Objective: To evaluate the prevalence and time trends for diagnosed and undiagnosed diabetes, impaired fasting glucose, and impaired glucose tolerance in U.S. adults by age, sex, and race or ethnic group, based on data from the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III) and prior Health and Nutrition Examination Surveys (HANESs).
Research design and methods: NHANES III contained a probability sample of 18,825 U.S. adults > or = 20 years of age who were interviewed to ascertain a medical history of diagnosed diabetes, a subsample of 6,587 adults for whom fasting plasma glucose values were obtained, and a subsample of 2,844 adults between 40 and 74 years of age who received an oral glucose tolerance test. The Second National Health and Nutrition Examination Survey, 1976-1980, and Hispanic HANES used similar procedures to ascertain diabetes. Prevalence was calculated using the 1997 American Diabetes Association fasting plasma glucose criteria and the 1980-1985 World Health Organization (WHO) oral glucose tolerance test criteria.
Results: Prevalence of diagnosed diabetes in 1988-1994 was estimated to be 5.1% for U.S. adults > or = 20 years of age (10.2 million people when extrapolated to the 1997 U.S. population). Using American Diabetes Association criteria, the prevalence of undiagnosed diabetes (fasting plasma glucose > or = 126 mg/dl) was 2.7% (5.4 million), and the prevalence of impaired fasting glucose (110 to < 126 mg/dl) was 6.9% (13.4 million). There were similar rates of diabetes for men and women, but the rates for non-Hispanic blacks and Mexican-Americans were 1.6 and 1.9 times the rate for non-Hispanic whites. Based on American Diabetes Association criteria, prevalence of diabetes (diagnosed plus undiagnosed) in the total population of people who were 40-74 years of age increased from 8.9% in the period 1976-1980 to 12.3% by 1988-1994. A similar increase was found when WHO criteria were applied (11.4 and 14.3%).
Conclusions: The high rates of abnormal fasting and postchallenge glucose found in NHANES III, together with the increasing frequency of obesity and sedentary lifestyles in the population, make it likely that diabetes will continue to be a major health problem in the U.S.