OBJECTIVE
Hemoglobin A1c (A1C) has emerged as a recommended diagnostic tool for identifying diabetes and subjects at risk for the disease. This recommendation is based on data in adults showing the relationship between A1C with future development of diabetes and microvascular complications. However, studies in the pediatric population are lacking.RESEARCH DESIGN AND METHODS
We studied a multiethnic cohort of 1,156 obese children and adolescents without a diagnosis of diabetes (male, 40%/female, 60%). All subjects underwent an oral glucose tolerance test (OGTT) and A1C measurement. These tests were repeated after a follow-up time of ∼2 years in 218 subjects.RESULTS
At baseline, subjects were stratified according to A1C categories: 77% with normal glucose tolerance (A1C <5.7%), 21% at risk for diabetes (A1C 5.7–6.4%), and 1% with diabetes (A1C >6.5%). In the at risk for diabetes category, 47% were classified with prediabetes or diabetes, and in the diabetes category, 62% were classified with type 2 diabetes by the OGTT. The area under the curve receiver operating characteristic for A1C was 0.81 (95% CI 0.70–0.92). The threshold for identifying type 2 diabetes was 5.8%, with 78% specificity and 68% sensitivity. In the subgroup with repeated measures, a multivariate analysis showed that the strongest predictors of 2-h glucose at follow-up were baseline A1C and 2-h glucose, independently of age, ethnicity, sex, fasting glucose, and follow-up time.CONCLUSIONS
The American Diabetes Association suggested that an A1C of 6.5% underestimates the prevalence of prediabetes and diabetes in obese children and adolescents. Given the low sensitivity and specificity, the use of A1C by itself represents a poor diagnostic tool for prediabetes and type 2 diabetes in obese children and adolescents.After years of debate, the American Diabetes Association (ADA) published revised recommendations to use hemoglobin A1c (A1C) to diagnose diabetes and to identify subjects at risk for developing diabetes in the future (1). The decision is based on numerous cross-sectional and longitudinal studies showing the correlation between A1C and diabetes at baseline or long-term association between A1C and risk of diabetes and diabetes-related comorbidities (1–6). Additional factors influencing this decision were as follows: A1C does not require a fasting state, reflects the usual 3–4 months before glycemia, has low intraindividual variability, and is a good predictor of diabetes-related complications (1,5). It should be noted that this decision was made only on studies performed in adults. Little is known about the use of the A1C test for the diagnosis of type 2 diabetes and prediabetes in childhood and adolescence. In view of the fact that both prediabetes and, more important, type 2 diabetes have recently emerged as early complications of childhood obesity (7), it is of critical importance to diagnose these forms of dysglycemia early in their development. Thus, the aim of this study was to assess the diagnostic utility of A1C for the diagnosis of prediabetes and type 2 diabetes in obese children and adolescents. We therefore conducted this study to evaluate the following: 1) the distribution of A1C levels in a multiethnic cohort of obese children and adolescents without known diabetes and 2) the sensitivity and specificity of A1C for type 2 diabetes and prediabetes diagnoses compared with the current oral glucose tolerance test (OGTT) gold standard. 相似文献OBJECTIVE
We evaluated whether cardiometabolic risk profiles differ for subjects identified as having prediabetes by A1C, fasting glucose (FPG), or 2-h postchallenge glucose (2-PG) criteria.RESEARCH DESIGN AND METHODS
Atherosclerosis risk factors, oral glucose tolerance test, and ultrasound measurement of carotid intima–media thickness (IMT) were analyzed in 780 nondiabetic individuals.RESULTS
Poor agreement existed for A1C and FPG criteria for identification of subjects with prediabetes (κ coefficient = 0.332). No differences in cardiometabolic risk profiles were observed among the three groups of individuals with prediabetes by A1C only, FPG only, and both A1C and FPG. Poor agreement also existed for A1C and 2-PG criteria for identification of individuals with prediabetes (κ coefficient = 0.299). No significant differences in cardiometabolic risk factors were observed between IGT-only and individuals with prediabetes by A1C and 2-PG. Compared with subjects with prediabetes identified by A1C only, IGT-only individuals exhibited a worse cardiometabolic risk profile, with significantly higher systolic blood pressure, pulse pressure, 2-h postchallenge insulin, triglycerides, high-sensitivity C-reactive protein, and carotid IMT, and lower HDL cholesterol levels and insulin sensitivity.CONCLUSIONS
These results suggest that considerable discordance between A1C, FPG, and 2-PG exists for the identification of individuals with prediabetes and that the cardiometabolic risk profile of these individuals varies by metabolic parameter, with 2-PG showing the stronger association with cardiometabolic risk factors and subclinical atherosclerosis than FPG or A1C.Hemoglobin A1c (A1C) is an integrated measure of average blood glucose concentrations over the preceding 2–3 months and is widely used for monitoring metabolic control in individuals with diabetes (1). Recently, the American Diabetes Association (ADA) has revised criteria for the diagnosis of type 2 diabetes and the categories at increased risk for diabetes already including impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) on the basis of an ample analysis performed by an international expert committee (2,3) recommending the use of A1C measurements as another diagnostic test option in addition to glucose values. Specifically for the categories of increased risk for type 2 diabetes, the new ADA recommendations state that an A1C from 5.7 to 6.4% identifies individuals at high risk for diabetes to whom the term prediabetes may be applied (2).A1C measurements offer some practical advantages over assessments of fasting plasma glucose (FPG) or glucose levels during an oral glucose tolerance test (OGTT), including lower day-to-day variability, less perturbations during periods of stress or illness, and requirement of a nonfasting sample (3). However, the A1C measure may identify distinct subjects at increased risk for type 2 diabetes compared with IFG and IGT, and if extensively implemented, may to some extent change the present epidemiologic setting of these dysglycemic conditions. Although it would be desirable for fasting glucose, 2-h postchallenge glucose, and A1C values to be equivalent in identifying at-risk subjects, a poor concordance among the three prediabetes categories has been reported in different ethnic groups (4–10).Early detection of individuals at high risk for type 2 diabetes is essential not only for prevention of diabetes itself but also of the associated cardiovascular complications. Indeed, the risk of cardiovascular disease is already increased before glucose levels reach the diagnostic threshold of diabetes, and 2-h postchallenge glucose has been reported to be a better predictor of cardiovascular disease than FPG (11,12). However, A1C was shown to be a better predictor of cardiovascular disease than FPG (13). Head-to-head comparisons between 2-h postchallenge glucose and A1C as predictors of cardiovascular disease have been focused on mortality, and results are controversial (14–16).In consideration of the expected augmented use of A1C as a screening tool to identify individuals with dysglycemic conditions, it would be important to evaluate the effect of the new ADA recommendations for prediabetes definition on the ability to identify individuals who are at increased risk for a number of adverse clinical outcomes. In the current study, we examined the concordance of A1C, FPG, or 2-h postchallenge glucose tests for the identification of prediabetes in a cohort of Italian Caucasians. We also evaluated whether metabolic and cardiovascular risk factors, including carotid preclinical atherosclerosis, differ for subjects identified as having prediabetes by each of these criteria. 相似文献OBJECTIVE
We compared A1C and fasting plasma glucose (FPG) in predicting cardiovascular disease (CVD) in a population with widespread obesity and diabetes.RESEARCH DESIGN AND METHODS
A total of 4,549 American Indian adults underwent the Strong Heart Study (SHS) baseline examination (1989–1991). Data from 3,850 individuals (60% women) with baseline measurements of FPG and A1C and no prevalent CVD were analyzed; 1,386 had known diabetes. CVD events were ascertained over a median of 15 years.RESULTS
A1C ≥6.5% had a 44.3% sensitivity and 98.9% specificity to identify participants with FPG ≥126 mg/dL. Increases in A1C were associated with adverse CVD risk factor profiles; individuals with known diabetes had worse profiles. For A1C <5, 5 to <5.5, 5.5 to <6, 6–6.5, or ≥6.5% or known diabetes, the multivariate-adjusted hazard ratio (HR) [95% CI] for coronary heart disease (CHD) was significant only for individuals with known diabetes (2.76 [2.17–3.51]). Similarly, the adjusted HRs for total CVD were significant only for individuals with A1C ≥6.5% or known diabetes (1.50 [1.10–2.04] and 2.52 [2.06–3.08], respectively). Similar results were observed for FPG.CONCLUSIONS
Individuals with known or newly diagnosed diabetes had increased risk for CVD. Although A1C is more convenient than FPG in diagnosing diabetes, neither test adds to conventional CVD risk factors in predicting CHD or total CVD.Fasting plasma glucose (FPG) has been the standard measure for diagnosing diabetes (1). Hemoglobin A1c (A1C) ≥6.5% has been offered as an alternative diagnostic criterion (2) on the basis of the relationship between A1C and microvascular complications. A1C and FPG measure differing aspects of glucose metabolism; A1C measures chronic glycemia (during the previous 2–3 months), while FPG primarily reflects hepatic glucose output at the time of sampling. As expected, A1C identifies different individuals as diabetic than does FPG (3). Additionally, it was reported (4) in a predominantly white cohort with low prevalence of obesity or diabetes that increments of A1C >5.5% predict significantly increased risk for coronary heart disease (CHD) and stroke, whereas FPG of 100–126 mg/dL does not.Many U.S. minority populations have high rates of obesity, insulin resistance, and diabetes (5,6). We recently reported that A1C alone identifies fewer diabetes cases than FPG, and neither FPG nor A1C alone can identify all diabetes cases (7). Because the Strong Heart Study (SHS) cohort had a high prevalence of obesity and type 2 diabetes >20 years ago, it serves as a model for other minority populations experiencing epidemics of these disorders (8). In this article, cardiovascular disease (CVD) incidence by A1C category will be examined, and the value of A1C and FPG in predicting CVD will be compared. 相似文献OBJECTIVE
Hemoglobin A1c (HbA1c) is recommended for identifying diabetes and prediabetes. Because HbA1c does not fluctuate with recent eating or acute illness, it can be measured in a variety of clinical settings. Although outpatient studies identified HbA1c-screening cutoff values for diabetes and prediabetes, HbA1c-screening thresholds have not been determined for acute-care settings. Using follow-up fasting blood glucose (FBG) and the 2-h oral glucose tolerance test (OGTT) as the criterion gold standard, we determined optimal HbA1c-screening cutoffs for undiagnosed dysglycemia in the emergency department setting.RESEARCH DESIGN AND METHODS
This was a prospective observational study of adults aged ≥18 years with no known history of hyperglycemia presenting to an emergency department with acute illness. Outpatient FBS and 2-h OGTT were performed after recovery from the acute illness, resulting in diagnostic categorizations of prediabetes, diabetes, and dysglycemia (prediabetes or diabetes). Optimal cutoffs were determined and performance data identified for cut points.RESULTS
A total of 618 patients were included, with a mean age of 49.7 (±14.9) years and mean HbA1c of 5.68% (±0.86). On the basis of an OGTT, the prevalence of previously undiagnosed prediabetes and diabetes was 31.9 and 10.5%, respectively. The optimal HbA1c-screening cutoff for prediabetes was 5.7% (area under the curve [AUC] = 0.659, sensitivity = 55%, and specificity = 71%), for dysglycemia 5.8% (AUC = 0.717, sensitivity = 57%, and specificity = 79%), and for diabetes 6.0% (AUC = 0.868, sensitivity = 77%, and specificity = 87%).CONCLUSIONS
We identified HbA1c cut points to screen for prediabetes and diabetes in an emergency department adult population. The values coincide with published outpatient study findings and suggest that an emergency department visit provides an opportunity for HbA1c-based dysglycemia screening.There are 26.8 million people with diabetes in the U.S., and by the year 2030, it is estimated to increase to 36 million people (1). Current estimates are that 27% of individuals with diabetes remain undiagnosed, and by the time of diagnosis, there often are microvascular and macrovascular abnormalities found (2–4). Early recognition is important because lifestyle modifications and medications can reduce the incidence of diabetes in people at high risk (5), and the treatment of diabetes can prevent or delay microvascular end-organ complications.The use of hemoglobin A1c (HbA1c) to diagnose prediabetes and diabetes recently was recommended by the American Diabetes Association (ADA) (6). HbA1c testing has an advantage over glucose-based testing because it does not require fasting, and the test can be performed at any time. Guidelines recommend an HbA1c ≥6.5% to diagnose diabetes and HbA1c between 5.7 and 6.4% for identifying prediabetes. These cutoff values for HbA1c are derived in part from outpatient studies and are based on populations of those not acutely ill at the time of testing (7–9).Less attention has been given to screening and diagnosing diabetes and prediabetes in acute-care settings such as the emergency department, where blood is routinely drawn to manage acute illness and clinicians are available to interpret the results. The HbA1c test can be quickly performed in many different clinical settings, including the hospital. However, it is not known whether HbA1c thresholds differ between the higher-risk acute-care and the general outpatient populations. The purpose of this study was to determine optimal HbA1c-screening cutoff points for undiagnosed dysglycemia in the emergency department setting using follow-up fasting blood glucose (FBS) and 2-h oral glucose tolerance tests (OGTTs) as the criterion gold standard. 相似文献- KEY MESSAGES
HbA1c level was positively associated with the proportion of participants with a high UACR and logUACR in participants without DM.
For participants without MetS, the proportion of participants with a high UACR was greater in the High group than in the other groups and logUACR was greatest in the High group compared to the other groups.
For participants with MetS, there were significant associations between HbA1c and the proportion of participants with a high UACR as a categorical variable or logUACR as a continuous variable, but the statistical significance of this finding was weak. No differences were found for proportions of participants with high UACR and logUACR values in the Low, Middle, and High groups.