that, when they come in to the doctor to finally get it looked at, result in amputation becomes the tissue has died and as there’s no coming back and it will just continue to be a nidus for infection which can turn into sepsis which can turn into death.
It’s a culmination of different things. For starters, your feet get the least amount of blood versus the rest of your body, they are the furthest thing from your heart. Now, toss in diabetes which can affect blood circulation, and your feet now get less blood flow than before (assuming we’re talking about a person with unmanaged diabetes). Now, add in the nerve damage in the feet caused by unmanaged diabetes. Now, you have the conditions for slower healing and not feeling the injuries done to the feet.
I venture to guess most people don’t regularly check their feet unless they FEEL something wrong. Well, if we apply this to an unmanaged diabetic who has an unknown foot injury, then we are on the grounds for amputation (depending on how severe the injury is). Minor cuts can become sites for infections the body can’t fight off due to the poor blood flow in the feet. Allowing these infections to fester results in gangrene and then amputation.
All in all, the condition for amputations involves a few factors which are easier in diabetics and even the most well controlled diabetics are not immune to these conditions. As a type 2 diabetic of almost 24 years dealing with some other shit related to the disease (vision loss from retinopathy), we are more susceptible to things non-diabetics generally don’t have to worry about.
Imagine high blood sugar you get from diabetes as a saw being used to cut a tree. Anytime you have high blood sugar, that’s a cut into the tree. And if you have consistently high sugars, that’s a saw constantly cutting into the tree, trying to cut the tree down. That’s what happens to your blood vessels with diabetes, those high blood sugars will saw up your blood vessels, making it hard for blood to flow, and cut down your nerve endings, so you can’t feel that part of your body anymore.
So your feet are furthest away from your heart and have the hardest time getting adequate blood flow to begin with. If your blood vessels are all scarred up and you can’t feel that part of your body, then a simple wound to a toe can be devastating. There’s not enough blood flow to heal the wound, you may not even notice the wound thanks to those cut out nerve endings, and bacteria thrive in high blood sugar, and will swarm to the cut like ants to syrup. The best way to deal with this is to amputate so the bacteria can’t infect more places in the body. You’re cutting down a tree to save the forest.
Diabetes impacts your circulation and your nerves. High blood sugar causes arteries to harden reducing blood flow. Less blood means less nutrients and oxygen, and your feet are already one of the worst parts of your body for circulation. Nerve damage due to blood sugar fluctuations means your body can’t feel damage, which reduces your natural healing response.
End result is a double whammy of poor healing response and a lack of nutrients and oxygen, which, if severe enough, leads to gangrene and amputation.
Sugar damages microvasculature. Lots of them in the feet. Feet are also far from the heart.
Type 1 here.
Many comments touch on it, but it is also a very complicated issue. Type 1 and Type 2 diabetes are very different diseases, but the side effects can be similar.
Even in well-controlled diabetes (either type), complications can occur. One of these is something called neuropathy. This is where a person has decreased nerve responses, which can lead to things like numbness and impotence.
If such an individual gets a blister or wound on their foot, if left untreated, it could get really bad, but this is true for anyone. But the person with neuropathy doesn’t have the same pain feedback so is less likely to notice, which could lead to a much worse infection by the time it is found.
Add to that that feet are slow to heal as they have decreased blood flow as they are the most distal (far from the body). Constant use also makes tissue repair slower.
Pain is there to help people from using injured parts. Without that feedback, it’s easier to hurt yourself.
Adding to this is that those with uncontrolled diabetes (either type) are more likely to have things called comorbidities, which are other issues which may not be related to the disease, but could make it harder to treat. Many type 2s tend to be overweight, but that may be due to an insulin resistance problem. Regardless, being overweight puts you at risk for high blood pressure as the body needs to compensate for moving all that extra blood by the heart pumping harder.
These are just a couple of examples. Trying to ELI5, but it is very complex.
Moral of the story is to try and take care of yourself and do regular body checks, including your feet, and try not to go outside without proper shoes on.
I certainly feel for type 2s. Imagine living your whole life a certain way and then being told to completely change your lifestyle. It’s hard to change, more so as you get older. Type 1 sucks a lot, but at least I got it young enough (reminder that even adults can get type 1 though) to not be completely set in my ways. My 90+ grandmother just got diagnosed with type 2 and she’s certainly taken an “eff it” approach. I can’t say i blame her at that age. I don’t want her to suffer, but I also understand that we both know it’s the end game and she’s got to enjoy what time she has left. Chances are she won’t live long enough to suffer the long term complications. But me? I’ve got many decades until I reach the “eff it” stage and as a type 1, those complications can come much faster.
The legs and feet have poorer circulation especially for the obese who tend towards diabetes. Poor circulation, high sugar, high insulin all contribute to destroying capillaries and the big toe often gets the worst of this.
I did my PhD on diabetic neuropathy.
The elevated sugar level damages nerves, starting with the longest ones first; those in your feet and hands.
The needles & pins sensation diabetics experience is their nerves whithering and dying.
As the nerves decay they impact the immune system so any cuts/lesions are slow to heal & this can cause gangrene.
diabetes causes poor circulation in tiny blood vessels as well as decreased sensation. the feet happen to be an area that has lots of very tiny arteries, naturally mediocre circulation, and aren’t an area of the body people give much attention to begin with.
so issues are more likely to occur and less likely to be noticed.
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