This is a Reuters Health News summary from terrific work from Dave Margolis and coworkers.
About 26 million Americans have diabetes, and an estimated 65,000 had a lower limb amputation in 2006, the most recent year with available data.
One recent study found that the rate of amputation may be declining among Americans with diabetes. But the new findings, reported in the journal Diabetes Care, suggest that in some parts of the country that rate can be almost double the national average — at least among older Americans.
Amputation is a complication of diabetes because the disease often causes nerve damage over time. When people lose sensation in their feet and legs, they may more easily get a cut, blister or sore — even from ill-fitting shoes — and be less likely to notice it until it's infected.
Those wounds can be difficult to heal because diabetes often causes poor blood circulation to the lower limbs. In severe cases, doctors may choose to amputate a foot or leg to prevent a dangerous, systemic infection.
The current study found that in 2008, certain pockets of Arkansas, Louisiana, Mississippi, Oklahoma and Texas had the highest rates of diabetes-related amputation among Medicare beneficiaries — at about 7 to 8 per 1,000.
That compared with a national rate of 4.5 per 1,000 in the same year. And certain locations — like portions of Arizona, Florida, Michigan and New Mexico — had particularly low rates. There, older adults with diabetes had amputations at a rate of 2.4 to 3.5 per 1,000.
“The rate of amputation really varies greatly,” said lead researcher Dr. David J. Margolis, of the University of Pennsylvania in Philadelphia. “We don't know why that is, we just know that it's there.”
The researchers were able to account for some factors — like the prevalence of diabetes in a given area, the number of people diagnosed with diabetic foot ulcers, and an area's income and racial mix. That explained some of the geographical variation, Margolis told Reuters Health, but not all of it.
He cautioned that the relatively high rates of amputation in certain regions do not necessarily mean the rates are “too high.” It's possible, for example, that doctors in those areas see more people with severe diabetes complications and based on experience, have found that an earlier amputation is often better.
“We don't know that they are doing 'too many,'” Margolis said. “For all we know, they could be doing the right amount.”
There are no general guidelines on when to do an amputation in someone with severe diabetic ulcers, so it's up to the doctor's judgment and what the patient wants.
“It's not a clear-cut decision,” Margolis noted.
The findings are based on data from Medicare, the government insurance program for older Americans, for the years 2006 to 2008. About 5 million beneficiaries had diabetes each of those years.
It's not known whether the same geographical variations in amputation would be true of younger Americans with diabetes, the researchers say.
More research is now needed to understand the reasons for the variations among Medicare beneficiaries, Margolis said. For now, people with diabetes can take steps to protect their limbs, he noted.
Experts recommend that people with diabetes check their feet everyday to catch cuts, swelling or other injuries early. They should also have their doctor examine their feet at least once a year.
Diabetic nerve damage often causes pain at first, Margolis said. So if you have pain, tell your doctor and talk about what you should do to protect your feet and legs.
Nerve damage can also change the shape of the feet, Margolis pointed out. In some cases, your doctor might recommend special therapeutic shoes, so you are not trying to wedge your changed feet into regular shoes.