Performance of A1C for the classification and prediction of diabetes

Update on Prevention of Cardiovascular Disease in Adults With Type 2 Diabetes Mellitus in Light of Recent Evidence: A Scientific Statement From the American Heart Association and the American Diabetes Association

Cardiovascular disease risk factor control as primary prevention in patients with type 2 diabetes mellitus has changed substantially in the past few years. The purpose of this scientific statement is to review the current literature and key clinical trials pertaining to blood pressure and blood glucose control, cholesterol management, aspirin therapy, and lifestyle modification. We present a synthesis of the recent literature, new guidelines, and clinical targets, including screening for kidney and subclinical cardiovascular disease for the contemporary management of patients with type 2 diabetes mellitus.

Effects of diabetes definition on global surveillance of diabetes prevalence and diagnosis: a pooled analysis of 96 population-based studies with 331,288 participants

BACKGROUND

Diabetes has been defined on the basis of different biomarkers, including fasting plasma glucose (FPG), 2-h plasma glucose in an oral glucose tolerance test (2hOGTT), and HbA1c. We assessed the effect of different diagnostic definitions on both the population prevalence of diabetes and the classification of previously undiagnosed individuals as having diabetes versus not having diabetes in a pooled analysis of data from population-based health examination surveys in different regions.

METHODS

We used data from 96 population-based health examination surveys that had measured at least two of the biomarkers used for defining diabetes. Diabetes was defined using HbA1c (HbA1c ≥6·5% or history of diabetes diagnosis or using insulin or oral hypoglycaemic drugs) compared with either FPG only or FPG-or-2hOGTT definitions (FPG ≥7·0 mmol/L or 2hOGTT ≥11·1 mmol/L or history of diabetes or using insulin or oral hypoglycaemic drugs). We calculated diabetes prevalence, taking into account complex survey design and survey sample weights. We compared the prevalences of diabetes using different definitions graphically and by regression analyses. We calculated sensitivity and specificity of diabetes diagnosis based on HbA1c compared with diagnosis based on glucose among previously undiagnosed individuals (ie, excluding those with history of diabetes or using insulin or oral hypoglycaemic drugs). We calculated sensitivity and specificity in each survey, and then pooled results using a random-effects model. We assessed the sources of heterogeneity of sensitivity by meta-regressions for study characteristics selected a priori.

FINDINGS

Population prevalence of diabetes based on FPG-or-2hOGTT was correlated with prevalence based on FPG alone (r=0·98), but was higher by 2-6 percentage points at different prevalence levels. Prevalence based on HbA1c was lower than prevalence based on FPG in 42·8% of age-sex-survey groups and higher in another 41·6%; in the other 15·6%, the two definitions provided similar prevalence estimates. The variation across studies in the relation between glucose-based and HbA1c-based prevalences was partly related to participants' age, followed by natural logarithm of per person gross domestic product, the year of survey, mean BMI, and whether the survey population was national, subnational, or from specific communities. Diabetes defined as HbA1c 6·5% or more had a pooled sensitivity of 52·8% (95% CI 51·3-54·3%) and a pooled specificity of 99·74% (99·71-99·78%) compared with FPG 7·0 mmol/L or more for diagnosing previously undiagnosed participants; sensitivity compared with diabetes defined based on FPG-or-2hOGTT was 30·5% (28·7-32·3%). None of the preselected study-level characteristics explained the heterogeneity in the sensitivity of HbA1c versus FPG.

INTERPRETATION

Different biomarkers and definitions for diabetes can provide different estimates of population prevalence of diabetes, and differentially identify people without previous diagnosis as having diabetes. Using an HbA1c-based definition alone in health surveys will not identify a substantial proportion of previously undiagnosed people who would be considered as having diabetes using a glucose-based test.

FUNDING

Wellcome Trust, US National Institutes of Health.

Association Between Glycosylated Hemoglobin and Cardiovascular Events and Mortality in Older Adults without Diabetes Mellitus in the General Population: The Leiden 85-Plus Study

OBJECTIVES

To examine the association between glycosylated hemoglobin (HbA1c) and incident cardiovascular disease and mortality in 85-year-old individuals without diabetes mellitus from the general population.

DESIGN

Population-based prospective follow-up study.

SETTING

General population.

PARTICIPANTS

Individuals without known diabetes mellitus (N = 445, n = 291 female).

MEASUREMENTS

HbA1c levels were categorized into three groups (<5.0% (31 mmol/mol), 5.0-5.7% (31-39 mmol/mol; reference), 5.7-6.5% (39-48 mmol/mol)).

RESULTS

At baseline, a history of myocardial infarction (MI) was more prevalent in subjects in the highest HbA1c group (18%) than in the reference group (7%) (P = .001). Prospectively, those with the highest level of HbA1c at baseline had a risk of incident MI during the 5-year follow-up that was 3.6 (95% confidence interval = 1.5-8.3) times as great as that of the reference group. No association was found between HbA1c level and incident stroke, cardiovascular mortality, or all-cause mortality.

CONCLUSION

In individuals aged 85 and older without diabetes mellitus, higher HbA1c is associated with greater risk of MI but not with stroke and mortality.

Cardiometabolic Risk, Socio-Psychological Factors, and Trajectory of Grip Strength Among Older Japanese Adults

OBJECTIVE

To examine the association between cardiometabolic risk (percent body fat [BF%], triglycerides [TG], high-density lipoprotein [HDL]-cholesterol, hemoglobin A1c [HbA1c]), socio-psychological factors (education and self-rated health [SRH]), and trajectories of grip strength (GS) in older adults.

METHOD

Longitudinal 8-year data from 1,381 Japanese adults aged 65 years or above were analyzed using hierarchical linear models, stratified according to gender.

RESULTS

GS declined following a linear trajectory. In both genders, higher BF% was associated with weaker GS, but not with the rate of decline. GS trajectory did not correlate with baseline TG, HDL-C, or HbA1c. Cardiometabolic factors mediated educational differences in GS intercept in both genders. In women, better SRH predicted stronger GS. The effect of SRH was robust to adjustments for cardiometabolic risk.

DISCUSSION

In older adults, GS and its rate of decline are selectively associated with both cardiometabolic risk and socio-psychological characteristics. Cardiometabolic risk mediates educational disparities in GS but not differences in subjective assessments of health.

Comparison of periodontal conditions among three elderly populations in Japan and Germany

AIM

There is a growing interest in comparing periodontal conditions between countries. This study compared periodontal disease conditions in three elderly populations- one from Japan and two from Germany.

MATERIALS AND METHODS

We compared periodontal data of 70-year-old subjects from the Niigata Study with 65-74-year-old subjects from the Study of Health in Pomerania (SHIP) and from West Germany (DMS III). A total of 489, 399 and 549 dentate subjects were analysed, respectively. Recording protocols were standardized. Linear or logistic models were used to compare Niigata Study with SHIP.

RESULTS

Elderly German subjects in SHIP and DMS III had significantly more severe periodontal conditions and fewer remaining teeth compared to those in Niigata Study, though differences were less pronounced for DMS III. German subjects showed a significantly different pattern of various periodontal risk factors compared to Japanese subjects. Even after adjustment for putative periodontal risk factors, SHIP subjects still presented significantly higher adjusted values for most periodontal parameters compared to Niigata Study subjects (p < 0.05).

CONCLUSIONS

Periodontitis was more prevalent in SHIP compared with Niigata Study, even after comprehensive risk factor adjustment. Only to a very small extent, differences between studies could be explained by the risk factors explored.

Blood spot-based measures of glucose homeostasis and diabetes prevalence in a nationally representative population of young US adults

PURPOSE

We investigated understudied biomarker-based diabetes among young US adults, traditionally characterized by low cardiovascular disease risk.

METHODS

We examined 15,701 participants aged 24 to 32 years at Wave IV of the National Longitudinal Study of Adolescent Health (Add Health, 2008). The study used innovative and relatively noninvasive methods to collect capillary whole blood via finger prick at in-home examinations in all 50 states.

RESULTS

Assays of dried blood spots produced reliable and accurate values of HbA1c. Reliability was lower for fasting glucose and lowest for random glucose. Mean (SD) HbA1c was 5.6% (0.8%). More than a quarter (27.4%) had HbA1c-defined prediabetes. HbA1c was highest in the black, non-Hispanic race/ethnic group, inversely associated with education, and more common among the overweight/obese and physically inactive. The prevalence of diabetes defined by previous diagnosis or use of antidiabetic medication was 2.9%. Further incorporating HbA1c and glucose values, the prevalence increased to 6.8%, and among these participants, 38.9% had a previous diagnosis of diabetes (i.e., aware). Among those aware, 37.6% were treated and 64.0% were controlled (i.e., HbA1c < 7%).

CONCLUSIONS

A contemporary cohort of young adults faces a historically high risk of diabetes but there is ample opportunity for early detection and intervention.

Using hemoglobin A1C as a predicting model for time interval from pre-diabetes progressing to diabetes

OBJECTIVE

The early identification of subjects at high risk for diabetes is essential, thus, random rather than fasting plasma glucose is more useful. We aim to evaluate the time interval between pre-diabetes to diabetes with anti-diabetic drugs by using HbA1C as a diagnostic tool, and predicting it using a mathematic model.

METHODS

We used the Taipei Medical University Affiliated Hospital Patient Profile Database (AHPPD) from January-2007 to June-2011. The patients who progressed and were prescribed anti-diabetic drugs were selected from AHPPD. The mathematical model used to predict the time interval of HbA1C value ranged from 5.7% to 6.5% for diabetes progression.

RESULTS

We predicted an average overall time interval for all participants in between 5.7% to 6.5% during a total of 907 days (standard error, 103 days). For each group found among 5.7% to 6.5% we determined 1169.3 days for the low risk group (i.e. 3.2 years), 1080.5 days (i.e. 2.96 years) for the increased risk group and 729.4 days (i.e. 1.99 years) for the diabetes group. This indicates the patients will take an average of 2.49 years to reach 6.5%.

CONCLUSION

This prediction model is very useful to help prioritize the diagnosis at an early stage for targeting individuals with risk of diabetes. Using patients' HbA1C before anti-diabetes drugs are used we predicted the time interval from pre-diabetes progression to diabetes is 2.49 years without any influence of age and gender. Additional studies are needed to support this model for a long term prediction.

Glycosylated hemoglobin A1c as a marker predicting the severity of coronary artery disease and early outcome in patients with stable angina

Background

Glycosylated hemoglobin A1C (HbA1c) has been widely recognized as a marker for predicting the severity of diabetes mellitus (DM) and several cardiovascular diseases. However, whether HbA1c could predict the severity and clinical outcomes in patients with stable coronary artery disease (CAD) remains largely unknown. We determine relationship of HbA1c with severity and outcome in patients with stable CAD.

Methods

We enrolled 1433 patients with stable angina who underwent coronary angiography and were followed up for an average 12 months. The patients were classified into three groups by tertiles of baseline HbA1c level (low group <5.7%, n = 483; intermediate group 5.7 - 6.3%, n = 512; high group >6.3%, n = 438). The relationships between the plasma HbA1c and severity of CAD and early clinical outcomes were evaluated.

Results

High HbA1c was associated with three-vessel disease. Area under the receivers operating characteristic curve (AUC = 0.67, 95% CI: 0.63-0.71, P < 0.001) and multivariate logistic regression analysis suggested that HbA1C was an independent predictor of severity of CAD (OR = 1.60, 95% CI: 1.29-1.99, P < 0.001) even after adjusting for gender, age, risk factor of CAD, lipid profile and fasting blood glucose. During follow-up, 133 patients underwent pre-specified outcomes. After adjusting for multiple variables in the Cox regression model, HbA1C remained to be an independent predictor of poor prognosis (HR = 1.28, 95% CI: 1.12-1.45, P < 0.001).

Conclusions

We concluded that high level of baseline HbA1c appeared to be an independent predictor for the severity of CAD and poor outcome in patients with stable CAD.

Hemoglobin A1c for the diagnosis of diabetes: To replace or to guide oral glucose tolerance tests?

Aims/Introduction:  To evaluate if hemoglobin A1c (A1C) can replace the use of the oral glucose tolerance test (OGTT) to diagnose diabetes in Chinese patients.

Materials and Methods:  Subjects without pre‐existing diabetes were included in this community‐based study. Each participant received a 75‐g OGTT and A1C tests.

Results:  A total of 1362 subjects, 512 men and 850 women, aged 18–88 years, were enrolled. The prevalence of diabetes was 7.4 and 7.3% by OGTT and by A1C ≥ 6.5% criteria, respectively. The optimal A1C cut‐off for diabetes defined by OGTT was 6.1%. The performance of A1C ≥ 6.1% to find diabetes by OGTT was poor, with a kappa 0.50, sensitivity 80% and specificity 91%. Using current criteria of fasting plasma glucose (FPG) < 5.56 mmol/L to exclude and ≥7 mmol/L to diagnose diabetes (FPG criterion), the sensitivity, specificity and OGTT required were 77.2, 100 and 13.5%, respectively. Using A1C < 5.9% to exclude and ≥7.0% to diagnose diabetes (A1C criterion), the sensitivity, specificity and OGTT required were 89.1, 99.8 and 26.5%, respectively. However, using FPG < 5.56 mmol/L and A1C < 6.1% to exclude, and A1C ≥ 7.0% to diagnose diabetes (A1C plus FPG criterion), the sensitivity, specificity and OGTT required were 85.2, 100 and 18.9%, respectively.

Conclusions:  To screen for diabetes, the A1C criterion is more sensitive than the FPG criterion, with more OGTT needed. The A1C plus FPG criterion reduced the number of OGTT needed with acceptable sensitivity. A1C can guide, but cannot replace, OGTT to diagnose diabetes. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00181.x, 2011)

Salivary proteins associated with hyperglycemia in diabetes: a proteomic analysis

Effective monitoring of glucose levels is necessary for patients to achieve greater control over their diabetes. However, only about a quarter of subjects with diabetes who requires close serum glucose monitoring, regularly check their serum glucose daily. One of the potential barriers to patient compliance is the blood sampling requirement. Saliva and its protein contents can be altered in subjects with diabetes, possibly due to changes in glycemic control. We propose here that salivary proteomes of subjects with diabetes may be different based on their glycemic control as reflected in A1C levels. A total of 153 subjects with type 1 or 2 diabetes were recruited. Subjects in each type of diabetes were divided into 5 groups based on their A1C levels; <7, 7-8, 8-9, 9-10, >10. To examine the global proteomic changes associated with A1C, the proteomic profiling of pooled saliva samples from each group was created using label-free quantitative proteomics. Similar proteomic analysis for individual subjects (N=4, for each group) were then applied to examine proteins that may be less abundant in pooled samples. Principle component analysis (PCA) and cluster analysis (p<0.01 and p<0.001) were used to define the proteomic differences. We, therefore, defined the salivary proteomic changes associated with A1C changes. This study demonstrates that differences exist between salivary proteomic profiles in subjects with diabetes based on the A1C levels.

Divergence between HbA1c and fasting glucose through childhood: implications for diagnosis of impaired fasting glucose (Early Bird 52)

OBJECTIVE

An HbA1c threshold of ≥ 6.5% has recently been adopted for the diagnosis of diabetes in adults, and of ≥ 5.7% to identify adults at risk. Little,however, is known of HbA1c's behaviour or diagnostic value in youth. Our aim was to describe the course of HbA1c during childhood, and its association with fasting glucose.

RESEARCH DESIGN AND METHODS

HbA1c and glucose were measured every year in a cohort of 326 healthy children (162 boys) from 5 to 15 years. Mixed effects modelling was used to establish the determinants of HbA1c and its development over time. ROC analysis was used to determine the diagnostic value of HbA1c in the 55 individuals who showed impaired fasting glucose(IFG – glucose ≥ 5.6 mmol/L).

RESULTS

Glucose rose progressively from 4.3 mmol/L at 5 years to 5.1 mmol/Lat 15 years, and although there were positive associations between HbA1c and glucose, from 10 to 13 years, HbA1c fell while glucose continued to rise. IFG developed in 55 children, but HbA1c exceeded 5.7% in only 16 of them. The maximum area under the ROC curve was 0.71 at the age of 14 (p<0.001), and the sensitivity and specificity were optimal at 50 and 80% respectively,corresponding to HbA1c of 5.4%.

CONCLUSIONS

Although HbA1c retains a positive association with glucose throughout childhood, it is weak, and their trends diverge from 10 years,suggesting that factors other than glycaemia systematically influence the variance of HbA1c in youth. These findings therefore limit the interpretation of HbA1c for the diagnosis of IFG during childhood.

Trends in prevalence and control of diabetes in the United States, 1988-1994 and 1999-2010

BACKGROUND

Trends in the prevalence and control of diabetes defined by hemoglobin A1c (HbA1c) levels are important for health care policy and planning.

OBJECTIVE

To update trends in the prevalence of diabetes, prediabetes, and glycemic control.

DESIGN

Cross-sectional.

SETTING

NHANES (National Health and Nutrition Examination Survey) in 1988-1994 and 1999-2010.

PARTICIPANTS

Adults aged 20 years or older.

MEASUREMENTS

We used calibrated HbA1c levels to define undiagnosed diabetes (≥6.5%); prediabetes (5.7% to 6.4%); and, among persons with diagnosed diabetes, glycemic control (<7.0% or <8.0%). Trends in HbA1c categories were compared with fasting glucose levels (≥7.0 mmol/L [≥126 mg/dL] and 5.6 to 6.9 mmol/L [100 to 125 mg/dL]).

RESULTS

In 2010, approximately 21 million U.S. adults aged 20 years or older had total confirmed diabetes (self-reported diabetes or diagnostic levels for both fasting glucose and calibrated HbA1c). During 2 decades, the prevalence of total confirmed diabetes increased, but the prevalence of undiagnosed diabetes remained fairly stable, reducing the proportion of total diabetes cases that are undiagnosed to 11% in 2005-2010. The prevalence of prediabetes was lower when defined by calibrated HbA1c levels than when defined by fasting glucose levels but has increased from 5.8% in 1988-1994 to 12.4% in 2005-2010 when defined by HbA1c levels. Glycemic control improved overall, but total diabetes prevalence was greater and diabetes was less controlled among non-Hispanic blacks and Mexican Americans compared with non-Hispanic whites.

LIMITATION

Cross-sectional design.

CONCLUSION

Over the past 2 decades, the prevalence of total diabetes has increased substantially. However, the proportion of undiagnosed diabetes cases decreased, suggesting improvements in screening and diagnosis. Among the growing number of persons with diagnosed diabetes, glycemic control improved but remains a challenge, particularly among non-Hispanic blacks and Mexican Americans.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Cameras for Public Health Surveillance: A Methods Protocol for Crowdsourced Annotation of Point-of-Sale Photographs

Background

Photographs are an effective way to collect detailed and objective information about the environment, particularly for public health surveillance. However, accurately and reliably annotating (ie, extracting information from) photographs remains difficult, a critical bottleneck inhibiting the use of photographs for systematic surveillance. The advent of distributed human computation (ie, crowdsourcing) platforms represents a veritable breakthrough, making it possible for the first time to accurately, quickly, and repeatedly annotate photos at relatively low cost.

Objective

This paper describes a methods protocol, using photographs from point-of-sale surveillance studies in the field of tobacco control to demonstrate the development and testing of custom-built tools that can greatly enhance the quality of crowdsourced annotation.

Methods

Enhancing the quality of crowdsourced photo annotation requires a number of approaches and tools. The crowdsourced photo annotation process is greatly simplified by decomposing the overall process into smaller tasks, which improves accuracy and speed and enables adaptive processing, in which irrelevant data is filtered out and more difficult targets receive increased scrutiny. Additionally, zoom tools enable users to see details within photographs and crop tools highlight where within an image a specific object of interest is found, generating a set of photographs that answer specific questions. Beyond such tools, optimizing the number of raters (ie, crowd size) for accuracy and reliability is an important facet of crowdsourced photo annotation. This can be determined in a systematic manner based on the difficulty of the task and the desired level of accuracy, using receiver operating characteristic (ROC) analyses. Usability tests of the zoom and crop tool suggest that these tools significantly improve annotation accuracy. The tests asked raters to extract data from photographs, not for the purposes of assessing the quality of that data, but rather to assess the usefulness of the tool. The proportion of individuals accurately identifying the presence of a specific advertisement was higher when provided with pictures of the product’s logo and an example of the ad, and even higher when also provided the zoom tool (χ²₂=155.7, P<.001). Similarly, when provided cropped images, a significantly greater proportion of respondents accurately identified the presence of cigarette product ads (χ²₁=75.14, P<.001), as well as reported being able to read prices (χ²₂=227.6, P<.001). Comparing the results of crowdsourced photo-only assessments to traditional field survey data, an excellent level of correspondence was found, with area under the ROC curves produced by sensitivity analyses averaging over 0.95, requiring on average 10 to 15 crowdsourced raters to achieve values of over 0.90.

Results

Further testing and improvement of these tools and processes is currently underway. This includes conducting systematic evaluations that crowdsource photograph annotation and methodically assess the quality of raters’ work.

Conclusions

Overall, the combination of crowdsourcing technologies with tiered data flow and tools that enhance annotation quality represents a breakthrough solution to the problem of photograph annotation, vastly expanding opportunities for the use of photographs rich in public health and other data on a scale previously unimaginable.

Rational use of electronic health records for diabetes population management

Population management is increasingly invoked as an approach to improve the quality and value of diabetes care. Recent emphasis is driven by increased focus on both costs and measures of care as the US moves from fee for service to payment models in which providers are responsible for costs incurred, and outcomes achieved, for their entire patient population. The capacity of electronic health records (EHRs) to create patient registries, apply analytic tools, and facilitate provider- and patient-level interventions has allowed rapid evolution in the scope of population management initiatives. However, findings on the efficacy of these efforts for diabetes are mixed, and work remains to achieve the full potential of an-EHR based population approach. Here we seek to clarify definitions and key domains, provide an overview of evidence for EHR-based diabetes population management, and recommend future directions for applying the considerable power of EHRs to diabetes care and prevention.

Innovative uses of electronic health records and social media for public health surveillance

Electronic health records (EHRs) and social media have the potential to enrich public health surveillance of diabetes. Clinical and patient-facing data sources for diabetes surveillance are needed given its profound public health impact, opportunity for primary and secondary prevention, persistent disparities, and requirement for self-management. Initiatives to employ data from EHRs and social media for diabetes surveillance are in their infancy. With their transformative potential come practical limitations and ethical considerations. We explore applications of EHR and social media for diabetes surveillance, limitations to approaches, and steps for moving forward in this partnership between patients, health systems, and public health.

Impact of insulin deprivation and treatment on sphingolipid distribution in different muscle subcellular compartments of streptozotocin-diabetic C57Bl/6 mice

Insulin deprivation in type 1 diabetes (T1D) individuals increases lipolysis and plasma free fatty acids (FFA) concentration, which can stimulate synthesis of intramyocellular bioactive lipids such as ceramides (Cer) and long-chain fatty acid-CoAs (LCFa-CoAs). Ceramide was shown to decrease muscle insulin sensitivity, and at mitochondrial levels it stimulates reactive oxygen species production. Here, we show that insulin deprivation in streptozotocin diabetic C57BL/6 mice increases quadriceps muscle Cer content, which was correlated with a concomitant decrease in the body fat and increased plasma FFA, glycosylated hemoglobin level (%Hb A1c), and muscular LCFa-CoA content. The alternations were accompanied by an increase in protein expression in LCFa-CoA and Cer synthesis (FATP1/ACSVL5, CerS1, CerS5), a decrease in the expression of genes implicated in muscle insulin sensitivity (GLUT4, GYS1), and inhibition of insulin signaling cascade by Aktα and GYS3β phosphorylation under acute insulin stimulation. Both the content and composition of sarcoplasmic fraction sphingolipids were most affected by insulin deprivation, whereas mitochondrial fraction sphingolipids remained stable. The observed effects of insulin deprivation were reversed, except for content and composition of LCFa-CoA, CerS protein expression, GYS1 gene expression, and phosphorylation status of Akt and GYS3β when exogenous insulin was provided by subcutaneous insulin implants. Principal component analysis and Pearson's correlation analysis revealed close relationships between the features of the diabetic phenotype, the content of LCFa-CoAs and Cers containing C18-fatty acids in sarcoplasm, but not in mitochondria. Insulin replacement did not completely rescue the phenotype, especially regarding the content of LCFa-CoA, or proteins implicated in Cer synthesis and muscle insulin sensitivity. These persistent changes might contribute to muscle insulin resistance observed in T1D individuals.

Use of HbA1c for diagnoses of diabetes and prediabetes: comparison with diagnoses based on fasting and 2-hr glucose values and effects of gender, race, and age

BACKGROUND

Glycated hemoglobin (HbA1c) has been advocated for the diagnosis of diabetes and prediabetes. Its performance has been commonly assessed in corroboration with elevated fasting plasma glucose (FPG), but not the combination of FPG and 2-hr glucose values. This study assesses receiver operating characteristics (ROC) curves of HbA1c pertaining to the diagnoses of prediabetes and diabetes by FPG and/or 2-hr glucose, and the effects of age, gender, and race.

METHODS

We assessed the utility of HbA1c for diagnosing diabetes and prediabetes among 5395 adults without known diabetes from the National Health and Nutrition Examination Survey (NHANES) 2005-2010.

RESULTS

Current cutoffs of HbA1c for diabetes (6.5%) or prediabetes (5.7%) exhibited low sensitivity (0.249 and 0.354, respectively) and high specificity in identifying patients diagnosed using both FPG and 2-hr glucose, resulting in large false-negative rates (75.1% and 64.9%). Misdiagnosis rates increased with age and in non-Hispanic whites and Mexican Americans. When HbA1c was combined with FPG for diagnoses, the false-negative rate remained high for diabetes (45.7%), but was reduced for prediabetes (9.2%).

CONCLUSIONS

When assessed against diagnoses using both FPG and 2-hr glucose, HbA1c had low sensitivity and high specificity for identifying diabetes and prediabetes, which varied as a function of age and race. Regarding recently released American Diabetes Association (ADA) and joint European guidelines, it is important to consider that HbA1c values below 6.5% and 5.7% do not reliably exclude the presence of diabetes and prediabetes, respectively. Overall, the data argue for greater use of oral glucose tolerance tests (OGTTs) and both FPG and 2-hr glucose values for diagnosis of diabetes and prediabetes.

The progression of cardiometabolic disease: validation of a new cardiometabolic disease staging system applicable to obesity

OBJECTIVE

To validate a Cardiometabolic Disease Staging (CMDS) system for assigning risk level for diabetes, and all-cause and cardiovascular disease (CVD) mortality.

DESIGN AND METHODS

Two large national cohorts, CARDIA and NHANES III, were used to validate CMDS. CMDS: Stage 0: metabolically healthy; Stage 1: one or two metabolic syndrome risk factors [other than impaired fasting glucose (IFG)]; Stage 2: IFG or impaired glucose tolerance (IGT) or metabolic syndrome (without IFG); Stage 3: two of three (IFG, IGT, and/or metabolic syndrome); and Stage 4: type 2 diabetes mellitus/CVD.

RESULTS

In the CARDIA study, compared with Stage 0 metabolically healthy subjects, adjusted risk for diabetes exponentially increased from Stage 1 [hazard ratio (HR) 2.83, 95% confidence interval (CI): 1.76-4.55], to Stage 2 (HR 8.06, 95% CI 4.91-13.2), to Stage 3 (HR 23.5, 95% CI 13.7-40.1) (P for trend <0.001). In NHANES III, both cumulative incidence and multivariable adjusted HRs markedly increased for both all-cause and CVD mortality with advancement of the risk stage from Stages 0 to 4. Adjustment for body mass index (BMI) minimally affected the risks for diabetes and all-cause/CVD mortality using CMDS.

CONCLUSION

CMDS can discriminate a wide range of risk for diabetes, CVD mortality, and all-cause mortality independent of BMI, and should be studied as a risk assessment tool to guide interventions that prevent and treat cardiometabolic disease.

Significance of HbA1c and its measurement in the diagnosis of diabetes mellitus: US experience

The 2014 American Diabetes Association guidelines denote four means of diagnosing diabetes. The first of these is a glycosylated hemoglobin (HbA1c) >6.5%. This literature review summarizes studies (n=47) in the USA examining the significance, strengths, and limitations of using HbA1c as a diagnostic tool for diabetes, relative to other available means. Due to the relatively recent adoption of HbA1c as a diabetes mellitus diagnostic tool, a hybrid systematic, truncated review of the literature was implemented. Based on these studies, we conclude that HbA1c screening for diabetes has been found to be convenient and effective in diagnosing diabetes. HbA1c screening is particularly helpful in community-based and acute care settings where tests requiring fasting are not practical. Using HbA1c to diagnose diabetes also has some limitations. For instance, HbA1c testing may underestimate the prevalence of diabetes, particularly among whites. Because this bias differs by racial group, prevalence and resulting estimates of health disparities based on HbA1c screening differ from those based on other methods of diagnosis. In addition, existing evidence suggests that HbA1c screening may not be valid in certain subgroups, such as children, women with gestational diabetes, patients with human immunodeficiency virus, and those with prediabetes. Further guidelines are needed to clarify the appropriate use of HbA1c screening in these populations.

Impact of metabolic syndrome on the risk of cardiovascular disease mortality in the United States and in Japan

The United States has a higher prevalence of metabolic syndrome (MS) and cardiovascular disease (CVD) mortality than Japan, but it is unknown how much of the difference in MS accounts for the mortality difference. The aim of this study was to examine the impact of MS on the excess CVD mortality in the United States compared with that in Japan. Data from the United States Third National Health and Nutrition Examination Survey (NHANES III; n = 12,561) and the Japanese National Integrated Project for Prospective Observation of Noncommunicable Disease and Its Trends in Aged (NIPPON DATA; n = 7,453) were analyzed. MS was defined as ≥3 of 5 risk factors (obesity, high blood pressure, decreased high-density lipoprotein cholesterol, elevated glycosylated hemoglobin, and elevated triglycerides). The results show that after a median of 13.8 years of follow-up in the United States, 1,683 patients died from CVD (11.75 per 1,000 person-years), and after a median of 15 years of follow-up in Japan, 369 patients died from CVD (3.56 per 1,000 person-years). The age-adjusted prevalence of MS was 26.7% in the United States and 19.3% in Japan. Of 5 MS factors, obesity, high blood pressure, elevated triglycerides, and glycosylated hemoglobin in the United States, and high blood pressure and elevated glycosylated hemoglobin in Japan were significant risk factors for CVD mortality. Estimates of 13.3% and 44% of the excess CVD mortality for the United States could be explained by the higher prevalence of MS and MS plus baseline CVD history than in Japan. In conclusion, the present study is the first to quantitatively demonstrate that MS and MS plus baseline CVD history may significantly contribute to the explanation of excess CVD mortality in the United States compared with Japan.

Elevated HbA1c and fasting plasma glucose in predicting diabetes incidence among older adults: are two better than one?

OBJECTIVE

To determine which measures-impaired fasting glucose (IFG), elevated HbA1c, or both-best predict incident diabetes in older adults.

RESEARCH DESIGN AND METHODS

From the Health, Aging, and Body Composition study, we selected individuals without diabetes, and we defined IFG (100-125 mg/dL) and elevated HbA1c (5.7-6.4%) per American Diabetes Association guidelines. Incident diabetes was based on self-report, use of antihyperglycemic medicines, or HbA1c ≥6.5% during 7 years of follow-up. Logistic regression analyses were adjusted for age, sex, race, site, BMI, smoking, blood pressure, and physical activity. Discrimination and calibration were assessed for models with IFG and with both IFG and elevated HbA1c.

RESULTS

Among 1,690 adults (mean age 76.5, 46% men, 32% black), 183 (10.8%) developed diabetes over 7 years. Adjusted odds ratios of diabetes were 6.2 (95% CI 4.4-8.8) in those with IFG (versus those with fasting plasma glucose [FPG] <100 mg/dL) and 11.3 (7.8-16.4) in those with elevated HbA1c (versus those with HbA1c <5.7%). When FPG and HbA1c were considered together, odds ratios were 3.5 (1.9-6.3) in those with IFG only, 8.0 (4.8-13.2) in those with elevated HbA1c only, and 26.2 (16.3-42.1) in those with both IFG and elevated HbA1c (versus those with normal FPG and HbA1c). Addition of elevated HbA1c to the model with IFG resulted in improved discrimination and calibration.

CONCLUSIONS

Older adults with both IFG and elevated HbA1c have a substantially increased odds of developing diabetes over 7 years. Combined screening with FPG and HbA1c may identify older adults at very high risk for diabetes.

Impact of HbA1c criterion on the definition of glycemic component of the metabolic syndrome: the China health and nutrition survey 2009

BACKGROUND

In 2009, a unified definition of metabolic syndrome (MetS) was proposed, of which, the glycemic component is defined on the basis of fasting plasma glucose (FPG) level. Recently, the American Diabetes Association (ADA) recommended the use of glycated hemoglobin (HbA1c) as an alternative to FPG to define prediabetes. Hence, we aim to compare the performance of HbA1c and FPG in the definition of glycemic component of the MetS among Chinese adults.

METHODS

We conducted a cross-sectional analysis of 7641 Chinese participants aged ≥18 years using data from the China Health and Nutrition Survey 2009. MetS was defined according to the consensus criteria in 2009. We compared the use of HbA1c versus FPG in the definition of the glycemic component of MetS. Increased HbA1c value was defined following the criterion of HbA1c cut-off point of ≥5.7% recommended by the ADA.

RESULTS

Overall, 1136 (14.9%) had MetS according to FPG ≥ 5.6 mmol/l, and 1640 (21.5%) had MetS according to HbA1c ≥ 5.7%. Compared with individuals with FPG-based diagnosis of MetS, individuals with HbA1c-based diagnosis of MetS were older, had higher levels of LDL-C, magnesium, and transferrin, and lower levels of uric acid. Of those found to have MetS according to either FPG or HbA1c (n = 2008), overlap between HbA1c- and FPG-based diagnosis of MetS was limited (n = 768, 38.2%). The overlap index regarding MetS diagnosed by FPG or HbA1c persisted low in each evaluated subgroup (≤ 50.0%).

CONCLUSIONS

We note limited overlap and poor agreement between FPG- and HbA1c-based diagnosis of MetS. Screening MetS through introduction of HbA1c in addition to FPG could contribute to identification of more people with MetS.

The usefulness of glycated hemoglobin A1c (HbA1c) for identifying dysglycemic states in individuals without previously diagnosed diabetes

PURPOSE

We investigated HbA1c's validity as a screening parameter for excluding dysglycemic states in the studied population.

MATERIAL/METHODS

Sensitivity and specificity of HbA1c in some cut-off points were compared with diagnoses based on the oral glucose tolerance test (OGTT) in individuals diagnosed between 2009-2010. Receiver operating characteristic (ROC) analysis for HbA1c was conducted. HbA1c and OGGT measures were done in 441 people (253 women, 187 men, average age 40.1 years (18-79 years)). Based on the OGGT test 37 individuals were diagnosed as diabetic, 28 as impaired glucose tolerant (IGT) and 63 as having impaired fasting glycemia (IFG).

RESULTS

A cut-off value of 6.5% HbA1c classifies diabetic subjects with a sensitivity of 45.9% and specificity of 97.5%. In the investigated population the best cut-off point (the highest sum of the sensitivity and specificity) was 5.9% HbA1c (sensitivity 86.6%, specificity 73%). HbA1c values excluding the risk of dysglycemic states have shown false negative rate in 31.9% when HbA1c was 5.5% and 10.6% when HbA1c was 5.0%.

CONCLUSIONS

Our results indicate that in the investigated population the evaluation of the prevalence of type 2 diabetes using HbA1c values proposed by the American Diabetes Association (ADA) has unsatisfactory sensitivity and detects less than a half of cases of diabetes based on the OGTT diagnoses. HbA1c 5.7% does not have sufficient specificity to identify individuals not being at risk of any disorder of glucose metabolism.

New tools for weight-loss therapy enable a more robust medical model for obesity treatment: rationale for a complications-centric approach

OBJECTIVE

Recent advances in lifestyle intervention programs, pharmacotherapy, and bariatric surgery have enabled the development of medical models for the treatment of obesity. Regarding pharmacotherapy, in 2012 the U.S. Food and Drug Administration approved two new effective and safe weight-loss medications, phentermine/topiramate extended release and lorcaserin, which has greatly augmented options for medically assisted weight loss.

METHODS

The rationale for advantages of a complications-centric medical model over current body mass index (BMI)-centric indications for therapy is examined.

RESULTS

Currently, the baseline BMI level is the principle determinant of indications for obesity treatment using medication and surgery. However, the BMI-centric approach fails to target therapy to those obese patients who will benefit most from weight loss. In contrast, a complications-centric medical model is proposed that will earmark the modality and intensity of the therapeutic intervention based on the presence and severity of complications that can be ameliorated by weight loss.

CONCLUSION

The complications-centric approach to "medicalizing" obesity care employs weight loss primarily as a tool to treat obesity-related complications and promotes the optimization of health outcomes, the benefit/risk ratio, and the cost-effectiveness of therapy.

Awareness of prediabetes--United States, 2005-2010

In 2010, approximately one in three U.S. adults aged≥20 years (an estimated 79 million persons) had prediabetes, a condition in which blood glucose or hemoglobin A1c (A1c) levels are higher than normal but not high enough to be classified as diabetes. Persons with prediabetes are at high risk for developing type 2 diabetes, which accounts for 90%-95% of all cases of diabetes. Each year, 11% of persons with prediabetes who do not lose weight and do not engage in moderate physical activity will progress to type 2 diabetes during the average 3 years of follow-up. Evidence-based lifestyle programs that encourage dietary changes, moderate-intensity physical activity, and modest weight loss can delay or prevent type 2 diabetes in persons with prediabetes. Identifying persons with prediabetes and informing them about their increased risk for type 2 diabetes are first steps in encouraging persons with prediabetes to make healthy lifestyle changes. However, during 2005-2006, only approximately 7% of persons with prediabetes were aware that they had prediabetes. To examine recent changes in awareness of prediabetes and factors associated with awareness among adults aged≥20 years, CDC analyzed data from the National Health and Nutrition Examination Survey (NHANES). This report describes the results of that analysis, which indicated that, during 2009-2010, approximately 11% of those with prediabetes were aware of their condition. Furthermore, during 2005-2010, estimated awareness of prediabetes was <14% across all population subgroups, different levels of health-care access or use, and other factors. In the United States, persons with prediabetes, including those with regular access to health care, might benefit from efforts aimed at making them aware that they are at risk for developing type 2 diabetes and that they can reduce that risk by making modest lifestyle changes. Efforts are needed to increase awareness.

The association between skin collagen glucosepane and past progression of microvascular and neuropathic complications in type 1 diabetes

PURPOSE

We determined the association between novel and acid-labile skin collagen-linked advanced glycation endproducts (AGEs) and the progression of microvascular and neuropathic complications from baseline to near study closeout in the Diabetes Control and Complications Trial (DCCT).

METHODS

From a skin biopsy obtained near the close of the DCCT, proteolytic collagen digests were analyzed by liquid chromatography/mass spectrometry (LC/MS/MS) for glucosepane (GSPNE), glyoxal and methylglyoxal hydroimidazolones (G-H1 and MG-H1) and the glycation product fructose-lysine (FL) using isotope dilution method.

RESULTS

GSPNE and MG-H1 correlated with age and diabetes duration (P<0.02), while GSPNE and FL correlated with the history of glycemia expressed as mean A1c (P≤0.003). Age and duration-adjusted GSPNE and FL levels were lower in intensive (INT) vs. conventional (CONV) treatment subjects in the primary prevention DCCT cohort (P<0.0001), and FL was lower in INT in the secondary intervention cohort (P<0.0001). GSPNE was associated with increased incidence of retinopathy progression (odds ratio (OR) / unit increase in GSPNE: 2.5 for 3 step progression on the ETDRS scale, P=0.003) and sustained≥3 microaneurysms (MA) (OR=4.8, P<0.0001) from DCCT baseline up to the time of the biopsy, and prevalence of microalbuminuria or AER>40mg/24h (OR=5.3, P<0.0001), and confirmed clinical neuropathy (OR=3.4, P=0.015) at the time of the biopsy. GSPNE adjusted for mean A1c remained significant for ≥3 MA (P=0.0252) and AER (P=0.0006). The strong association of complications with A1c was reduced or eliminated when adjusted for GSPNE.

CONCLUSIONS

Glucosepane is a novel AGE marker of diabetic complications that is robustly associated with nephropathic, retinopathic and neuropathic outcomes despite adjustment for A1c, suggesting that it could be one mediator of these complications with possible diagnostic implications.

The metabolic deterioration that antedates diabetes: personal trajectories of HbA(1c) and fasting glucose as early indicators and possible triggers for intervention

HbA(1c) testing has become an accepted means of diagnosing diabetes as an alternative to blood glucose levels. However, population-based norms of glucose and of HbA(1c) levels do not enable the detection of diabetes at an early enough stage to thwart complications. Personal trajectories of glucose levels show steep increases a number of years prior to diabetes diagnosis. Here, we hypothesize that a comparable time-dependent deviation in an individual's HbA(1c) level may be an early manifestation of disease that should prompt lifestyle modifications. We predict that analysis of personal trajectories of glucose and of HbA(1c) will promote earlier intervention and a greater reduction in disease complications than current standards, which are based on population-based norms.

HbA(1c) diagnostic categories and β-cell function relative to insulin sensitivity in overweight/obese adolescents

OBJECTIVE

The recommended HbA(1c) diagnostic categories remain controversial and their utility in doubt in pediatrics. We hypothesized that alterations in the pathophysiologic mechanisms of type 2 diabetes may be evident in the American Diabetes Association recommended at-risk/prediabetes category (HbA(1c) 5.7 to <6.5%).

RESEARCH DESIGN AND METHODS

We compared in vivo hepatic and peripheral insulin sensitivity by [6,6-(2)H(2)] glucose and a 3-h hyperinsulinemic-euglycemic clamp and β-cell function by a 2-h hyperglycemic clamp (∼225 mg/dL) in overweight/obese (BMI ≥85th percentile) adolescents with prediabetes (HbA(1c) 5.7 to <6.5%) (n = 160) to those with normal HbA(1c) (<5.7%) (n = 44). β-Cell function was expressed relative to insulin sensitivity (i.e., the disposition index = insulin sensitivity × first-phase insulin).

RESULTS

In the prediabetes versus normal HbA(1c) category, fasting glucose, insulin, and oral glucose tolerance test (OGTT) area under the curve for glucose and insulin were significantly higher; hepatic and peripheral insulin sensitivity were lower; and β-cell function relative to insulin sensitivity was lower (366 ± 48 vs. 524 ± 25 mg/kg/min; P = 0.005). A total of 27% of youth in the normal HbA(1c) category and 41% in the prediabetes HbA(1c) category had dysglycemia (impaired fasting glucose and/or impaired glucose tolerance) by a 2-h OGTT.

CONCLUSIONS

Overweight/obese adolescents with HbA(1c) in the at-risk/prediabetes category demonstrate impaired β-cell function relative to insulin sensitivity, a metabolic marker for heightened risk of type 2 diabetes. Thus, HbA(1c) may be a suitable screening tool in large-scale epidemiological observational and/or interventional studies examining the progression or reversal of type 2 diabetes risk.

A comparison of periodontal status in the two regional, population-based studies of SHIP and INVEST

OBJECTIVES

To compare the prevalence of periodontal disease between two randomly selected population-based studies (the Oral Infections and Vascular Disease Epidemiology Study (INVEST) and the Study of Health in Pomerania (SHIP)) and address relevant methodological issues.

METHODS

Comparison was restricted to 55- to 81-year olds. Attachment loss (AL), probing depth (PD) and tooth count were assessed in INVEST (full-mouth, six sites) and SHIP (half-mouth, four sites). Subjects were classified according to the CDC/AAP case definition. Recording protocols were standardized. Mixed linear or logistic models were used to compare INVEST with SHIP.

RESULTS

Mean half-mouth AL was lower in INVEST versus SHIP (INVEST: 2.9 mm versus SHIP: 4.0 mm, p < 0.05). Findings were similar across multiple periodontal disease definitions. After equalization of recording protocols and adjustment for periodontal risk factors, mean AL and PD were 1.2 and 0.3 mm lower in INVEST versus SHIP (p < 0.001). The odds for severe periodontitis (CDC/AAP) was 0.2-fold in INVEST versus SHIP (p < 0.001). Confounding effects of age, gender, race/ethnicity, education and use of interdental care devices were highest as indicated by change-in-estimate for study.

CONCLUSION

Implementation of the proposed method for comparison of epidemiological studies revealed that periodontitis was less prevalent in INVEST compared with SHIP, even after extensive risk-factor adjustment.

Alternative markers of hyperglycemia and risk of diabetes

OBJECTIVE

Fructosamine, glycated albumin, and 1,5-anhydroglucitol (1,5-AG) are of interest for monitoring short-term glycemic control in patients with diabetes; however, their associations with diabetes risk are uncharacterized.

RESEARCH DESIGN AND METHODS

We used Cox proportional hazards models to examine the associations of fructosamine, glycated albumin, and 1,5-AG with incident diabetes in 1,299 participants, from the Atherosclerosis Risk in Communities (ARIC) Study (2005-2006), who had no history of diagnosed diabetes at baseline. Incident diabetes was self-reported during annual telephone calls.

RESULTS

There were 119 new cases of diabetes during a median follow-up of 3.3 years. When compared with the lowest quartile, the fourth quartiles of fructosamine and glycated albumin were significantly associated with diabetes risk (hazard ratio [HR] 3.99 [95% CI 1.93-8.28] and 5.22 [2.49-10.94], respectively). The fourth quartile of 1,5-AG was associated with a significantly lower diabetes risk (0.27 [0.14-0.55]). Associations were attenuated but still significant after adjustment for hemoglobin A(1c) (A1C) or fasting glucose.

CONCLUSIONS

Fructosamine, glycated albumin, and 1,5-AG were associated with the subsequent development of diabetes independently of baseline A1C and fasting glucose. Our results suggest these alternative biomarkers may be useful in identifying persons at risk for diabetes.

Accuracy of glycated haemoglobin in screening for pre-diabetes in Asian Indians--a community survey: the Chandigarh Urban Diabetes Study (CUDS)

AIM

To compare American Diabetes Association and International Expert Committee recommended cut-off values of HbA(1c) for detecting the presence of pre-diabetes against plasma glucose values obtained from oral glucose tolerance tests in Asian Indians.

METHODS

A cross-sectional randomly sampled population survey involving 2368 adults, aged ≥ 20 years. HbA(1c) was measured on a Bio-Rad 10 system in 1972 subjects.

RESULTS

Of the 1972 subjects studied, 329 were detected to have pre-diabetes based on isolated impaired fasting glucose in 125 subjects (6.3%), isolated impaired glucose tolerance in 141 subjects (7.1%) and the presence of both in 63 subjects (3.2%). The HbA(1c) cut-off of 34 mmol/mol (5.7%), as recommended by the American Diabetes Association for detecting the presence of pre-diabetes, showed sensitivity of 62%, specificity 77%, with a positive predictive value of 34.7%, a negative predictive value of 89.5% and accuracy of 67.8%; whereas the HbA(1c) cut-off recommended by the International Expert Committee of 42 mmol/mol (6%) had a sensitivity of 36%, specificity of 90%, positive predictive value of 42.7%, negative predictive of 85.4% and an accuracy of 77%. However, both these HbA(1c) cut-offs underdiagnosed the presence of pre-diabetes in 38 and 64% of these subjects, respectively.

CONCLUSIONS

The American Diabetes Association and the International Expert Committee recommended HbA(1c) cut-off values and oral glucose tolerance tests identify different pre-diabetes cohorts. Long-term prospective studies are required to define the usefulness of one over the other.

Screening for pre-diabetes to predict future diabetes using various cut-off points for HbA(1c) and impaired fasting glucose: the Toranomon Hospital Health Management Center Study 4 (TOPICS 4)

AIM

To evaluate various screening criteria for pre-diabetes to identify which combination of impaired fasting glucose and elevated HbA(1c) values performs most effectively in predicting future diabetes in a large cohort of Japanese individuals.

METHODS

The study included 4670 men and 1571 women without diabetes (diabetes: fasting plasma glucose ≥ 7.0 mmol/l, HbA(1c) ≥ 48 mmol/mol (≥ 6.5%), or self-reported clinician-diagnosed diabetes). Pre-diabetes was diagnosed by a combination of impaired fasting glucose (fasting plasma glucose 5.6-6.9 mmol/l or 6.1-6.9 mmol/l) and elevated HbA(1c) [39-46 mmol/mol (5.7-6.4%) or 42-46 mmol/mol (6.0-6.4%)].

RESULTS

During a 5-year follow-up, 338 incident cases of diabetes occurred. The combination of HbA(1c) 39-46 mmol/mol (5.7-6.4%) and fasting plasma glucose 5.6-6.9 mmol/l yielded the highest sensitivity (86%) and generated a large population-attributable per cent risk (78%) for predicting development of diabetes. Among individuals classified as having pre-diabetes by any of the four combined criteria, 20.5-32.0% reverted to the normoglycaemic state as having neither elevated HbA(1c) nor impaired fasting glucose at the last follow-up examination. At 5.6 years after the baseline examination, however, pre-diabetic individuals who fulfilled both HbA(1c) 42-46 mmol/mol (6.0-6.4%) and fasting plasma glucose 6.1-6.9 mmol/l had a 100% cumulative risk of developing diabetes.

CONCLUSIONS

The combination of HbA(1c) 39-46 mmol/mol (5.7-6.4%) and fasting plasma glucose 5.6-6.9 mmol/l would have the best performance in reducing the likelihood of missing future cases of diabetes. Identifying pre-diabetic individuals who strictly fulfil HbA(1c) 42-46 mmol/mol (6.0-6.4%) and fasting plasma glucose 6.1-6.9 mmol/l would predict definite progression to diabetes.

Racial and ethnic differences in cardio-metabolic risk in individuals with undiagnosed diabetes: National Health and Nutrition Examination Survey 1999-2008

BACKGROUND

Although early recognition and treatment of diabetes may be essential to prevent complications, roughly one-fifth of diabetes remains undiagnosed.

OBJECTIVE

Examine cardio-metabolic risk factors and their control in non-Hispanic white (NHW), non-Hispanic black (NHB) and Mexican American (MA) individuals with undiagnosed diabetes.

DESIGN

Nationally representative cross-sectional study of participants in the National Health and Nutrition Examination Survey (NHANES) continuous cycles conducted 1999 through 2008.

PARTICIPANTS

Of 22,621 non-pregnant individuals aged ≥20 years, 2521 had diagnosed diabetes. Of the remaining 20,100 individuals, 17,963 had HbA1c measured, 551 of whom were classified as having undiagnosed diabetes and comprise the study population.

MAIN MEASURES

Undiagnosed diabetes was defined as HbA1c ≥ 6.5% without a self-report of physician diagnosed diabetes. Cardio-metabolic risk factor control was examined using regression methods for complex survey data.

KEY RESULTS

Among individuals with undiagnosed diabetes, mean HbA1c level was 7.7% (95% CI: 7.5, 7.9), 19.3% (95% CI: 14.2, 24.3) smoked, 59.7% (95% CI: 54.5, 64.8%) had hypertension and 96.5% (95% CI: 94.6, 98.4%) had dyslipidemia. Lipid profiles were remarkably different across racial-ethnic groups: NHB had the highest LDL- and HDL-cholesterol, but the lowest triglycerides, while MA had the highest triglycerides and the lowest LDL-cholesterol. After adjusting for age, sex, NHANES examination cycle and use of either blood pressure or lipid medication, the odds of having blood pressure ≥130/80 mmHg was higher in NHB [1.92 (95% CI: 1.09, 3.55)] than NHW, while the odds of having LDL-cholesterol >100 mg/dl was higher in NHW[2.93 (95% CI: 1.37, 6.24)] and NHB[3.34 (95% CI: 1.08, 10.3)] than MA.

CONCLUSIONS

In a nationally representative sample of individuals with undiagnosed diabetes, cardio-metabolic risk factor levels were high across all racial/ethnic groups, but NHB and MA had poorer control compared to NHW. Interventions that target identification of diabetes and treatment of cardio-metabolic risk factors are needed.

Use of HbA(1C) testing to diagnose pre-diabetes in high risk African American children: a comparison with fasting glucose and HOMA-IR

OBJECTIVE

This study aimed to compare the discriminating power of HbA(1C) with other pre-diabetes diagnostic tests specifically in high-risk African American children.

RESEARCH DESIGN AND METHODS

A cross-sectional analysis was performed on a sample of 172 children (70 boys and 102 girls) aged 9-11 years with BMI's above the 85th percentile. Fasting glucose, insulin and HbA(1C) were analyzed from the plasma samples.

RESULTS

Of the 172 participants included in this analysis, 21 (12.2%) had HbA(1C) concentrations above the cutoff of 5.7 used to identify pre-diabetes. None (0%) of these 21 participants, however, were observed to have a glucose concentration above the pre-diabetes cutoff of 110 mg/dl, and only 13 of 21 participants had HOMA-IR above the pre-diabetes cutoff of 2.5. When compared to the previously identified glucose cutoff of 110 mg/dl and HOMA-IR cutoff of 2.5 for pre-diabetes, HbA(1C) showed high specificity (88 and 93%, respectively) but very low sensitivity (0 and 21%, respectively). Glucose, insulin and HOMA-IR were significantly interrelated, but HbA(1C) was not significantly correlated with these biochemical prediabetes assessment variables, nor with anthropometric (BMIz, WC) risk factors.

CONCLUSION

Our results suggest that HbA(1C) had poor discrimination power to identify prediabetes in overweight and obese 9- to 11-year-old African American children. Future studies are recommended to compare the feasibility, sensitivity and predictive power of different screening tests currently recommended to avoid inadequacy when screening for prediabetes and diabetes.

Glycated hemoglobin and risk of hypertension in the atherosclerosis risk in communities study

OBJECTIVE

Diabetes and hypertension often co-occur and share risk factors. Hypertension is known to predict diabetes. However, hyperglycemia also may be independently associated with future development of hypertension. We investigated glycated hemoglobin (HbA(1c)) as a predictor of incident hypertension.

RESEARCH DESIGN AND METHODS

We conducted a prospective analysis of 9,603 middle-aged participants in the Atherosclerosis Risk in Communities Study without hypertension at baseline. Using Cox proportional hazards models, we estimated the association between HbA(1c) at baseline and incident hypertension by two definitions 1) self-reported hypertension during a maximum of 18 years of follow-up and 2) measured blood pressure or hypertension medication use at clinic visits for a maximum of 9 years of follow-up.

RESULTS

We observed 4,800 self-reported and 1,670 visit-based hypertension cases among those without diagnosed diabetes at baseline. Among those with diagnosed diabetes at baseline, we observed 377 self-reported and 119 visit-based hypertension cases. Higher baseline HbA(1c) was associated with an increased risk of hypertension in subjects with and without diabetes. Compared with nondiabetic adults with HbA(1c) <5.7%, HbA(1c) in the prediabetic range (5.7-6.4%) was independently associated with incident self-reported hypertension (hazard ratio 1.14 [95% CI 1.06-1.23]) and visit-detected hypertension (1.17 [1.03-1.33]).

CONCLUSIONS

We observed that individuals with elevated HbA(1c), even without a prior diabetes diagnosis, are at increased risk of hypertension. HbA(1c) is a known predictor of incident heart disease and stroke. Our results suggest that the association of HbA(1c) with cardiovascular risk may be partially mediated by the development of hypertension.

Controversies on how diabetes is diagnosed

PURPOSE OF REVIEW

To evaluate the controversial aspects of diabetes diagnosis.

RECENT FINDINGS

Within the past 2 years, revised guidelines for the diagnosis of diabetes have been issued which endorse the use of the hemoglobin A1C as a diagnostic test, in addition to the previously recommended tests. Updated diagnostic criteria for gestational diabetes were also published in the same period. Recent publications on the current role of oral glucose tolerance tests and diagnosis of diabetes in the acutely ill are sparse. There are new recommendations regarding the use of genetic testing and antibody testing in establishing the cause of diabetes.

SUMMARY

The inclusion of A1C as a diagnostic test has many advantages including reproducibility of the test and convenience, but there are situations where the test is unreliable and it misses many individuals who would have been diagnosed by plasma glucose testing. The diagnostic threshold of 6.5% for the A1C remains controversial. There is still no consensus on the best approach to diagnose gestational diabetes. The role of the oral glucose tolerance test seems to be diminishing. Diagnosis of diabetes in acute illness is aided by A1C testing. Genetic and autoantibody testing in specific situations offer diagnostic and therapeutic utility.

Sensitivity of A1C to diagnose diabetes is decreased in high-risk older Southeast Asians

OBJECTIVE

To determine the effect of ageing on the performance of glycosylated haemoglobin A1C (A1C) for the diagnosis of diabetes mellitus (DM) in Southeast Asians.

METHODS

A1C was measured in 511 subjects (mean age of 52.4 years; range 14-93) undergoing the 75-g oral glucose tolerance test (OGTT). Using receiver operating curve (ROC) analysis, the performance of A1C for the diagnosis of diabetes (using different standard criteria) was compared between 4 groups: <45 (n=156), 45-54 (n=132), 55-64 (n=122), ≥65 years (n=101).

RESULTS

Subjects aged ≥65 years had the highest false-negative rates with fasting plasma glucose (60.8%) and A1C (35.1%), the smallest area under ROC curve (0.723, 95% CI 0.627-0.820), the lowest sensitivity (58.7%, 95% CI 50.4-65.7) and specificity (71.1%, 95% CI 57.3-82.6) of A1C 6.5%, compared to the younger age groups.

CONCLUSION

OGTT is preferable for diagnosis of DM in older Southeast Asian adults.

Impact of introducing HbA1c into the diagnostic criteria on prevalence and cardiovascular risk profiles of individuals with newly diagnosed diabetes in Japan: the Toranomon Hospital Health Management Center Study 2 (TOPICS 2)

OBJECTIVE

To evaluate the impact of HbA1c for diagnosis of diabetes and investigate whether cardiovascular risks profiles differ among individuals with diabetes diagnosed by HbA1c or fasting plasma glucose (FPG).

METHODS

This cross-sectional study involved 26,884 participants (30.6% women; aged 20-91 years) without known diabetes. Subjects were categorized into 4 groups according to the presence or absence of FPG ≥7.0 mmol/L and/or HbA1c ≥6.5%, which were American Diabetes Association criteria. Oral glucose tolerance test data were not available.

RESULTS

Prevalence of undiagnosed diabetes was 3.6%. Of those individuals, 47.5% fulfilled both two criteria and 26.0% fulfilled only HbA1c criterion. Individuals with diabetes according to FPG ≥7.0 mmol/L alone were characterized as having poorly controlled hypertension while those with HbA1c ≥6.5% alone were characterized as older, female, and having lower blood pressure and γ-glutamyltransferase values. Persons with newly diagnosed diabetes by HbA1c had low HDL cholesterol and high LDL or non-HDL cholesterol levels.

CONCLUSIONS

Introducing HbA1c into the diagnosis allowed detection of many previously undiagnosed cases of diabetes in Japanese individuals. Those diagnosed by FPG were characterized by hypertension and those diagnosed by HbA1c had unfavorable lipid profiles, reflecting an atherosclerotic trait.

Predictive value of HbA1c for incident diabetes among subjects with impaired glucose tolerance--analysis of the Indian Diabetes Prevention Programmes

AIMS

The objectives of the study were to assess the predictive value of baseline HbA(1c) for incident diabetes among the participants with impaired glucose tolerance in the Indian Diabetes Prevention Programmes 1 and 2.

METHODS

Data at baseline and at 3-year follow-up were analysed in combined cohorts of the Indian Diabetes Prevention Programmes 1 and 2. Within the 3 years, 324 of the 845 participants developed diabetes (World Health Organization criteria). The predictive value of baseline HbA(1c) for incident diabetes was determined by logistic regression analysis.

RESULTS

Baseline HbA(1c) values had heterogenous distribution. The distribution was similar in isolated impaired glucose tolerance or in impaired glucose tolerance in combination with impaired fasting glucose. A progressive increase in diabetes occurred with increasing HbA(1c). HbA(1c) showed the strongest association with incident diabetes in the multiple logistic regression analysis (odds ratio 3.548, P < 0.0001). The cut-off HbA(1c) of 43 mmol/mol (6.05%) had 67% sensitivity and 60% specificity to predict future diabetes. The diagnostic sensitivity of HbA(1c) of ≥ 48 mmol/mol (≥ 6.5%) was only 51%, with a specificity of 87%, when compared with the oral glucose tolerance glucose values.

CONCLUSIONS

Baseline HbA(1c) was highly predictive of future diabetes in Asian Indian subjects with impaired glucose tolerance and nearly 60% of the incidence occurred with values ≥ 42 mmol/mol (≥ 6.0). Diagnostic sensitivity of HbA(1c) ≥ 48 mmol/mol (≥ 6.5%) for new diabetes was only 51% using the oral glucose tolerance test as the standard for comparison.

Differential response between diabetes and stress-induced hyperglycaemia to algorithmic use of detemir and flexible mealtime aspart among stable postcardiac surgery patients requiring intravenous insulin

AIM

To determine whether an insulin algorithm could be used in a similar manner in the setting of diabetes and stress hyperglycaemia following cessation of intravenous (IV) insulin after cardiac surgery.

METHODS

Subjects who were clinically stable, requiring ≥ 1 unit/h of IV insulin 48 h after surgery, were randomized to once daily detemir at 50, 65 or 80% of IV insulin requirements and received aspart according to carbohydrate intake. Diabetes was defined as any history of diabetes or preoperative HbA1c 6.5%.

RESULTS

The morning glucose in patients with diabetes was 143 mg/dl (n = 61) vs. 124 mg/dl in those with stress hyperglycaemia (n = 21,p = 0.05) on day 1 and 127 vs. 110 mg/dl over 72 h (p = 0.01). This was unaffected by adjustment for initial dosing group. At 72 h, 56% of patients with stress hyperglycaemia reached AM (80-130 mg/dl) and 87% reached overall (80-180 mg/dl) glucose targets, compared to 90 and 100% of patients with stress hyperglycaemia, respectively. There was no difference in hypoglycaemia in patients with stress hyperglycaemia or diabetes. The percentage of patients with diabetes receiving insulin was 46% on admission and 77% at discharge, compared to 0 and 42% of patients with stress hyperglycaemia.

CONCLUSIONS

Following cardiac surgery, patients with stress hyperglycaemia may be converted from IV insulin to detemir with a 50% conversion factor, while patients with diabetes may require a higher conversion factor. Stress hyperglycaemia may be prolonged; the intensity and duration of insulin therapy required for optimal outcomes warrants further examination.

Evaluation of hemoglobin A1c criteria to assess preoperative diabetes risk in cardiac surgery patients

OBJECTIVE

Hemoglobin A1c (A1C) has recently been recommended for diagnosing diabetes mellitus and diabetes risk (prediabetes). Its performance compared with fasting plasma glucose (FPG) and 2-h post-glucose load (2HPG) is not well delineated. We compared the performance of A1C with that of FPG and 2HPG in preoperative cardiac surgery patients.

METHODS

Data from 92 patients without a history of diabetes were analyzed. Patients were classified with diabetes or prediabetes using established cutoffs for FPG, 2HPG, and A1C. Sensitivity and specificity of the new A1C criteria were evaluated.

RESULTS

All patients diagnosed with diabetes by A1C also had impaired fasting glucose, impaired glucose tolerance, or diabetes by other criteria. Using FPG as the reference, sensitivity and specificity of A1C for diagnosing diabetes were 50% and 96%, and using 2HPG as the reference they were 25% and 95%. Sensitivity and specificity for identifying prediabetes with FPG as the reference were 51% and 51%, respectively, and with 2HPG were 53% and 51%, respectively. One-third each of patients with prediabetes was identified using FPG, A1C, or both. When testing A1C and FPG concurrently, the sensitivity of diagnosing dysglycemia increased to 93% stipulating one or both tests are abnormal; specificity increased to 100% if both tests were required to be abnormal.

CONCLUSIONS

In patients before cardiac surgery, A1C criteria identified the largest number of patients with diabetes and prediabetes. For diagnosing prediabetes, A1C and FPG were discordant and characterized different groups of patients, therefore altering the distribution of diabetes risk. Simultaneous measurement of FGP and A1C may be a more sensitive and specific tool for identifying high-risk individuals with diabetes and prediabetes.

Hemoglobin A1c as a tool for the diagnosis of type 2 diabetes in 208 premenopausal women with polycystic ovary syndrome

OBJECTIVE

To study hemoglobin A1c (HbA1c) as a tool for diagnosing diabetes and to study HbA1c as a cardiovascular risk marker in patients with polycystic ovary syndrome (PCOS).

DESIGN

Retrospective observational study.

SETTING

Academic tertiary-care medical center.

PATIENT(S)

Two hundred eight premenopausal women with PCOS.

INTERVENTION(S)

Patients underwent clinical evaluation (Ferriman-Gallwey score, body mass index, waist, blood pressure), hormone analyses (T, sex hormone-binding globulin, fasting lipids, insulin, glucose, HbA1c), transvaginal ultrasound, and 2-hour oral glucose tolerance tests (OGTT) measuring capillary blood glucose (BG) at 0 (BG 0) and 120 (BG 120) minutes, insulin, and C-peptide.

MAIN OUTCOME MEASURE(S)

Results of OGTT, HbA1c values.

RESULT(S)

Twenty patients were diagnosed with type 2 diabetes during OGTT. The sensitivity and specificity of HbA1c ≥6.5% for the diagnosis of diabetes were 35% and 99%, respectively, compared with the diagnosis established by OGTT. Hemoglobin A1c showed closer correlation with waist, body mass index, and lipid profile than BG 120, suggesting that HbA1c could be a cardiovascular risk marker.

CONCLUSION(S)

The clinical utility of HbA1c for diagnosing impaired glucose tolerance and type 2 diabetes in PCOS in daily practice is low. Long-term prospective studies are needed to determine whether HbA1c is superior to glucose levels as a cardiovascular risk marker in patients with PCOS.

Comparison of hemoglobin A1c with fasting plasma glucose and 2-h postchallenge glucose for risk stratification among women with recent gestational diabetes mellitus

OBJECTIVE

Postpartum testing with a 75-g 2-h oral glucose tolerance test or fasting plasma glucose (FPG) alone is often not performed among women with histories of gestational diabetes mellitus (GDM). Use of hemoglobin A(1c) (A1C) might increase testing. The association between A1C and glucose has not been examined in women with histories of GDM.

RESEARCH DESIGN AND METHODS

We assessed the association of A1C ≥5.7% with FPG ≥100 mg/dL and 2-h glucose ≥140 mg/dL among 54 women with histories of GDM between 6 weeks and 36 months postpartum.

RESULTS

A1C ≥5.7% had 65% sensitivity and 68% specificity for identifying elevated FPG or 2-h glucose and 75% sensitivity and 62% specificity for elevated FPG alone. The area under the receiver operating characteristic curve for A1C was 0.76 for elevated FPG or 2-h glucose and 0.77 for elevated FPG alone.

CONCLUSIONS

The agreement between A1C and glucose levels is fair for detection of abnormal glucose tolerance among women with histories of GDM.

HbA1c 5·7-6·4% and impaired fasting plasma glucose for diagnosis of prediabetes and risk of progression to diabetes in Japan (TOPICS 3): a longitudinal cohort study

BACKGROUND

The clinical relevance of the diagnostic criteria for prediabetes to prediction of progression to diabetes has been little studied. We aimed to compare the prevalence of prediabetes when assessed by the new glycated haemoglobin A(1c) (HbA(1c)) 5·7-6·4% criterion or by impaired fasting glucose, and assessed differences in progression rate to diabetes between these two criteria for prediabetes in a Japanese population.

METHODS

Our longitudinal cohort study included 4670 men and 1571 women aged 24-82 years without diabetes at baseline (diabetes was defined as fasting plasma glucose ≥7·0 mmol/L, self-reported clinician-diagnosed diabetes, or HbA(1c) ≥6·5%) who attended Toranomon Hospital (Tokyo, Japan) for a routine health check between 1997 and 2003. Participants with a baseline diagnosis of prediabetes according to impaired fasting glucose (fasting plasma glucose 5·6-6·9 mmol/L) or HbA(1c) 5·7-6·4%, or both, were divided into four groups on the basis of baseline diagnosis of prediabetes. Rate of progression to diabetes was assessed annually.

FINDINGS

Mean follow-up was 4·7 (SD 0·7) years. 412 (7%) of 6241 participants were diagnosed with prediabetes on the basis of the HbA(1c) 5·7-6·4% criterion. Screening by HbA(1c) alone missed 1270 (61%) of the 2092 prediabetic individuals diagnosed by a combination of impaired fasting glucose and HbA(1c) 5·7-6·4%. Overall cumulative probability of progression to diabetes did not differ significantly between participants with prediabetes discordantly diagnosed by either HbA(1c) or impaired fasting glucose alone (incidence was 7% for HbA(1c) alone [n=412 individuals and 30 incident cases] and 9% for impaired fasting glucose alone [n=1270, 108 cases]; log-rank test, p=0·3317). Multivariate-adjusted hazard ratios for incident diabetes were 6·16 (95% CI 4·33-8·77) for those diagnosed with prediabetes by impaired fasting glucose alone and 6·00 (3·76-9·56) for diagnosis by HbA(1c) alone, and were substantially increased to 31·9 (22·6-45·0) for diagnosis by both impaired fasting glucose and HbA(1c) compared with normoglycaemic individuals.

INTERPRETATION

Diagnosis of prediabetes by both the new HbA(1c) criterion and impaired fasting glucose identified individuals with an increased risk of progression to diabetes. Although the new HbA(1c) criterion identified fewer individuals at high risk than did impaired fasting glucose, the predictive value for progression to diabetes assessed by HbA(1c) 5·7-6·4% was similar to that assessed by impaired fasting glucose alone. The two tests used together could efficiently target people who are most likely to develop diabetes and allow for early intervention.

FUNDING

Japan Society for the Promotion of Science; Ministry of Health Labor and Welfare, Japan.

Glycated haemoglobin and cognitive decline: the Atherosclerosis Risk in Communities (ARIC) study

AIMS/HYPOTHESIS

This study aimed to examine the association between diabetes and hyperglycaemia-assessed by HbA(1c)-and change in cognitive function in persons with and without diabetes.

METHODS

This was a prospective cohort study of 8,442 non-diabetic and 516 diabetic participants in the Atherosclerosis Risk in Communities (ARIC) study. We examined the association of baseline categories of HbA(1c) with 6 year change in three measures of cognition: the digit symbol substitution test (DSST); the delayed word recall test (DWRT); and the word fluency test (WFT). Our primary outcomes were the quintiles with the greatest annual cognitive decline for each test. Logistic regression models were adjusted for demographic (age, sex, race, field centre, education, income), lifestyle (smoking, drinking) and metabolic (adiposity, blood pressure, cholesterol) factors.

RESULTS

The mean age was 56 years. Women accounted for 56% of the study population and 21% of the study population were black. The mean HbA(1c) was 5.7% overall: 8.5% in persons with and 5.5% in persons without diabetes. In adjusted logistic regression models, diagnosed diabetes was associated with cognitive decline on the DSST (OR 1.42, 95% CI 1.14-1.75, p = 0.002), but HbA(1c) was not a significant independent predictor of cognitive decline when stratifying by diabetes diagnosis (diabetes, p trend = 0.320; no diabetes, p trend = 0.566). Trends were not significant for the DWRT or WFT in either the presence or the absence of diabetes.

CONCLUSIONS/INTERPRETATION

Hyperglycaemia, as measured by HbA(1c), did not add predictive power beyond diabetes status for 6 year cognitive decline in this middle-aged population. Additional work is needed to identify the non-glycaemic factors by which diabetes may contribute to cognitive decline.

Glycated hemoglobin predicts all-cause, cardiovascular, and cancer mortality in people without a history of diabetes undergoing coronary angiography

OBJECTIVE

Glycated hemoglobin has been suggested to be superior to fasting glucose for the prediction of vascular disease and death from any cause. The aim of the present work was to analyze and compare the predictive value of glycated hemoglobin and fasting glucose on all-cause and cause-specific mortality in subjects who underwent coronary angiography.

RESEARCH DESIGN AND METHODS

We studied 2,686 participants of the Ludwigshafen Risk and Cardiovascular health study without a history of diabetes. The majority of this cohort had coronary artery disease. Glycated hemoglobin was measured at the baseline examination. The mean (± SD) duration of the follow-up for all-cause, cardiovascular, and cancer mortality was 7.54 ± 2.1 years.

RESULTS

A total of 508 deaths occurred during the follow-up. Of those, 299 were accounted for by cardiovascular diseases and 79 by cancer. Baseline glycated hemoglobin was predictive of all-cause, cardiovascular, and cancer mortality. The multivariable-adjusted hazard ratios (HR) (95% CI) for glycated hemoglobin values of <5.0, 5.0-5.4, 5.5-5.9, 6.0-6.4, 6.5-7.4, and ≥7.5% for all-cause mortality were 1.36 (0.85-2.18), 1.00 (0.76-1.32), 1.00 (reference), 1.11 (0.88-1.41), 1.39 (1.07-1.82), and 2.15 (1.32-3.53), respectively. Similar J-shaped relationships were found between glycated hemoglobin and cardiovascular and cancer mortality. The associations of glycated hemoglobin with all-cause and cardiovascular mortality remained significant after inclusion of fasting glucose as a covariate. However, fasting glucose was not significantly related to mortality when adjusting for glycated hemoglobin.

CONCLUSIONS

Glycated hemoglobin significantly and independently of fasting glucose predicts all-cause and cardiovascular mortality in whites at intermediate to high cardiovascular risk.