Importance Previous studies have shown increasing prevalence of diabetes in the United States. New US data are available to estimate prevalence of and trends in diabetes. 
 
 Objective To estimate the recent prevalence and update US trends in total diabetes, diagnosed diabetes, and undiagnosed diabetes using National Health and Nutrition Examination Survey (NHANES) data. 
 
 Design, Setting, and Participants Cross-sectional surveys conducted between 1988-1994 and 1999-2012 of nationally representative samples of the civilian, noninstitutionalized US population; 2781 adults from 2011-2012 were used to estimate recent prevalence and an additional 23 634 adults from 1988-2010 were used to estimate trends. 
 
 Main Outcomes and Measures The prevalence of diabetes was defined using a previous diagnosis of diabetes or, if diabetes was not previously diagnosed, by (1) a hemoglobin A 1c level of 6.5% or greater or a fasting plasma glucose (FPG) level of 126 mg/dL or greater (hemoglobin A 1c or FPG definition) or (2) additionally including 2-hour plasma glucose (2-hour PG) level of 200 mg/dL or greater (hemoglobin A 1c , FPG, or 2-hour PG definition). Prediabetes was defined as a hemoglobin A 1c level of 5.7% to 6.4%, an FPG level of 100 mg/dL to 125 mg/dL, or a 2-hour PG level of 140 mg/dL to 199 mg/dL. 
 
 Results In the overall 2011-2012 population, the unadjusted prevalence (using the hemoglobin A 1c , FPG, or 2-hour PG definitions for diabetes and prediabetes) was 14.3% (95% CI, 12.2%-16.8%) for total diabetes, 9.1% (95% CI, 7.8%-10.6%) for diagnosed diabetes, 5.2% (95% CI, 4.0%-6.9%) for undiagnosed diabetes, and 38.0% (95% CI, 34.7%-41.3%) for prediabetes; among those with diabetes, 36.4% (95% CI, 30.5%-42.7%) were undiagnosed. The unadjusted prevalence of total diabetes (using the hemoglobin A 1c or FPG definition) was 12.3% (95% CI, 10.8%-14.1%); among those with diabetes, 25.2% (95% CI, 21.1%-29.8%) were undiagnosed. Compared with non-Hispanic white participants (11.3% [95% CI, 9.0%-14.1%]), the age-standardized prevalence of total diabetes (using the hemoglobin A 1c , FPG, or 2-hour PG definition) was higher among non-Hispanic black participants (21.8% [95% CI, 17.7%-26.7%]; P < .001), non-Hispanic Asian participants (20.6% [95% CI, 15.0%-27.6%]; P = .007), and Hispanic participants (22.6% [95% CI, 18.4%-27.5%]; P < .001). The age-standardized percentage of cases that were undiagnosed was higher among non-Hispanic Asian participants (50.9% [95% CI, 38.3%-63.4%]; P = .004) and Hispanic participants (49.0% [95% CI, 40.8%-57.2%]; P = .02) than all other racial/ethnic groups. The age-standardized prevalence of total diabetes (using the hemoglobin A 1c or FPG definition) increased from 9.8% (95% CI, 8.9%-10.6%) in 1988-1994 to 10.8% (95% CI, 9.5%-12.0%) in 2001-2002 to 12.4% (95% CI, 10.8%-14.2%) in 2011-2012 (P < .001 for trend) and increased significantly in every age group, in both sexes, in every racial/ethnic group, by all education levels, and in all poverty income ratio tertiles. 
 
 Conclusions and Relevance In 2011-2012, the estimated prevalence of diabetes was 12% to 14% among US adults, depending on the criteria used, with a higher prevalence among participants who were non-Hispanic black, non-Hispanic Asian, and Hispanic. Between 1988-1994 and 2011-2012, the prevalence of diabetes increased in the overall population and in all subgroups evaluated. ||||| About half of American adults have either diabetes or prediabetes, a new study says. 
 
 In 2011 to 2012, more than 12 percent of U.S. adults had diabetes, and 38 percent had prediabetes, a condition in which blood sugar levels are abnormally high, the study found. 
 
 In addition, more than one-third of people with diabetes were undiagnosed, meaning they didn't know they had the condition. The percentage of people with undiagnosed diabetes was particularly high among Asian Americans — about 50 percent of Asian Americans with diabetes were not aware they had the condition, according to the study. 
 
 "By learning more about who has diabetes — and who has the disease but does not know it — we can better target research and prevention efforts," Dr. Griffin Rodgers, director of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), said in a statement. "We have treatments to help people with diabetes, but treatments can only help those who have been diagnosed." [5 Diets That Fight Diseases] 
 
 Diabetes is a major cause of death in the United States, the researchers said. The condition also increases people's risk of heart disease and stroke and, if left untreated, can cause complications including nerve damage, kidney failure and blindness. Most cases of diabetes are type 2, in which the body's cells stop responding to the hormone insulin, which results in a buildup of sugar in the bloodstream. 
 
 In the new study, the researchers analyzed information from more than 26,000 U.S. adults who took part in surveys between 1988 and 2012. Participants were asked whether they had ever been diagnosed with diabetes, and they also gave blood samples so that the researchers could check the participants' blood sugar levels. 
 
 During the study period, the percentage of people with diabetes increased from less than 10 percent in the 1988-1994 period, to more than 12 percent in 2011-2012. This rise in diabetes parallels an increase in obesity — the most important risk factor for type 2 diabetes, the researchers said. 
 
 However, the prevalence of diabetes changed little between 2007 and 2012, which may reflect a leveling of obesity rates that occurred around the same time, the researchers noted. 
 
 Diabetes was most common among older adults — about one in three adults age 65 and over had the condition in 2011-2012, compared to 17 percent of adults ages 45 to 64, and 5 percent of adults younger than 45. 
 
 About one-third of whites with diabetes (32 percent) did not know they had the condition, compared to 37 percent of blacks, 49 percent of Hispanics and 51 percent of Asian Americans. 
 
 One reason for the high percentage of undiagnosed diabetes among Asian Americans may be that people in this ethnic group often develop type 2 diabetes at a lower body mass index (BMI) than people of other ethnic groups. This means that doctors may not screen Asian Americans for diabetes when, in fact, they could be at risk for the disease, the researchers said. 
 
 "The large proportion of people with undiagnosed diabetes points to both a greater need to test for type 2 diabetes and a need for more education on when to test for type 2 diabetes, especially since populations such as Asian Americans may develop type 2 at a lower body mass than other groups," study co-author Catherine Cowie, director of diabetes epidemiology programs at NIDDK, said in a statement. 
 
 The researchers hope that future studies will provide more information about which subgroups of people are at highest risk for underdiagnoses. 
 
 The researchers noted that the American Diabetes Association recommends that people have two tests to confirm a diagnosis of diabetes. But in the new study, the researchers often had information from just one blood test. This means that some participants may have been classified as having diabetes when they didn't have the condition, the researchers said. 
 
 The study is published in the Sept. 8 issue of the Journal of the American Medical Association. 
 
 Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science. ||||| More than half of Asian Americans with diabetes are undiagnosed 
 
 New statistics also show rising prevalence of diabetes among all groups 
 
 More than half of Asian Americans and nearly half of Hispanic Americans with diabetes are undiagnosed, according to researchers from the National Institutes of Health and the Centers for Disease Control and Prevention. Their results were published Sept. 8 in JAMA, the Journal of the American Medical Association . 
 
 Additionally, prevalence of diabetes for all American adults went up, from nearly 10 percent to over 12 percent between 1988 and 2012. Diabetes prevalence – how common the condition is – also went up in every age, sex, level of education, income and racial/ethnic subgroup. One bright spot: The proportion of people with diabetes that was undiagnosed decreased 23 percent between 1988-1994 and 2011-2012. The statistics account for age differences across the surveys. 
 
 Using newly available 2011-2012 data from the CDC’s National Health and Nutrition Examination Survey (NHANES), researchers were able to quantify diabetes prevalence for Asian Americans for the first time and found that they have the highest proportion of diabetes that was undiagnosed among all ethnic and racial subgroups studied, at 51 percent. Diabetes was also common in Asian Americans, at 21 percent. Hispanic Americans had the highest prevalence of diabetes at nearly 23 percent, with 49 percent of that undiagnosed. 
 
 One difference between Asian Americans and the other groups studied, however, is that Asian Americans often develop type 2 diabetes at a lower body mass index (BMI). The NHANES data showed the average BMI for all Asian Americans surveyed was under 25. For the U.S. population overall, the average BMI was just below 29. A BMI of 25 to under 30 is considered overweight, and a BMI of 30 or greater is considered obese. The American Diabetes Association recommends Asian Americans get tested for diabetes at a BMI of 23 or higher, a lower BMI threshold than the general population. 
 
 “The large proportion of people with undiagnosed diabetes points to both a greater need to test for type 2 diabetes and a need for more education on when to test for type 2 diabetes, especially since populations such as Asian Americans may develop type 2 at a lower body mass than other groups,” said the study’s senior author, Catherine Cowie, Ph.D., director of diabetes epidemiology programs at the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). 
 
 Researchers used NHANES results from 26,415 adults between 1988 and 2012. For the 2011-2012 survey, NHANES surveyed a disproportionate number of Asian Americans. 
 
 “By NHANES surveying a much larger group of Asian Americans to provide more precise statistics, we’re able to identify with hard data a problem that had not been well-studied in the past,” said first author Andy Menke, Ph.D., an NIDDK contractor. “However, the Asian population is diverse, and we do not yet have data on differences within that population. Getting more specific data on Asian and other subgroups may help better pinpoint education and diagnosis efforts.” 
 
 About 1 in 5 non-Hispanic black adults had diabetes, higher than the overall population. However, they had a lower proportion of diabetes that was undiagnosed than the Asian or Hispanic subgroups, with about 37 percent being undiagnosed. Non-Hispanic whites had the lowest prevalence of diabetes at 11 percent, and they had the lowest proportion of undiagnosed, at just over 32 percent. 
 
 In type 1 diabetes, the body does not make insulin. In type 2 diabetes — the most common type, which has increased along with the obesity epidemic — the body does not make or use insulin well. Both types of diabetes have potential complications including heart, kidney, nerve and eye diseases. 
 
 “By learning more about who has diabetes – and who has the disease but does not know it – we can better target research and prevention efforts,” said NIDDK Director Griffin P. Rodgers, M.D. “We have treatments to help people with diabetes, but treatments can only help those who have been diagnosed. I hope our research can serve as a reminder for people at risk for diabetes to get screened for this potentially devastating disease.” 
 
 NIDDK provides free diabetes-related information and education resources at http://www.diabetes.niddk.nih.gov and through the National Diabetes Education Program, a partnership between NIH and the CDC, at http://www.ndep.nih.gov. 
 
 This study was conducted by the NIDDK, with contractors from Social and Scientific Systems, Inc., supported under NIDDK contract GS10F0381L and by the CDC. This study supports the Healthy People 2020 goal of increasing the diagnosis of diabetes among those with the disease. 
 
 The NIDDK, a component of the NIH, conducts and supports research on diabetes and other endocrine and metabolic diseases; digestive diseases, nutrition and obesity; and kidney, urologic and hematologic diseases. Spanning the full spectrum of medicine and afflicting people of all ages and ethnic groups, these diseases encompass some of the most common, severe and disabling conditions affecting Americans. For more information about the NIDDK and its programs, see http://www.niddk.nih.gov. 
 
 About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov. 
 
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– More than half of all adult Americans have diabetes or prediabetes—a condition marked by abnormally high blood sugar levels—according to a study published today in the Journal of the American Medical Association. Live Science reports survey results between 2011 and 2012 showed more than 12% of US residents over the age of 18 had diabetes—that's up from less than 10% in 1988—and another 38% had prediabetes. The numbers are worst for Americans over 65, a full one-third of whom have diabetes. Perhaps even more alarming, more than one-third of US adults with the disease—which can cause blindness, heart disease, kidney failure, and death—don't know they have it. More than half of Asian Americans and nearly half of Hispanic Americans with diabetes are undiagnosed, according to a press release from the National Institutes of Health. Live Science reports Asian Americans may have so many cases of undiagnosed diabetes because they develop it at a lower BMI than other ethnic groups, which means doctors may not be screening Asian Americans who have the disease but don't appear obese. “By learning more about who has diabetes—and who has the disease but does not know it—we can better target research and prevention efforts,” says the director of the National Institute of Diabetes and Digestive and Kidney Diseases in the press release. “We have treatments to help people with diabetes, but treatments can only help those who have been diagnosed."