The pain shot across the tops of Michael Jackson's feet as if someone was pounding him with a sledgehammer, sometimes becoming so unbearable he couldn't sleep.
The aerospace engineer blamed it on arthritis until his primary care physician ruled that out. Tests for Lupus and Lou Gherig's disease also came back negative. Finally, a doctor cut a small sample of skin from one of Jackson's feet and counted the nerve fibers under a microscope.
Jackson suffered from significant nerve damage stemming from prediabetes — a condition in which people have high blood glucose levels but not enough to be classified as diabetes.
Doctors have known for a while that those with prediabetes can experience mild weakness, numbness and pain from nerve damage, but a new Johns Hopkins study suggests that so-called neuropathy is much more significant than once thought. Like Jackson, patients can experience excruciating pain more typically associated with full-blown diabetes. About 50 percent of people with diabetes have neuropathy, according to the National Institute of Neurological Disorders and Stroke.
The numbness associated with neuropathy can contribute to some diabetics' eventual need for amputation. Diabetics tend to have poor blood circulation, which can lead to infection and ulcers. A patient may not notice an injury or infection due to lack of feeling, leading to amputation.
The Johns Hopkins researchers say their findings provide evidence that patients should be screened for prediabetes and neuropathy much earlier than once thought. The medical community also needs to do a better job at treating and diagnosing those with prediabetes, the researchers concluded. An estimated one in three Americans — 86 million people — have prediabetes, according to the U.S. Centers for Disease Control, and may be at particular risk to the unknown consequences of the disease.
"It means that even mild blood sugar elevations are important and it's important for us to be aggressive in how we treat that," said Dr. Michael Polydefkis, the study's senior author and a professor of neurology at the Johns Hopkins University School of Medicine and director of the Cutaneous Nerve Lab.
The Hopkins study is different from those done in the past because it showed deterioration over the entire length of sensory nerve fibers and not just at the ends, which suggests the damage is not localized.
The patients with prediabetes, studied over a period of three years, continued to have worsening damage to their small nerve fibers throughout the study just as patients with full-blown diabetes did. Skin samples taken from the ankle, thigh and knee showed a 10 percent loss in the density of nerve cells by the end of the study.
"I expected that people with diabetes would do worse, but I didn't really expect people with prediabetes to experience a similar rate of degradation of their small nerve fibers," Polydefkis said.
The results come as medical providers already are trying to better diagnose prediabetes.
For the last few years, the American Medical Association has worked to increase public awareness about prediabetes and get more phyisicians to screen at-risk patients. Working with the U.S. Centers for Disease Control, the association is offering doctors more information about prevention programs for their patients.
The medical association also is participating in a public service campaign to raise awareness of prediabetes as a serious health problem. The campaign encourages people to find out if they have prediabetes and to take steps to reverse their condition to avoid developing full diabetes.
If caught early, prediabetes can be treated with lifestyle changes, such as weight loss, exercise and diet modification to bring blood sugar levels down. Some doctors also believe the medicine used to treat diabetes could be used for prediabetes as well.
Untreated prediabetes could progress to diabetes and lead to lifelong health problems, including cardiovascular disease and skin problems. Diabetes can destroy the blood vessels of the retina leading to blindness and damage the kidneys, which the body uses to filter out waste, leading some patients to need dialysis treatment to survive. Research shows that 15 percent to 30 percent of overweight people with prediabetes will develop type 2 diabetes within five years unless they make lifestyle changes.
"We know that people who take preventive measures early on can slow the rate of decline," said Dr. Ruth S. Horowitz, chief of the division of endocrinology and metabolism at Greater Baltimore Medical Center.
There are some limits to the study. The sample size was small with 62 people, including 16 who were prediabetic and 52 with tingling and pain in their hands and feet.
Still, the Hopkins research could help convince insurance companies to eventually cover the treatment of prediabetes, some doctors said. Insurance companies don't always cover nutritional education and supplies for glucose testing until a patient has full-blown diabetes.
"This study reinforces the need for us to address prediabetes as an even more serious problem," said Stephen N. Davis, chair of the department of medicine at the University of Maryland School of Medicine. "It really does show there are consequences with prediabetes."
Jackson continues to cope with the consequences of his neuropathy. His nerve damage has gotten worse over time. He has lost much of the feeling in his feet and once dropped a cinder block on his foot without knowing until he looked down. His balance is off and he sometimes finds himself falling over in the shower. He is trying to manage the condition with medications and eating better.
"As a kid I ate a lot of candy," he said. "I was drowning myself with sugar as a kid, but back in the day nobody said much about sugar. I have tried to cut back now and it has helped."