Yiling J. Cheng

Prevalence of Diabetic Retinopathy in the United States, 2005-2008

CONTEXT The prevalence of diabetes in the United States has increased. People with diabetes are at risk for diabetic retinopathy. No recent national population-based estimate of the prevalence and severity of diabetic retinopathy exists. OBJECTIVES To describe the prevalence and risk factors of diabetic retinopathy among US adults with diabetes aged 40 years and older. DESIGN, SETTING, AND PARTICIPANTS Analysis of a cross-sectional, nationally representative sample of the National Health and Nutrition Examination Survey 2005-2008 (N = 1006). Diabetes was defined as a self-report of a previous diagnosis of the disease (excluding gestational diabetes mellitus) or glycated hemoglobin A(1c) of 6.5% or greater. Two fundus photographs were taken of each eye with a digital nonmydriatic camera and were graded using the Airlie House classification scheme and the Early Treatment Diabetic Retinopathy Study severity scale. Prevalence estimates were weighted to represent the civilian, noninstitutionalized US population aged 40 years and older. MAIN OUTCOME MEASUREMENTS Diabetic retinopathy and vision-threatening diabetic retinopathy. RESULTS The estimated prevalence of diabetic retinopathy and vision-threatening diabetic retinopathy was 28.5% (95% confidence interval [CI], 24.9%-32.5%) and 4.4% (95% CI, 3.5%-5.7%) among US adults with diabetes, respectively. Diabetic retinopathy was slightly more prevalent among men than women with diabetes (31.6%; 95% CI, 26.8%-36.8%; vs 25.7%; 95% CI, 21.7%-30.1%; P = .04). Non-Hispanic black individuals had a higher crude prevalence than non-Hispanic white individuals of diabetic retinopathy (38.8%; 95% CI, 31.9%-46.1%; vs 26.4%; 95% CI, 21.4%-32.2%; P = .01) and vision-threatening diabetic retinopathy (9.3%; 95% CI, 5.9%-14.4%; vs 3.2%; 95% CI, 2.0%-5.1%; P = .01). Male sex was independently associated with the presence of diabetic retinopathy (odds ratio [OR], 2.07; 95% CI, 1.39-3.10), as well as higher hemoglobin A(1c) level (OR, 1.45; 95% CI, 1.20-1.75), longer duration of diabetes (OR, 1.06 per year duration; 95% CI, 1.03-1.10), insulin use (OR, 3.23; 95% CI, 1.99-5.26), and higher systolic blood pressure (OR, 1.03 per mm Hg; 95% CI, 1.02-1.03). CONCLUSION In a nationally representative sample of US adults with diabetes aged 40 years and older, the prevalence of diabetic retinopathy and vision-threatening diabetic retinopathy was high, especially among Non-Hispanic black individuals.

Mortality Trends in Men and Women with Diabetes, 1971 to 2000

Context Whether the mortality reductions observed over recent decades in the United States have been similar among diabetic and nondiabetic persons is unknown. Contribution The 19712000 National Health and Nutrition Examination Surveys and vital statistics data reveal higher mortality in the diabetic population than in the nondiabetic population. Over this period, diabetic men experienced mortality reductions that paralleled those of nondiabetic men. However, mortality rates in women have not changed, and the mortality difference between diabetic and nondiabetic women more than doubled. Implications Mortality among diabetic women does not reflect improvements in the care of diabetes and other cardiovascular risk factors. Understanding the sex differences in diabetes outcomes should be a research priority. The Editors The decrease in cardiovascular disease (CVD) mortality rates and the accompanying increases in overall longevity are major public health successes in the United States over the past 40 years (1). These have been attributed to decreases in CVD risk factors, as well as advances in medical management and revascularization, among persons with diagnosed CVD (2, 3). Aggressive management of CVD risk factors has been shown to be particularly effective among persons with diabetes, and implementation of these findings into practice along with aggressive diabetes care should, in theory, result in increased longevity among persons with diabetes (49). The quality of diabetes care and levels of certain CVD risk factors have improved among the U.S. population with diagnosed diabetes (10, 11). Whether reductions in mortality have occurred among persons with diabetes, however, remains unclear. Although regional studies of persons with diabetes suggest that rates of all-cause mortality and cardiovascular complications have declined in recent decades (1215), the only nationally representative study to examine trends in mortality rates of adults with diabetes found no improvement between 1971 and 1992 (16). However, no national studies of mortality trends of the U.S. diabetic population have extended through the 1990s, a period of major advances in clinical diabetes management, leaving the question of whether longevity in this population has improved (4, 11, 17). Thus, we assembled data from 3 consecutive nationally representative cohorts to assess whether all-cause and CVD mortality have declined among the U.S. population with diabetes and whether the disparity in mortality rates between persons with and without diabetes has decreased. Methods Study Design and Population The National Health and Nutrition Examination Survey (NHANES) is a series of independent, nationally representative health surveys of the U.S. noninstitutionalized population conducted from 1971 to 1975 (NHANES I), 1976 to 1980 (NHANES II), and 1988 to 1994 (NHANES III) (1820). Each survey used a stratified, multistage probability design that sampled, interviewed, and examined participants to determine their health status. Sampling approaches, interview, and examination methods were standardized across surveys, and data were linked to death certificate data (21). To minimize bias from differential follow-up, we limited follow-up to 12.2 years, which was the maximum period for the survey with the shortest follow-up (NHANES III). Thus, the follow-up years for the 3 survey cohorts were 1971 to 1986, 1976 to 1992, and 1988 to 2000. Overall, 28043 persons, 27801 persons, and 39695 persons were selected for NHANES I, II, and III, respectively, and 75% (20749 persons), 73% (20322 persons), and 78% (30818 persons) were examined. We restricted our analyses to adults age 35 to 74 years who were examined at baseline. These groups included 8654 (80%), 8213 (76%), and 9399 (90%) persons from each of the 3 cohorts. After excluding persons without information on diabetes (7, 3, and 12 persons) or death (176, 5, and 6 persons), we were left with 8471, 8205, and 9381 persons in the primary analyses. Previous analyses have indicated little bias due to nonresponse (22, 23). Measurements Demographic characteristics, self-reported diabetes status, duration of disease, insulin use, and history of CVD (heart attack, heart failure, or stroke) were determined by interview. Weight and height were measured and were used to calculate body mass index (BMI). Underlying causes of death were classified according to the International Classification of Diseases, Ninth Revision, with CVD coded as 390 to 448. Statistical Analysis We completed mortality rates as the number of deaths divided by the sum of person-years and standardized by age and sex to the 2000 U.S. population. We examined changes in absolute standardized mortality rates over time by using t tests. We also used proportional hazards models to estimate the hazard rate ratios for the NHANES II and III cohorts compared with the NHANES I cohort among the diabetic and nondiabetic populations, with primary models controlling for age, sex, and race or ethnicity and additional models controlling for duration of diabetes and prevalent CVD. We also examined 2-way interactions of survey among persons with diabetes with each of the covariates mentioned above. We assessed the validity of the proportional hazards assumption by adding time-dependent variables to the model (that is, the interaction of age, sex, or race or ethnicity and the logarithm of follow-up duration). Because this assumption was not met across sex, we fit models separately by sex. Mortality rate estimation and proportional hazards regression incorporated survey weights such that results are representative of the U.S. noninstitutionalized population and account for the stratified, clustered design and the unequal probabilities of selection from oversampling and nonresponse (24). We combined data across the 3 surveys for regression analyses, using the original survey weights and design variables. We renumbered strata to appropriately represent their respective surveys, and we calculated degrees of freedom as the number of primary sampling units minus the number of strata. Because we used original survey weights (as opposed to constructing new weights for pooled analyses), these analyses make the assumption that each survey sample is drawn from a different population, as opposed to 3 surveys from a single underlying population (25). We conducted all statistical analyses by using SUDAAN, version 9.1 (RTI International, Research Triangle Park, North Carolina), which uses Taylor series linearization to estimate variances. Role of the Funding Source The U.S. Department of Health and Human Services is the funding source for NHANES and oversees the conduct and reporting of the NHANES surveys. Results Among both men and women with diabetes, the proportion of nonwhite persons roughly doubled across the survey years, the level of education increased substantially, and mean BMI increased (Table 1). In diabetic womenbut not diabetic menthe average age at diagnosis decreased statistically significantly (mean decrease, 2.9 years) across the 3 surveys, and the average age of the diabetic population decreased by 2.5 years, from 59.1 to 56.6 years. Almost all of the secular trends in race or ethnicity, education, and BMI observed in persons with diabetes also occurred in those without diabetes. Table 1. Characteristics of the U.S. Population Age 35 to 74 Years with and without Diagnosed Diabetes Between 1971 to 1986 and 1988 to 2000 in the overall nondiabetic population (both men and women), all-cause mortality rates decreased from 14.4 to 9.5 annual deaths per 1000 persons (P< 0.001) and CVD deaths decreased from 7.0 to 3.4 annual deaths per 1000 persons (P< 0.001) (Table 2). Among the overall diabetic population, the all-cause mortality rate did not statistically significantly change (30 annual deaths per 1000 persons in 1971 to 1986 vs. 25.2 annual deaths per 1000 persons in 1988 to 2000). For CVD mortality, the absolute difference in mortality among the diabetic population between 1971 to 1986 and 1988 to 2000 (18.2 vs. 11.1 annual deaths per 1000 persons) was greater than that of the nondiabetic population, but this decrease was not significant (P= 0.09). Table 2. Trends in Mortality Rates in the U.S. Population Age 35 to 74 Years, by Diabetes Status and Sex, 19712000 Findings in the overall population, however, obscured important sex-related differences, wherein mortality rates decreased among diabetic men but not among diabetic women (interaction between survey year and sex, P= 0.005 for all-cause mortality and P= 0.59 for CVD mortality) (Figure 1). All-cause mortality rates among diabetic men decreased by 43% (from 42.6 to 24.4 annual deaths per 1000 persons) between 1971 to 1986 and 1988 to 2000 (P= 0.03). In an analysis that controlled for age and race or ethnicity, the all-cause mortality rate ratio for diabetic men in 1988 to 2000 compared with 1971 to 1986 was 0.61 (95% CI, 0.43 to 0.86). Trends for the CVD mortality rate paralleled those of all-cause mortality (26.4 vs. 12.8 annual deaths per 1000 persons; P= 0.06 for difference) (Table 2 and Figure 2). In an analysis that controlled for age, sex, and race or ethnicity, the CVD mortality rate ratio for diabetic men in 1988 to 2000 compared with 1971 to 1986 was 0.62 (CI, 0.39 to 1.01) (Table 2 and Figure 2). Additional adjustment for diabetes duration, BMI, and prevalent CVD had no appreciable effect on the mortality rate ratios (data not shown). Figure 1. Age-adjusted all-cause mortality rates among the U.S. population age 35 to 74 years with and without diabetes, by cohort and sex. Figure 2. Age-adjusted cardiovascular disease mortality rates among the U.S. population age 35 to 74 years with and without diabetes, by cohort and sex. The absolute difference in all-cause mortality rates between men with and without diabetes was 23.6 annual deaths per 1000 persons (42.6 vs. 19.0 deaths) in 1971 to 1986 compared with 12.

Prevalence and Incidence Trends for Diagnosed Diabetes Among Adults Aged 20 to 79 Years, United States, 1980-2012

IMPORTANCE Although the prevalence and incidence of diabetes have increased in the United States in recent decades, no studies have systematically examined long-term, national trends in the prevalence and incidence of diagnosed diabetes. OBJECTIVE To examine long-term trends in the prevalence and incidence of diagnosed diabetes to determine whether there have been periods of acceleration or deceleration in rates. DESIGN, SETTING, AND PARTICIPANTS We analyzed 1980-2012 data for 664,969 adults aged 20 to 79 years from the National Health Interview Survey (NHIS) to estimate incidence and prevalence rates for the overall civilian, noninstitutionalized, US population and by demographic subgroups (age group, sex, race/ethnicity, and educational level). MAIN OUTCOMES AND MEASURES The annual percentage change (APC) in rates of the prevalence and incidence of diagnosed diabetes (type 1 and type 2 combined). RESULTS The APC for age-adjusted prevalence and incidence of diagnosed diabetes did not change significantly during the 1980s (for prevalence, 0.2% [95% CI, -0.9% to 1.4%], P = .69; for incidence, -0.1% [95% CI, -2.5% to 2.4%], P = .93), but each increased sharply during 1990-2008 (for prevalence, 4.5% [95% CI, 4.1% to 4.9%], P < .001; for incidence, 4.7% [95% CI, 3.8% to 5.6%], P < .001) before leveling off with no significant change during 2008-2012 (for prevalence, 0.6% [95% CI, -1.9% to 3.0%], P = .64; for incidence, -5.4% [95% CI, -11.3% to 0.9%], P = .09). The prevalence per 100 persons was 3.5 (95% CI, 3.2 to 3.9) in 1990, 7.9 (95% CI, 7.4 to 8.3) in 2008, and 8.3 (95% CI, 7.9 to 8.7) in 2012. The incidence per 1000 persons was 3.2 (95% CI, 2.2 to 4.1) in 1990, 8.8 (95% CI, 7.4 to 10.3) in 2008, and 7.1 (95% CI, 6.1 to 8.2) in 2012. Trends in many demographic subpopulations were similar to these overall trends. However, incidence rates among non-Hispanic black and Hispanic adults continued to increase (for interaction, P = .03 for non-Hispanic black adults and P = .01 for Hispanic adults) at rates significantly greater than for non-Hispanic white adults. In addition, the rate of increase in prevalence was higher for adults who had a high school education or less compared with those who had more than a high school education (for interaction, P = .006 for <high school and P < .001 for high school). CONCLUSIONS AND RELEVANCE Analyses of nationally representative data from 1980 to 2012 suggest a doubling of the incidence and prevalence of diabetes during 1990-2008, and a plateauing between 2008 and 2012. However, there appear to be continued increases in the prevalence or incidence of diabetes among subgroups, including non-Hispanic black and Hispanic subpopulations and those with a high school education or less.

Prevalence of impaired fasting glucose and its relationship with cardiovascular disease risk factors in US adolescents, 1999-2000.

Objective. PEDIATRICS (ISSN 0031 4005). Published in the public domain by the American Academy of Pediatrics.Several studies have reported increases in the occurrence of type 2 diabetes in youths. People with prediabetic states such as impaired fasting glucose (IFG) are at increased risk for developing diabetes and cardiovascular disease (CVD). The objective of this study was to examine the prevalence of IFG and its relationship with overweight and CVD risk factors in a nationally representative sample of US adolescents who were aged 12 to 19 years. Methods. We used data from the 1999–2000 National Health and Nutrition Examination Survey (NHANES). Adolescents who had fasted for 8 hours or more were included in the study (n = 915). IFG was defined as a fasting glucose of 100 to 125 mg/dL. Participants were classified as overweight when their age- and gender-specific BMI was ≥95th percentile and as at-risk for overweight when their BMI was ≥85th and <95th percentile. Results. In 1999–2000, the prevalence of IFG in US adolescents was 7.0% and was higher in boys than in girls (10.0% vs 4.0%). Prevalence of IFG was higher in overweight adolescents (17.8%) but was similar in those with normal weight and those who were at risk for overweight (5.4% vs 2.8%). The prevalence of IFG was significantly different across racial/ethnic groups (13.0%, 4.2%, and 7% in Mexican Americans, non-Hispanic black individuals, and non-Hispanic white individuals, respectively). Adolescents with IFG had significantly higher mean hemoglobin A1c, fasting insulin, total and low-density lipoprotein cholesterol, triglycerides, and systolic blood pressure and lower high-density lipoprotein cholesterol than those with normal fasting glucose concentrations. Conclusions. These data, representing 27 million US adolescents, reveal a very high prevalence of IFG (1 in 10 boys and 1 in 25 girls) among adolescents; the condition affects 1 in every 6 overweight adolescents. Adolescents with IFG have features of insulin resistance and worsened CVD risk factors. Evidence for prevention is still forthcoming in this age group.

Trends in lifetime risk and years of life lost due to diabetes in the USA, 1985-2011: a modelling study.

BACKGROUND Diabetes incidence has increased and mortality has decreased greatly in the USA, potentially leading to substantial changes in the lifetime risk of diabetes. We aimed to provide updated estimates for the lifetime risk of development of diabetes and to assess the effect of changes in incidence and mortality on lifetime risk and life-years lost to diabetes in the USA. METHODS We incorporated data about diabetes incidence from the National Health Interview Survey, and linked data about mortality from 1985 to 2011 for 598 216 adults, into a Markov chain model to estimate remaining lifetime diabetes risk, years spent with and without diagnosed diabetes, and life-years lost due to diabetes in three cohorts: 1985-89, 1990-99, and 2000-11. Diabetes was determined by self-report and was classified as any diabetes, excluding gestational diabetes. We used logistic regression to estimate the incidence of diabetes and Poisson regression to estimate mortality. FINDINGS On the basis of 2000-11 data, lifetime risk of diagnosed diabetes from age 20 years was 40·2% (95% CI 39·2-41·3) for men and 39·6% (38·6-40·5) for women, representing increases of 20 percentage points and 13 percentage points, respectively, since 1985-89. The highest lifetime risks were in Hispanic men and women, and non-Hispanic black women, for whom lifetime risk now exceeds 50%. The number of life-years lost to diabetes when diagnosed at age 40 years decreased from 7·7 years (95% CI 6·5-9·0) in 1990-99 to 5·8 years (4·6-7·1) in 2000-11 in men, and from 8·7 years (8·4-8·9) to 6·8 years (6·7-7·0) in women over the same period. Because of the increasing diabetes prevalence, the average number of years lost due to diabetes for the population as a whole increased by 46% in men and 44% in women. Years spent with diabetes increased by 156% in men and 70% in women. INTERPRETATION Continued increases in the incidence of diagnosed diabetes combined with declining mortality have led to an acceleration of lifetime risk and more years spent with diabetes, but fewer years lost to the disease for the average individual with diabetes. These findings mean that there will be a continued need for health services and extensive costs to manage the disease, and emphasise the need for effective interventions to reduce incidence. FUNDING None.

Secular Changes in U.S. Prediabetes Prevalence Defined by Hemoglobin A1c and Fasting Plasma Glucose: National Health and Nutrition Examination Surveys, 1999–2010

OBJECTIVE Using a nationally representative sample of the civilian noninstitutionalized U.S. population, we estimated prediabetes prevalence and its changes during 1999–2010. RESEARCH DESIGN AND METHODS Data were from 19,182 nonpregnant individuals aged ≥12 years who participated in the 1999–2010 National Health and Nutrition Examination Surveys. We defined prediabetes as hemoglobin A1c (A1C) 5.7 to <6.5% (39 to <48 mmol/mol, A1C5.7) or fasting plasma glucose (FPG) 100 to <126 mg/dL (impaired fasting glucose [IFG]). We estimated the prevalence of prediabetes, A1C5.7, and IFG for 1999–2002, 2003–2006, and 2007–2010. We calculated estimates age-standardized to the 2000 U.S. census population and used logistic regression to compute estimates adjusted for age, sex, race/ethnicity, poverty-to-income ratio, and BMI. Participants with self-reported diabetes, A1C ≥6.5% (≥48 mmol/mol), or FPG ≥126 mg/dL were included. RESULTS Among those aged ≥12 years, age-adjusted prediabetes prevalence increased from 27.4% (95% CI 25.1–29.7) in 1999–2002 to 34.1% (32.5–35.8) in 2007–2010. Among adults aged ≥18 years, the prevalence increased from 29.2% (26.8–31.8) to 36.2% (34.5–38.0). As single measures among individuals aged ≥12 years, A1C5.7 prevalence increased from 9.5% (8.4–10.8) to 17.8% (16.6–19.0), a relative increase of 87%, whereas IFG remained stable. These prevalence changes were similar among the total population, across subgroups, and after controlling for covariates. CONCLUSIONS During 1999–2010, U.S. prediabetes prevalence increased because of increases in A1C5.7. Continuous monitoring of prediabetes is needed to identify, quantify, and characterize the population of high-risk individuals targeted for ongoing diabetes primary prevention efforts.

Secular Changes in the Age-Specific Prevalence of Diabetes Among U.S. Adults 1988–2010

OBJECTIVE To examine the age-specific changes of prevalence of diabetes among U.S. adults during the past 2 decades. RESEARCH DESIGN AND METHODS This study included 22,586 adults sampled in three periods of the National Health and Nutrition Examination Survey (1988–1994, 1999–2004, and 2005–2010). Diabetes was defined as having self-reported diagnosed diabetes or having a fasting plasma glucose level ≥126 mg/dL or HbA1c ≥6.5% (48 mmol/mol). RESULTS The number of adults with diabetes increased by 75% from 1988–1994 to 2005–2010. After adjusting for sex, race/ethnicity, and education level, the prevalence of diabetes increased over the two decades across all age-groups. Younger adults (20–34 years of age) had the lowest absolute increase in diabetes prevalence of 1.0%, followed by middle-aged adults (35–64) at 2.7% and older adults (≥65) at 10.0% (all P < 0.001). Comparing 2005–2010 with 1988–1994, the adjusted prevalence ratios (PRs) by age-group were 2.3, 1.3, and 1.5 for younger, middle-aged, and older adults, respectively (all P < 0.05). After additional adjustment for body mass index (BMI), waist-to-height ratio (WHtR), or waist circumference (WC), the adjusted PR remained statistically significant only for adults ≥65 years of age. CONCLUSIONS During the past two decades, the prevalence of diabetes increased across all age-groups, but adults ≥65 years of age experienced the largest increase in absolute change. Obesity, as measured by BMI, WHtR, or WC, was strongly associated with the increase in diabetes prevalence, especially in adults <65.

Association of A1C and Fasting Plasma Glucose Levels With Diabetic Retinopathy Prevalence in the U.S. Population: Implications for diabetes diagnostic thresholds

OBJECTIVE To examine the association of A1C levels and fasting plasma glucose (FPG) with diabetic retinopathy in the U.S. population and to compare the ability of the two glycemic measures to discriminate between people with and without retinopathy. RESEARCH DESIGN AND METHODS This study included 1,066 individuals aged ≥40 years from the 2005–2006 National Health and Nutrition Examination Survey. A1C, FPG, and 45° color digital retinal images were assessed. Retinopathy was defined as a level ≥14 on the Early Treatment Diabetic Retinopathy Study severity scale. We used joinpoint regression to identify linear inflections of prevalence of retinopathy in the association between A1C and FPG. RESULTS The overall prevalence of retinopathy was 11%, which is appreciably lower than the prevalence in people with diagnosed diabetes (36%). There was a sharp increase in retinopathy prevalence in those with A1C ≥5.5% or FPG ≥5.8 mmol/l. After excluding 144 people using hypoglycemic medication, the change points for the greatest increase in retinopathy prevalence were A1C 5.5% and FPG 7.0 mmol/l. The coefficients of variation were 15.6 for A1C and 28.8 for FPG. Based on the areas under the receiver operating characteristic curves, A1C was a stronger discriminator of retinopathy (0.71 [95% CI 0.66–0.76]) than FPG (0.65 [0.60 – 0.70], P for difference = 0.009). CONCLUSIONS The steepest increase in retinopathy prevalence occurs among individuals with A1C ≥5.5% and FPG ≥5.8 mmol/l. A1C discriminates prevalence of retinopathy better than FPG.

Physical Activity, Cardiovascular Fitness, and Insulin Sensitivity Among U.S. Adolescents The National Health and Nutrition Examination Survey, 1999–2002

OBJECTIVE—The purpose of this study was to examine the association of physical activity and cardiovascular fitness (CVF) with insulin sensitivity in a nationally representative sample of U.S. youth. RESEARCH DESIGN AND METHODS—The study included 1,783 U.S. adolescents (11% Mexican American, 14% non-Hispanic black, 63% non-Hispanic white, and 12% other) aged 12–19 years who were examined in the 1999–2002 National Health and Nutrition Examination Survey. Physical activity was assessed by questionnaire and expressed in units of MET hours per week. Predicted maximal oxygen uptake (Vo2max, expressed in milliliters per kilogram of body weight per minute), a measure of CVF, was determined by a submaximal multistage treadmill test. Insulin sensitivity was defined by the Quantitative Insulin Sensitivity Check Index. RESULTS—Boys were more likely than girls to be highly active (≥30 MET h/week; 51 vs. 37%, P < 0.001) and had higher levels of CVF (mean Vo2max 47 vs. 39 ml · kg−1 · min−1, P < 0.001). Sex-specific multiple regression models controlled for age, race/ethnicity, and BMI showed that in boys, high levels of physical activity and high levels of CVF were significantly and positively associated with insulin sensitivity (β = 0.84, P < 0.001 and β = 0.82, P = 0.01, respectively). Among girls, insulin sensitivity was not significantly associated with physical activity or with CVF but was inversely and significantly associated with BMI. CONCLUSIONS—Increasing physical activity and CVF may have an independent effect of improving insulin sensitivity among boys. For girls, the primary role of physical activity may be in weight maintenance.

Identifying Adults at High Risk for Diabetes and Cardiovascular Disease Using Hemoglobin A1c: National Health and Nutrition Examination Survey 2005–2006

BACKGROUND The American Diabetes Association (ADA) recently proposed the use of hemoglobin A1c as a practical and valid strategy to identify high-risk people for whom delivery of an intensive lifestyle intervention to prevent type 2 diabetes is likely to be cost effective. PURPOSE To estimate composite risks of developing diabetes and cardiovascular disease (CVD) for adults with different hemoglobin A1c test results and to compare those risks with those of adults who met the 2003 ADA definition for prediabetes. METHODS Cross-sectional data from the 2005-2006 National Health and Nutrition Examination Survey were analyzed in 2009. The method of Stern and colleagues was used to estimate the 7.5-year probability of type 2 diabetes, and the Framingham General CVD Risk Engine was used to estimate the 10-year probability of CVD for adults with different A1c results. Sample weights were used to account for sampling probability and to adjust for noncoverage and nonresponse. RESULTS Among adults meeting the 2003 ADA definition for prediabetes, the probabilities for incident type 2 diabetes (over 7.5 years) and CVD (over 10 years) were 33.5% and 10.7%, respectively. Use of A1c alone, in the range of 5.5% to <6.5%, would identify a population with comparable risks for diabetes (32.4% [SE=1.2%]) and CVD (11.4% [SE=0.6%]). A slightly higher cutoff (≥5.7%) would identify adults with risks of 41.3% (SE=1.5%) for diabetes and 13.3% (SE=0.8%) for CVD-risks that are comparable to people enrolled in the Diabetes Prevention Program. CONCLUSIONS A1c-based testing in clinical settings should be considered as a means to identify greater numbers of adults at high risk of developing type 2 diabetes and CVD.