Diabetics are often warned about the devastating potential of wounds on the feet to cause threat to life and limb by becoming gangrenous. Diabetics aren't often warned that hot, swollen, aching feet without breaks in the skin can also pose a serious health problem. The medical term for the condition is Charcot neuroarthopathy.
A typical story of Charcot neuroarthropathy runs something like this: Sarah was 50-something type 2 diabetic who was health-conscious, but just never took her blood sugar levels. She felt diet and exercise really ought to be enough.
One day Sarah noticed a sharp pain in her right foot while jogging. There was no break in the skin, and no sign of infection. She thought she might have run across a rock and injured a muscle somehow, so she did not give her condition much thought.
The next day this health-minded type 2 diabetic didn't feel well at all. She had a slight fever, and her pulse was racing. When she got to the urgent care clinic, her normally healthy blood pressure had gone up to 170/110, and she was running about 2° F/1° C of fever. There were still no signs of infection, but her foot was red, hard, and swollen even past her ankles, and there were tiny bruises forming on it top and bottom. The swelling and seemed concentrated, however, in the midsection of her foot, moving forward toward the toes and upward toward the knees, symmetrically across the foot.
The doctor ruled out cellulitis (strep infection of the skin), abscesses, arterial blockages, blood clots, and gout. (Before the twenty-first century, doctors would have also ruled out leprosy and polio.) Because the swelling was all across the foot rather than on just one side of the foot, and because it was in the middle of the foot rather than at the toes or the ankles, the doctor was also able to rule out arterial blockages. And when Sarah mentioned that she was a diabetic, and the doctor noticed that her blood sugar level was 310 mg/dl, the it was realized that all the signs pointed to Charcot neuroarthropathy.
This is a condition that sneaks up on type 2 diabetics who don't keep their blood sugar levels in good control. There may be changes in the foot for months before there is pain. Unlike other causes of foot pain, gout, for instance, Charcot neuroarthropathy does not get better. The pain just gets worse and worse until it is treated.
In this condition, bones in the foot very literally dissolve--without causing pain. It's only when the remaining bone starts to rebuild itself that pain can be really intense, usually after some minor bump, thump, or bruise to the foot that ordinarily would not even be noticed.
For any treatment of this condition to work long-term, there has to be good blood sugar control. If it is caught soon enough, sometimes just keeping weight off the affected foot for a few weeks allows it to heal. Then the condition is treated in the same way as osteoporosis. Surgery is usually only performed when the bones have grown back in such a way that shoes don't fit or there is a problem with bunions.
Every year about 1 in 50 type 2 diabetics who do not monitor their blood sugars find out in a very painful way that diabetes can even affect the bones, as well as nerves, in the feet. If you have a sudden onset of foot pain that just won't go away, be sure to stop any exercise that involves putting a load on your feet, and see your doctor right away.
, Taylor R. Charcot neuroarthropathy: An often overlooked complication of diabetes. Cleve Clin J Med. 2010 Sep;77(9):593-9. Anderson MA