Diabetes now affects nearly 26 million Americans of all ages and 79 million people have what doctors call "pre-diabetes," according to 2011 estimates by the US Centers for Disease Control and Prevention.
Pre-diabetes, which the CDC says affects 35% of adults, is a condition where blood sugar levels are higher than normal but not yet high enough to be diagnosed as diabetes. Pre-diabetes greatly boosts a person's odds for type 2 diabetes, heart disease and stroke.
The vast majority of cases of diabetes are type 2, which develops when the body's cells gradually lose sensitivity to insulin.
According to experts, there's one very big reason for type 2 diabetes' continuing rise among Americans - weight gain.
"The percentage of US adults who are overweight or obese has also risen dramatically, and there is no doubt that rising rates of obesity are linked to the rising rates of diabetes," said Dr Christine Resta, an expert on diabetes in the division of endocrinology at Maimonides Medical Center in New York City.
But changes in the way doctors diagnose the illness may have played a role in rising numbers, too, another expert said.
Diabetes in America on the increase
"One of the reasons the incidence of diabetes has been increasing in the last few years is because the American Diabetes Association lowered the guidelines for diabetes diagnosis," explained Dr Jacob Warman, chief of endocrinology at The Brooklyn Hospital Center in New York City.
"Last year, the ADA recommended using [hemoglobin] A1c levels to diagnose both diabetes and pre-diabetes. This change in criteria resulted in a great increase of the number of patients with this diagnosis. The decision to change the criteria remains controversial, but the guidelines to increase exercise and decrease carbohydrate intake are valid."
In their report, the CDC agreed that the switch to hemoglobin A1c testing - which measures levels of blood glucose (sugar) over a period of two to three months - could help account for at least some of the rising numbers.
But the CDC's National Diabetes Fact Sheet for 2011 also notes that about 27% of Americans with diabetes, or about 7 million people, still do not know they have the disease. Among the other data included in the fact sheet:
About 1.9 million American adults were diagnosed with diabetes in 2010.
Diabetes rates continue to soar among racial and ethnic minorities.
Half of Americans aged 65 and older have pre-diabetes and nearly 27% have full-blown diabetes.
Around 215,000 Americans younger than age 20 have diabetes, including type 1 diabetes.
The 2011 diabetes incidence estimates mark a continued rise. In 2008, for example, the CDC estimated that 23.6 million Americans (7.8%) had diabetes and 57 million adults had pre-diabetes.
Diabetes and obesity
Besides the obesity epidemic and the switch to A1c-based diagnosis, the agency said that improvements in diabetes management may mean that many people with the disease are living longer, raising the total number affected.
Still, "these distressing numbers show how important it is to prevent type 2 diabetes and to help those who have diabetes manage the disease to prevent serious complications such as kidney failure and blindness," Ann Albright, director of CDC's Division of Diabetes Translation, said.
"We know that a structured lifestyle programme that includes losing weight and increasing physical activity can prevent or delay type 2 diabetes," she added.
Diabetes is the seventh leading cause of death in the United States and now costs $174 billion a year, including $116 billion in direct medical expenses, according to the CDC. People with diabetes are at increased risk for heart attack, stroke, high blood pressure, kidney failure, blindness and amputation of feet and legs.
If current trends continue, as many as one in three American adults could have diabetes by 2050, predicted a CDC study published last year.
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