Differences in A1C by race and ethnicity among patients with impaired glucose tolerance in the Diabetes Prevention Program

Do glycemic marker levels vary by race? Differing results from a cross-sectional analysis of individuals with and without diagnosed diabetes

OBJECTIVE

It is well known that A1c varies by race. However, racial differences in other biomarkers of hyperglycemia are less well characterized. The objective of this study was to determine whether average levels of glycemic markers differ by race in adults with and without diagnosed diabetes, before and after accounting for postchallenge glucose.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 2692 middle-aged men and women (5.5% with diagnosed diabetes; 44% African-American; and 56% white) from the Coronary Artery Risk Development in Young Adults Study (2005-2006) who had fasting glucose, 2-hour postchallenge glucose, A1c, glycated albumin, fructosamine, and 1,5-anhydroglucitol (1,5-AG) measured. Multiple linear regression was used to evaluate racial differences in mean levels of each glycemic marker stratified by the diabetes status and adjusted for sociodemographics, cardiovascular factors, and postchallenge glucose.

RESULTS

Among those with diagnosed diabetes, racial differences were not observed for any of the glycemic markers. In contrast, among those without diagnosed diabetes, African-Americans had higher mean levels than whites of A1c (β=0.19% points; 95% CI 0.14 to 0.24), glycated albumin (β=0.82% points; 95% CI 0.68 to 0.97), fructosamine (β=8.68 μmol/L; 95% CI 6.68 to 10.68), and 2-hour glucose (β=3.50 mg/dL; 95% CI 0.10 to 6.90) after multivariable adjustment, whereas there were no statistically significant racial difference in 1,5-AG. The racial differences observed for A1c, glycated albumin, and fructosamine persisted after further adjustment for fasting and 2-hour glucose and were of similar magnitude (SD units).

CONCLUSIONS

Racial differences in glycemic marker levels were evident among middle-aged adults without diagnosed diabetes even after adjustment for postchallenge glucose. Whether these racial differences in biomarkers of hyperglycemia affect the risk of complications warrants additional study.

Differences in Hemoglobin A1c Between Hispanics/Latinos and Non-Hispanic Whites: An Analysis of the Hispanic Community Health Study/Study of Latinos and the 2007-2012 National Health and Nutrition Examination Survey

OBJECTIVE

To determine whether, after adjustment for glycemia and other selected covariates, hemoglobin A1c (HbA1c) differed among adults from six Hispanic/Latino heritage groups (Central American, Cuban, Dominican, Mexican, Puerto Rican, and South American) and between Hispanic/Latino and non-Hispanic white adults without self-reported diabetes.

RESEARCH DESIGN AND METHODS

We performed a cross-sectional analysis of data from 13,083 individuals without self-reported diabetes from six Hispanic/Latino heritage groups, enrolled from 2008 to 2011 in the Hispanic Community Health Study/Study of Latinos, and 2,242 non-Hispanic white adults enrolled during the 2007-2012 cycles of the National Health and Nutrition Examination Survey. We compared HbA1c levels among Hispanics/Latinos and between Hispanics/Latinos and non-Hispanic whites before and after adjustment for age, sex, fasting (FPG) and 2-h post-oral glucose tolerance test (2hPG) glucose, anthropometric measurements, and selected biochemical and hematologic variables and after stratification by diabetes status: unrecognized diabetes (FPG ≥7.1 mmol/L or 2hPG ≥11.2 mmol/L), prediabetes (FPG 5.6-7.0 mmol/L or 2hPG 7.8-11.1 mmol/L), and normal glucose tolerance (FPG <5.6 mmol/L and 2hPG <7.8 mmol/L).

RESULTS

Adjusted mean HbA1c differed significantly across all seven groups (P < 0.001). Non-Hispanic whites had significantly lower HbA1c (P < 0.05) than each individual Hispanic/Latino heritage group. Upon stratification by diabetes status, statistically significant differences (P < 0.001) in adjusted mean HbA1c persisted across all seven groups.

CONCLUSIONS

HbA1c differs among Hispanics/Latinos of diverse heritage groups and between non-Hispanic whites and Hispanics/Latinos after adjustment for glycemia and other covariates. The clinical significance of these differences is unknown.

Association of HbA1c with hospitalization and mortality among patients with heart failure and diabetes

Background

Comorbid diabetes is common in heart failure and associated with increased hospitalization and mortality. Nonetheless, the association between glycemic control and outcomes among patients with heart failure and diabetes remains poorly characterized, particularly among low income and minority patients.

Methods

We performed a retrospective cohort study of outpatients with heart failure and diabetes in the New York City Health and Hospitals Corporation, the largest municipal health care system in the United States. Cox proportional hazard models were used to measure the association between HbA1c levels and outcomes of all-cause hospitalization, heart failure hospitalization, and mortality.

Results

Of 4723 patients with heart failure and diabetes, 42.6 % were black, 30.5 % were Hispanic/Latino, 31.4 % were Medicaid beneficiaries and 22.9 % were uninsured. As compared to patients with an HbA1c of 8.0–8.9 %, patients with an HbA1c of <6.5, 6.5–6.9, 7.0–7.9, and ≥9.0 % had an adjusted hazard ratio (aHR) (95 % CI) for all-cause hospitalization of 1.03 (0.90–1.17), 1.05 (0.91–1.22), 1.03 (0.90–1.17), and 1.13 (1.00–1.28), respectively. An HbA1c ≥ 9.0 % was also associated with an increased risk of heart failure hospitalization (aHR 1.33; 95 % CI 1.11–1.59) and a non-significant increased risk in mortality (aHR 1.20; 95 % CI 0.99–1.45) when compared to HbA1c of 8.0–8.9 %.

Conclusions

Among a cohort of primarily minority and low income patients with heart failure and diabetes, an increased risk of hospitalization was observed only for an HbA1c greater than 9 %.

Relationship between glycated albumin and glycated hemoglobin according to glucose tolerance status: A multicenter study

AIMS

To determine the relationship between glycated albumin (GA) and glycated hemoglobin (HbA1c) and to explore the association of glycated albumin/glycated hemoglobin (GA/HbA1c) ratio with glucose indices in Chinese subjects with varying glucose tolerance status.

METHODS

This hospital-based, cross-sectional study involved 953 participants without known diabetes from 11 centers in China. Oral glucose tolerance test (OGTT) was used to identify three groups of subjects: normal glucose regulation (n=194), impaired glucose regulation (n=303) and newly diagnosed type 2 diabetes group (n=456). The GA, HbA1c and GA/HbA1c ratio were tested.

RESULTS

GA was positively correlated with HbA1c (r=0.832, P<0.001). After correcting for age, sex and BMI, the correlations remained significant (r=0.824, P<0.001). Linear regression analysis estimated that a 1% increase of HbA1c was associated with a 2.84% increase of GA (GA=2.843×HbA1c-0.203; R(2)=0.692, P<0.001). GA would be 18.3 (16.7-19.9)% and 19.7 (18.0-21.4)% with HbA1c of 6.5% (48mmol/mol) and 7.0% (53mmol/mol). The mean GA/HbA1c ratio was 2.81±0.38, and it significantly increased with the presence of glucose intolerance (all, P<0.05). In the total study population, GA/HbA1c was correlated with BMI, glucose levels and 30-min insulin during OGTT, the homeostatic model assessment of β-cell function (HOMA-β), and ΔI30/ΔG30 (all, P<0.05). Increased glucose at 30min (standardized β=0.221, P<0.001), and decreased BMI (standardized β=-0.114, P=0.008) were associated with elevated GA/HbA1c ratio by multiple linear regression (adjusted R(2)=0.045).

CONCLUSIONS

The relationship between GA and HbA1c was strong. The GA/HbA1c ratio was related to acute postprandial glucose fluctuation and BMI level.

Decreased Glycemic Difference Between Diabetes and Nondiabetes in the Elderly Leads to the Reduced Diagnostic Accuracy of Hemoglobin A1c for Diabetes Screening in an Aged Chinese Population

BACKGROUND

This study investigated the impact of age on the accuracy of glycated hemoglobin (HbA1c) for diabetes screening and explored the possible cause(s).

MATERIALS AND METHODS

Data from 3,050 Chinese participants 25-75 years of age without known diabetes in a population-based cross-sectional survey were analyzed. Diabetes was diagnosed by the oral glucose tolerance test (OGTT). The performance of HbA1c for detecting OGTT-defined diabetes in tertile groups (divided by age) was evaluated by the area under the curve (AUC) of the receiver operating characteristic curve (ROC). The effect of age on the difference in glucose levels between participants with and without diabetes and the impact of this difference on the performance of HbA1c were evaluated.

RESULTS

In young (25-41 years old), middle-aged (41-53 years old), and old (55-72 years old) participants, the ROC AUC (95% confidence interval) of HbA1c for detecting OGTT-defined diabetes was 0.958 (0.915, 1.000), 0.891 (0.852, 0.930), and 0.861 (0.821, 0.901), respectively (P = 0.005). The difference of fasting plasma glucose between participants with diabetes and those without diabetes decreased with increasing age: 3.01 (2.80, 3.22) mmol/L, 2.90 (2.71, 3.09) mmol/L, and 2.33 (2.16, 2.50) mmol/L in the three consecutive age groups, respectively. A similar pattern was found in 2-h postprandial plasma glucose. The impact of age on the diagnostic power of HbA1c diminished after data were rearranged to artificially increase the difference between participants without diabetes and those with diabetes.

CONCLUSIONS

The accuracy of HbA1c for detecting OGTT-defined diabetes declines with age. This is largely due to the decreased separation in glycemic levels between participants with diabetes and without diabetes in the elderly.

Agreement of Point-of-Care Capillary Glycated Hemoglobin Levels with Conventional Screening Tests for Diabetes Mellitus in a Canadian First Nations Population

OBJECTIVES

1) How closely do capillary glycated hemoglobin (A1C) levels agree with venous A1C levels? 2) How well do venous A1C levels agree with plasma glucose for diagnosis of diabetes in this population?

METHODS

The Seabird Island mobile diabetes clinic screened people not known to have diabetes by using finger-prick capillary A1C levels with point-of-care analysis according to the Siemens/Bayer DCA 2000 system. Clients then went to a clinical laboratory for confirmatory testing for venous A1C levels, fasting plasma glucose (FPG) and plasma glucose 2 hours after 75 g oral glucose load (2hPG). A reference laboratory compared the DCA 2000 and the clinical laboratory's Roche Integra 800CTS system to the National Glycohemoglobin Standardization Program Diabetes Control and Complications Trial (DCCT) reference.

RESULTS

1) In the reference laboratory, DCA 2000 and Integra 800CTS both agreed very closely with the DCCT standard. In the field, capillary glycated hemoglobin percent (A1C) % was biased, underestimating venous A1C % by a mean of 0.19 (p<0.001). The margin of error of bias-adjusted capillary A1C % was ±0.36 for 95% of the time, compared to ±0.27 for venous A1C%. 2) By linear regression, we found FPG 7.0 mmol/L and 2hPG 11.1 mmol/L predicted mean venous A1C levels very close to 6.5%, with no significant bias.

CONCLUSIONS

Point-of-care capillary A1C did not perform as well in the field as in the laboratory, but the bias is correctible, and the margin of error is small enough that the test is clinically useful. In this population, venous A1C levels ≥6.5% agree closely with the FPG and 2hPG thresholds to diagnose diabetes; ethnic-specific adjustment of the venous A1C threshold is not necessary.

Superiority of lipoprotein particle number to detect associations with arterial thickness and stiffness in obese youth with and without prediabetes

BACKGROUND

The nuclear magnetic resonance (NMR) lipoprotein profile provides additional cardiovascular risk information beyond traditional lipids in high-risk adults. Similar studies have not been conducted in youth.

OBJECTIVE

To evaluate the relationship between the NMR profile and preclinical vascular measures in youth.

METHODS

We studied 96 obese youth with prediabetes (mean age = 18.1 ± 3.6 years, 63% female, 78% African American) and 118 obese normoglycemic controls (mean age = 18.0 ± 3.1 years, 75% female, 62% African American) cross sectionally. Traditional lipids (triglycerides, total, high-density lipoprotein [HDL], and low-density lipoprotein [LDL] cholesterol), NMR particle size (particle concentration [P] and size) and vascular thickness (carotid IMT) and stiffness (pulse wave velocity [PWV]) were measured. Independent associations between lipoproteins with carotid IMT and PWV after adjustment for group, age, race, sex, BMI z score, blood pressure, HOMA-IR, and A1c were studied.

RESULTS

NMR analysis revealed youth with prediabetes exhibited a more atherogenic profile with higher levels of small LDL-P and HDL-P and lower levels of intermediate and large HDL-P (P < .03). In addition, lower intermediate HDL-P was associated with a higher carotid IMT, whereas higher small HDL-P was associated with a higher PWV (P < .01). Traditional lipids were not significantly different between groups and were not associated with either vascular outcome.

CONCLUSIONS

NMR lipoprotein subclasses have improved sensitivity compared to traditional lipids to detect lipoprotein abnormalities in normoglycemic and prediabetic obese youth and are independently associated with preclinical vascular thickness and stiffness. NMR lipids may enhance cardiovascular risk assessment in youth.

Led Astray by Hemoglobin A1c: A Case of Misdiagnosis of Diabetes by Falsely Elevated Hemoglobin A1c

Hemoglobin A1c (A1c) is used frequently to diagnose and treat diabetes mellitus. Therefore, it is important be aware of factors that may interfere with the accuracy of A1c measurements. This is a case of a rare hemoglobin variant that falsely elevated a nondiabetic patient’s A1c level and led to a misdiagnosis of diabetes. A 67-year-old male presented to endocrine clinic for further management after he was diagnosed with diabetes based on an elevated A1c of 10.7%, which is approximately equivalent to an average blood glucose of 260 mg/dL. Multiple repeat A1c levels remained >10%, but his home fasting and random glucose monitoring ranged from 92 to 130 mg/dL. Hemoglobin electrophoresis and subsequent genetic analysis diagnosed the patient with hemoglobin Wayne, a rare hemoglobin variant. This variant falsely elevates A1c levels when A1c is measured using cation-exchange high-performance liquid chromatography. When the boronate affinity method was applied instead, the patient’s A1c level was actually 4.7%. Though hemoglobin Wayne is clinically silent, this patient was erroneously diagnosed with diabetes and started on an antiglycemic medication. Due to this misdiagnosis, the patient was at risk of escalation in his “diabetes management” and hypoglycemia. Therefore, it is important that providers are aware of factors that may result in hemoglobin A1c inaccuracy including hemoglobin variants.

Medication Adherence Does Not Explain Black-White Differences in Cardiometabolic Risk Factor Control among Insured Patients with Diabetes

BACKGROUND

Among patients with diabetes, racial differences in cardiometabolic risk factor control are common. The extent to which differences in medication adherence contribute to such disparities is not known. We examined whether medication adherence, controlling for treatment intensification, could explain differences in risk factor control between black and white patients with diabetes.

METHODS

We identified three cohorts of black and white patients treated with oral medications and who had poor risk factor control at baseline (2009): those with glycated hemoglobin (HbA1c) >8 % (n = 37,873), low-density lipoprotein cholesterol (LDL-C) >100 mg/dl (n = 27,954), and systolic blood pressure (SBP) >130 mm Hg (n = 63,641). Subjects included insured adults with diabetes who were receiving care in one of nine U.S. integrated health systems comprising the SUrveillance, PREvention, and ManagEment of Diabetes Mellitus (SUPREME-DM) consortium. Baseline and follow-up risk factor control, sociodemographic, and clinical characteristics were obtained from electronic health records. Pharmacy-dispensing data were used to estimate medication adherence (i.e., medication refill adherence [MRA]) and treatment intensification (i.e., dose increase or addition of new medication class) between baseline and follow-up. County-level income and educational attainment were estimated via geocoding. Logistic regression models were used to test the association between race and follow-up risk factor control. Models were specified with and without medication adherence to evaluate its role as a mediator.

RESULTS

We observed poorer medication adherence among black patients than white patients (p < 0.01): 50.6 % of blacks versus 39.7 % of whites were not highly adherent (i.e., MRA <80 %) to HbA1c oral medication(s); 58.4 % of blacks and 46.7 % of whites were not highly adherent to lipid medication(s); and 33.4 % of blacks and 23.7 % of whites were not highly adherent to BP medication(s). Across all cardiometabolic risk factors, blacks were significantly less likely to achieve control (p < 0.01): 41.5 % of blacks and 45.8 % of whites achieved HbA1c <8 %; 52.6 % of blacks and 60.8 % of whites achieved LDL-C <100; and 45.7 % of blacks and 53.6 % of whites achieved SBP <130. Adjusting for medication adherence/treatment intensification did not alter these patterns or model fit statistics.

CONCLUSIONS

Medication adherence failed to explain observed racial differences in the achievement of HbA1c, LDL-C, and SBP control among insured patients with diabetes.

Diagnostic values of glycated haemoglobin and diagnosis of diabetes: Results of a cross-sectional survey among general practitioners in the province of Reggio Emilia, Italy

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The multilevel analysis showed a strong GP clustering effect.

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The age was related to the likelihood to be diagnosed as ‘having diabetes’.

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Need to enhance dissemination on the use of HbA1c test as diagnostic tool.

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The exchange between GPs and the register could improve the diagnosis timeliness.

Aims

The aim of this study was to investigate whether subjects included in the diabetes register solely because their HbA1c was over the diagnostic threshold received a diagnosis of diabetes from their general practitioner (GP).

Methods

The study included all registered cases in 2009–2010 aged 18 or over that were identified only by the laboratory database because they had one or more HbA1c over the 6.5% threshold and for whom we did not find any information in the search of full electronic clinical records. Multilevel logistic regression was used to examine the influence of GP and patient characteristics.

Results

There were 228 participating GPs (76.3% of those invited) and 832 assessed subjects (68.8% of study population). There was a strong clustering among the GPs (residual intraclass correlation = 0.52, 95% CI 0.40–0.64). About one in two (55.5%) subjects with two or more HbA1c > =6.5% has been diagnosed as diabetic and the percentage declined – unless zeroing – in case the abnormal value was only one (28.3%). The likelihood of being labelled ‘no diabetes’ was greater in subjects aged less than 65 or over 74 with respect to the reference age group (OR 1.89, 95% CI 1.13–3.15; OR 1.55 95% CI 0.94–2.53). The same likelihood consistently decreased when HbA1c test was accompanied by abnormal fasting plasma glucose (FPG) assay (OR 0.20, 95% CI 0.12–0.32).

Conclusions

A permanent exchange of information between the diabetes register and GPs should be maintained to improve the care of patients and the awareness of criteria for diabetes diagnosis among GPs.

Standardising HbA1c-based diabetes diagnosis: opportunities and challenges

Globally, the incidence of diabetes mellitus is rising at an alarming rate and has become a health crisis that threatens the economies of all nations. Therefore, diagnosing diabetes has become an important issue in the management of diabetes. Glycated hemoglobin (HbA1c) is now recommended as a means to diagnose diabetes, but its use still has limitations. In this article, the biology, measurement, standardization, and opportunities and challenges of the use of HbA1c to diagnose diabetes are reviewed. More specifically, its use in China and the Asian region is discussed in detail.

Is There a Role for HbA1c in Pregnancy?

Outside pregnancy, HbA1c analysis is used for monitoring, screening for and diagnosing diabetes and prediabetes. During pregnancy, the role for HbA1c analysis is not yet established. Physiological changes lower HbA1c levels, and pregnancy-specific reference ranges may need to be recognised. Other factors that influence HbA1c are also important to consider, particularly since emerging data suggest that, in early pregnancy, HbA1c elevations close to the reference range may both identify women with underlying hyperglycaemia and be associated with adverse pregnancy outcomes. In later pregnancy, HbA1c analysis is less useful than an oral glucose tolerance test (OGTT) at detecting gestational diabetes. Postpartum, HbA1c analysis detects fewer women with abnormal glucose tolerance than an OGTT, but the ease of testing may improve follow-up rates and combining HbA1c analysis with fasting plasma glucose or waist circumference may improve detection rates. This article discusses the relevance of HbA1c testing at different stages of pregnancy.

Novel Risk Factors for Type 2 Diabetes in African-Americans

In the USA, compared to whites, African-Americans are disproportionately impacted by the diabetes epidemic. Traditional diabetes risk factors, such as obesity, are more common among African-Americans, but these traditional risk factors do not explain all of the disparity in diabetes risk. Recent research has identified novel environmental, lifestyle, physiologic, and genetic risk factors for diabetes, some of which appear to impact African-Americans more than whites. This manuscript reviews the recent literature to highlight some of these novel risk factors that may be contributing to the racial disparity in diabetes risk. Further study is needed of the modifiable risk factors for development of interventions to reduce the risk of diabetes in African-Americans, as well as other high-risk populations.

Performance of HbA1c for the prediction of diabetes in a rural community in Korea

AIM

To investigate the performance of HbA1c in predicting incident diabetes among Korean adults with normal fasting glucose and impaired fasting glucose levels.

METHODS

This study used data from the Korean Genome Epidemiology Study-Kangwha Study. A prospective analysis was carried out on 2079 people (820 men and 1259 women) who completed follow-up examinations up until 2013. Diabetes was defined as fasting blood glucose level ≥ 7.0 mmol/l, HbA1c level ≥ 48 mmol/mol (6.5%), or current treatment for diabetes. Areas under the receiver-operating characteristic curves were used to assess the different performances of HbA1c , glucose and insulin in predicting diabetes.

RESULTS

The median follow-up time was 3.97 years, during which 7.7% of men and 6.3% of women developed incident diabetes. The areas under the receiver-operating curves (95% CI) for diabetes prediction were 0.740 (0.692-0.787) for HbA1c , 0.716 (0.667-0.764) for glucose and 0.598 (0.549-0.648) for insulin. HbA1c showed better predictive power in people with impaired fasting glucose (area under the curve 0.753, 95% CI 0.685-0.821) than in those with normal glucose (area under the curve 0.648, 95% CI 0.577-0.719). An HbA1c threshold of 40 mmol/mol (5.8%) was found to have the highest predictive value for diabetes, with a relative risk of 6.30 (95% CI 3.49-11.35) in men and 3.52 (95% CI 2.06-6.03) in women after adjusting for age, waist circumference, triglycerides, hypertension, family history of diabetes, smoking, alcohol intake, exercise and baseline glucose level.

CONCLUSIONS

HbA1c can be used to identify people at high risk for the development of diabetes, especially in those with impaired fasting glucose levels.

Family Model of Diabetes Education With a Pacific Islander Community

PURPOSE

The purpose of the study was to use a community-based participatory research approach to pilot-test a family model of diabetes education conducted in participants' homes with extended family members.

METHODS

The pilot test included 6 families (27 participants) who took part in a family model of diabetes self-management education (DSME) using an intervention-driven pre- and posttest design with the aim of improving glycemic control as measured by A1C. Questionnaires and additional biometric data were also collected. Researchers systematically documented elements of feasibility using participant observations and research field reports.

RESULTS

More than three-fourths (78%) of participants were retained in the study. Posttest results indicated a 5% reduction in A1C across all participants and a 7% reduction among those with type 2 diabetes. Feasibility of an in-home model with extended family members was documented, along with observations and recommendations for further DSME adaptations related to blood glucose monitoring, physical activity, nutrition, and medication adherence.

CONCLUSIONS

The information gained from this pilot helps to bridge the gap between knowledge of an evidence-based intervention and its actual implementation within a unique minority population with especially high rates of type 2 diabetes and significant health disparities. Building on the emerging literature of family models of DSME, this study shows that the family model delivered in the home had high acceptance and that the intervention was more accessible for this hard-to-reach population.

Improving Detection of Prediabetes in Children and Adults: Using Combinations of Blood Glucose Tests

Highlights

Aim

To determine combinations of blood glucose tests: oral glucose tolerance (OGT), fasting plasma glucose (FPG), and hemoglobin A1C (HbA1C) that are associated with highest diagnostic rates of prediabetes in non-diabetic American children and adults.

Methods

The 2007–2008 U.S. National Health and Nutrition Examination Surveys data were used for this study. Overall and specific prevalence of prediabetes (defined using OGT + FPG, OGT + HbA1C, HbA1C + FPG, and OGT + FPG + HbA1C tests) were determined across age, race/ethnicity, sex, and BMI categories.

Results

FPG + HbA1C test was associated with significantly higher diagnostic rates of prediabetes across age, race/ethnicity, and BMI. Estimates of overall prevalence of prediabetes using OGT + FPG, OGT + HbA1C, HbA1C + FPG, and OGT + FPG + HbA1C tests were 20.3, 24.2, 33, and 34.3%, respectively. Compared to OGT + FPG, the use of HbA1C + FPG test in screening was associated with 44.8, 135, 38.6, and 35.9% increased prevalence of prediabetes in non-Hispanic White, non-Hispanic Black, Mexican-American, and other racial/ethnic men, respectively. The corresponding values in women were 67.8, 140, 37.2, and 42.6%, respectively. Combined use of all blood glucose tests did not improve the overall and gender-specific prediabetes prevalence beyond what was observed using HbA1C + FPG test.

Conclusion

HbA1C criteria were associated with higher diagnosis rates of prediabetes than FPG and OGT tests in non-diabetic American children and adults. Using a combination of HbA1C and FPG test in screening for prediabetes reduces intrinsic systematic bias in using just HbA1C testing and offers the benefits of each test. A well-defined HbA1C that takes into consideration race/ethnicity, gender, age, and body mass index may improve detection of prediabetes in population and clinical settings.

Epidemiology of Dysglycemia in Pregnant Oklahoma American Indian Women

CONTEXT

Minority communities are disproportionately affected by diabetes, and minority women are at an increased risk for glucose intolerance (dysglycemia) during pregnancy.

OBJECTIVES

In pregnant American Indian women, the objectives of the study were to use current criteria to estimate the prevalence of first-trimester (Tr1) dysglycemia and second-trimester (Tr2) incidence of gestational diabetes mellitus (GDM) and to explore new candidate measures and identify associated clinical factors.

DESIGN

This was a prospective cohort study. In Tr1 we performed a 75-g, 2-hour oral glucose tolerance test (OGTT) and glycated hemoglobin (HbA1c) to determine the following: fasting insulin; homeostasis model assessment of insulin resistance; serum 1,5-anhydroglucitol; noninvasive skin autofluorescence (SCOUT). We defined dysglycemia by American Diabetes Association and Endocrine Society criteria and as HbA1c of 5.7% or greater. In Tr2 in an available subset, we performed a repeat OGTT and SCOUT.

PARTICIPANTS

Pregnant American Indian women (n = 244 at Tr1; n = 114 at Tr2) participated in the study.

OUTCOMES

The prevalence of dysglycemia at Tr1 and incidence of GDM at Tr2 were measured.

RESULTS

At Tr1, one woman had overt diabetes; 36 (15%) had impaired glucose tolerance (American Diabetes Association criteria and/or abnormal HbA1c) and 59 (24%) had GDM-Tr1 (Endocrine Society criteria). Overall, 74 (30%) had some form of dysglycemia. Associated factors were body mass index, hypertension, waist/hip circumferences, SCOUT score, fasting insulin, and homeostasis model assessment of insulin resistance. At Tr2, 114 of the Tr1 cohort underwent a repeat OGTT and SCOUT, and 26 (23%) had GDM. GDM-Tr2 was associated with increased SCOUT scores (P = .029) and Tr1 body mass index, waist/hip circumferences, diastolic blood pressure, fasting insulin, and triglyceride levels. Overall, dysglycemia at Tr1 and/or Tr2 affected 38% of the women.

CONCLUSIONS

Dysglycemia at some point during pregnancy was common among American Indian women. It was associated with features of insulin resistance and may confer long-term health risks for mother and child.

Ethnic/racial determinants of glycemic markers in a UK sample

OBJECTIVE

To investigate possible causes for previously reported glycemia-independent South Asian-white differences in HbA1c.

METHODS

Demographic and laboratory data on non-diabetic patients from primary care were analyzed. Linear regression models measured the association between race/ethnicity and three glycemic measures (HbA1c, fructosamine and fasting plasma glucose), adjusted for a range of hematological, biochemical and demographic factors.

RESULTS

Nine hundred and forty-eight patients consisting of 711 white subjects (407 women) and 237 South Asian subjects (138 women) were studied. Unadjusted bivariate analysis showed that South Asians had higher HbA1c concentrations [41 (5.9 %) vs. 40 (5.8 %) mmol/mol (p = 0.011), coefficient 1.21, 95 % CI 0.27, 2.17 (p = 0.011)] similar fructosamine [228.4 vs. 226.7 mmol/L (p = 0.352), coefficient 3.93, 95 % CI 0.79, 7.08 (p = 0.014)] and fasting plasma glucose [5.1 vs. 5.2 mmol/L (p = 0.154), coefficient -0.09, 95 % CI -0.22, -0.04 (p = 0.156)] concentrations than whites. South Asians also had lower hemoglobin, ferritin and vitamin B12 concentrations than whites. After adjustment for independent variables, South Asian ethnicity was associated with higher HbA1c concentrations [0.89, 95 % CI 0.06-1.72 (p = 0.035)], higher fructosamine levels [3.93, 95 % CI 0.79, 7.08 (p = 0.014)] and lower fasting plasma glucose concentrations [-0.12, 95 % CI -0.26, -0.02 (p = 0.026)] compared to white race.

CONCLUSIONS

The increased prevalence of hematological abnormalities in South Asians and their higher adjusted HbA1c and fructosamine but lower fasting glucose levels compared to white subjects suggest that ethnic differences in glycation markers may, in part, be due to a combination of erythrocyte factors and glycemia-independent glycation.

The value of HbA1c for diagnosing type 2 diabetes mellitus between Chinese Uyghurs and Hans in Xinjiang

OBJECTIVE

To compare the difference of glycosylated hemoglobin (HbA1c) for diagnosing type 2 diabetes mellitus (T2DM) between Chinese Uyghurs and Hans in xinjiang.

METHODS

we collected 707 subjects, including 456 Uyghurs and 251 Hans in Xinjiang Kashi region. All the subjects were underwent oral glucose tolerance test (OGTT) for diagnosing T2DM, at the same time their clinical biochemical markers and HbA1c levels were also measured. Then the data were analyzed, the receiver operating characteristic (ROC) curve was plotted and correlation analysis were made by SPSS 19.0 software.

RESULTS

1. The levels of body mess index (BMI), 2-hour plasma glucose (2 h PG), diastolic blood pressure (DBP) total cholestero (TC) and triglycerides (TG) were 26.6±4.75 kg/m(2), 14.3±6.2 mmol/l, 81.6±13.4 mmHg, 4.5±1.3 mmol/l and 4.3±2.8 mmol/l in Uyghurs, moreover those were higher than Hans [25.4±13.3 kg/m(2), 13.1±6.9 mmol/l, 78.4±9.9 mmHg, 2.3±2.1 mmol/l and 2.0±1.4 mmol/l, (P<0.05)]. 2. Otherwise, the optimal cut-off value for HbA1c to diagnose T2DM was 6.95% in Uyghurs. At this cut-off value, the sensitivity, specificity, positive likelihood ratio (+LR), negative likelihood ratio (-LR) and the area under the ROC curve (AUC) were 98.3%, 97.7%, 43.64, 0.017 and 0.997. While the optimal cut-off value was 7.05% in Hans, and, the sensitivity, specificity, +LR, -LR and AUC separately were 91.1%, 92.8%, 0.971, 12.6, 0.096 and 0.971. 3. The correlation analysis was made in two populations. It demonstrated that HbA1c was positively correlated with BMI, TC and TG in Uyghurs (r=0.138, 0.273, 0.482, P<0.05). However, in Hans, the HbA1c only was positively correlated with TG (r=0.178, P<0.05).

CONCLUSION

The Uyghurs have higher metabolic markers, for example, BMI, TC, DBP and TG. It reveals that Uyghurs may have more severe insulin resistance (IR) comparing with Hans. And then, the cut-off value of HbA1c for diagnosing and screening T2DM is different between Uyghurs and Hans in Xinjiang.

Impact of ethnicity on progress of glycaemic control in 131,935 newly diagnosed patients with type 2 diabetes: a nationwide observational study from the Swedish National Diabetes Register

OBJECTIVES

Studies on ethnic disparities in glycaemic control have been contradictory, and compromised by excessively broad categories of ethnicity and inadequate adjustment for socioeconomic differences. We aimed to study the effect of ethnicity on glycaemic control in a large cohort of patients with type 2 diabetes.

SETTING

We used nationwide data (mainly from primary care) from the Swedish National Diabetes Register (2002-2011) to identify patients with newly diagnosed (within 12 months) type 2 diabetes.

PARTICIPANTS

We included 131,935 patients (with 713,495 appointments), representing 10 ethnic groups, who were followed up to 10 years.

PRIMARY AND SECONDARY OUTCOME MEASURES

Progress of glycated haemoglobin (HbA1c) for up to 10 years was examined. Mixed models were used to correlate ethnicity with HbA1c (mmol/mol). The effect of glycaemic disparities was examined by assessing the risk of developing albuminuria. The impact of ethnicity was compared to that of income, education and physical activity.

RESULTS

Immigrants, particularly those of non-Western origin, received glucose-lowering therapy earlier, had 30% more appointments but displayed poorer glycaemic control (2-5 mmol/mol higher HbA1c than native Swedes). Probability of therapy failure was 28-111% higher for non-Western groups than for native Swedes. High-income Western groups remained below the target-level of HbA1c for 4-5 years, whereas non-Western populations never reached the target level. These disparities translated into 51-92% higher risk of developing albuminuria. The impact of ethnicity was greater than the effect of income and education, and equal to the effect of physical activity.

CONCLUSIONS

Despite earlier pharmacological treatment and more frequent appointments, immigrants of non-Western origin display poorer glycaemic control and this is mirrored in a higher risk of developing albuminuria.

Racial/Ethnic Differences in Insulin Resistance and Beta Cell Function: Relationship to Racial Disparities in Type 2 Diabetes among African Americans versus Caucasians

Both biological and sociocultural factors have been implicated in the well-documented racial disparity in incidence and prevalence of type 2 diabetes (T2D) between African Americans (AA) and non-Hispanic whites (NHW). This review examines the extent to which biological differences in glucose metabolism, specifically insulin resistance and beta cell function (BCF), contribute to this disparity. The majority of available data suggests that AA are more insulin resistant and have upregulated BCF compared to NHW. Increasing evidence implicates high insulin secretion as a cause rather than consequence of T2D; therefore, upregulated BCF in AA may specifically confer increased risk of T2D in this cohort. Racial disparities in the metabolic characteristics of T2D have direct implications for the treatment and health consequences of this disease; therefore, future research is needed to determine whether strategies to reduce insulin secretion in AA may prevent or delay T2D and lessen racial health disparities.

Optimal Hemoglobin A1c Levels for Screening of Diabetes and Prediabetes in the Japanese Population

The aim of this study was to evaluate the utility of hemoglobin A1c (HbA1c) to identify individuals with diabetes and prediabetes in the Japanese population. A total of 1372 individuals without known diabetes were selected for this study. A 75 g oral glucose tolerance test (OGTT) was used to diagnose diabetes and prediabetes. The ability of HbA1c to detect diabetes and prediabetes was investigated using receiver operating characteristic (ROC) analysis. The kappa (κ) coefficient was used to test the agreement between HbA1c categorization and OGTT-based diagnosis. ROC analysis demonstrated that HbA1c was a good test to identify diabetes and prediabetes, with areas under the curve of 0.918 and 0.714, respectively. Optimal HbA1c cutoffs for diagnosing diabetes and prediabetes were 6.0% (sensitivity 83.7%, specificity 87.6%) and 5.7% (sensitivity 60.6%, specificity 72.1%), respectively, although the cutoff for prediabetes showed low accuracy (67.6%) and a high false-negative rate (39.4%). Agreement between HbA1c categorization and OGTT-based diagnosis was low in diabetes (κ = 0.399) and prediabetes (κ = 0.324). In Japanese subjects, the HbA1c cutoff of 6.0% had appropriate sensitivity and specificity for diabetes screening, whereas the cutoff of 5.7% had modest sensitivity and specificity in identifying prediabetes. Thus, HbA1c may be inadequate as a screening tool for prediabetes.

Association between Self-Reported Smoking and Hemoglobin A1c in a Korean Population without Diabetes: The 2011-2012 Korean National Health and Nutrition Examination Survey

Background

Several Western studies have revealed that among non-diabetics, glycosylated hemoglobin A1c (HbA1c) levels are higher in smokers than non-smokers. While studies conducted in Western populations consistently support this association, a recent meta-analysis reported that studies carried out in non-Western populations, including studies of Chinese, Egyptian, and Japanese-Americans, did not detect any significant differences in HbA1c levels between smokers and non-smokers.

Objectives

We assessed the association between smoking habits and HbA1c levels in the general Korean adult population using data from the Korean National Health and Nutrition Examination Survey (KNHANES) performed in 2011–2012.

Methods

A total of 10,241 participants (weighted n=33,946,561 including 16,769,320 men and 17,177,241 women) without diabetes were divided into four categories according to their smoking habits: never smokers (unweighted n/ weighted n= 6,349/19,105,564), ex-smokers (unweighted n/ weighted n= 1,912/6,207,144), current light smokers (<15 cigarettes per day, unweighted n/ weighted n=1,205/5,130,073), and current heavy smokers (≥15 cigarettes per day, unweighted n/ weighted n=775/3,503,781).

Results

In age- and gender-adjusted comparisons, the HbA1c levels of each group were 5.52 ± 0.01% in non-smokers, 5.49 ± 0.01% in ex-smokers, 5.53 ± 0.01% in light smokers, and 5.61 ± 0.02% in heavy smokers. HbA1c levels were significantly higher in light smokers than in ex-smokers (p = 0.033), and in heavy smokers compared with light smokers (p < 0.001). The significant differences remained after adjusting for age, gender, fasting plasma glucose, heavy alcohol drinking, hematocrit, college graduation, and waist circumference. Linear regression analyses for HbA1c using the above-mentioned variables as covariates revealed that a significant association between current smoking and HbA1c (coefficient 0.021, 95% CI 0.003–0.039, p = 0.019).

Conclusions

Current smoking was independently associated with higher HbA1c levels in a cigarette exposure-dependent manner in a representative population of Korean non-diabetic adults. In this study, we have observed an association between smoking status and HbA1c levels in non-diabetics drawn from a non-Western population, consistent with previous findings in Western populations.

Racial/ethnic disparities in prevalence and care of patients with type 2 diabetes mellitus

BACKGROUND

As of 2012, nearly 10% of Americans had diabetes mellitus. People with diabetes are at approximately double the risk of premature death compared with those in the same age groups without the condition. While the prevalence of diabetes has risen across all racial/ethnic groups over the past 30 years, rates are higher in minority populations. The objective of this review article is to evaluate the prevalence of diabetes and disease-related comorbidities as well as the primary endpoints of clinical studies assessing glucose-lowering treatments in African Americans, Hispanics, and Asians.

METHODS

As part of our examination of this topic, we reviewed epidemiologic and outcome publications. Additionally, we performed a comprehensive literature search of clinical trials that evaluated glucose-lowering drugs in racial minority populations. For race/ethnicity, we used the terms African American, African, Hispanic, and Asian. We searched PubMed for clinical trial results from 1996 to 2015 using these terms by drug class and specific drug. Search results were filtered qualitatively.

RESULTS

Overall, the majority of publications that fit our search criteria pertained to native Asian patient populations (i.e., Asian patients in Asian countries). Sulfonylureas; the α-glucosidase inhibitor, miglitol; the biguanide, metformin; and the thiazolidinedione, rosiglitazone have been evaluated in African American and Hispanic populations, as well as in Asians. The literature on other glucose-lowering drugs in non-white races/ethnicities is more limited.

CONCLUSIONS

Clinical data are needed for guiding diabetes treatment among racial minority populations. A multi-faceted approach, including vigilant screening in at-risk populations, aggressive treatment, and culturally sensitive patient education, could help reduce the burden of diabetes on minority populations. To ensure optimal outcomes, educational programs that integrate culturally relevant approaches should highlight the importance of risk-factor control in minority patients.

Association between the presence of iron deficiency anemia and hemoglobin A1c in Korean adults: the 2011-2012 Korea National Health and Nutrition Examination Survey

Few studies have investigated the clinical effect of iron deficiency anemia (IDA) on the use of the Hemoglobin A1c (HbA1c) as a screening parameter for diabetes or prediabetes. We investigated the association between IDA and HbA1c levels in Korean adults.Among the 11,472 adults (≥19 years of age) who participated in the 2011-2012 Korea National Health and Nutrition Examination Survey (a cross-sectional and nationally representative survey conducted by the Korean Center for Disease Control for Health Statistics), 807 patients with diabetes currently taking anti-diabetes medications were excluded from this study. We compared the weighted HbA1c levels and weighted proportion (%) of HbA1c levels of ≥5.7%, ≥6.1%, and ≥6.5% according to the range of fasting plasma glucose (FPG) levels and the presence of IDA.Among 10,665 participants (weighted n = 35,229,108), the prevalence of anemia and IDA was 7.3% and 4.3%, respectively. The HbA1c levels were higher in participants with IDA (5.70% ± 0.02%) than in normal participants (5.59% ± 0.01%; P < 0.001), whereas there was no significant difference in FPG levels. In participants with an FPG level of <100 mg/dL and 100 to 125 mg/dL, the weighted HbA1c level was higher in those with IDA (5.59% ± 0.02% and 6.00% ± 0.05%) than in normal participants (5.44% ± 0.01% and 5.82% ± 0.01%) after adjusting for confounders such as age, sex, FPG level, heavy alcohol drinking, waist circumference, and smoking status as well as after exclusion of an estimated glomerular filtration rate of <60 mL/min/1.73 m (P < 0.001, <0.01). The weighted proportions (%) of an HbA1c level of ≥5.7% and ≥6.1% were also higher in participants with IDA than in normal participants (P < 0.001, <0.05). However, the weighted HbA1c levels in individuals with an FPG level ≥126 mg/dL and a weighted proportion (%) of an HbA1c level of ≥6.5% showed no significant differences according to the presence of IDA.In conclusion, the presence of IDA shifted the HbA1c level upward only in the normoglycemic and prediabetic ranges, not in the diabetic range. Therefore, IDA should be considered before using HbA1c as a screening test for prediabetes.

Awareness of Prediabetes and Diabetes among Persons with Clinical Depression

Background. Major depressive disorder (MDD) is highly comorbid with diabetes, a relationship underappreciated by clinicians. Purpose. Examine the proportion of nonpregnant individuals ≥20 years with MDD and elevated glucose and the demographic and clinical characteristics associated with unrecognized elevated glucose. Methods. 14,373 subjects who participated in the National Health and Nutrition Examination Survey (2007-2012) completed the PHQ-9 depression screen and had hemoglobin A1C (HbA1c) measured. PHQ-9 scores ≥10 and HbA1c scores ≥5.7% were defined as MDD and elevated HbA1c, respectively. Data were analyzed using complex survey sampling software. Results. 38.4% of the sample with MDD had elevated HbA1c readings. Compared with nondepressed subjects, they were significantly more likely to have elevated glucose readings (P = 0.003) and to be aware of their elevated glucose levels if they had a higher body mass index, family history of diabetes, more doctor visits in the past year, a usual care source, health insurance, or were taking hypertension or hypercholesterolemia medications. Conclusions. Many adults with MDD have elevated HbA1c levels, have never been advised of elevated HbA1c, have not received diabetes screening, and have minimal contact with a healthcare provider. Additional opportunities for diabetes risk screening in people with MDD are needed.

Unfavorable inflammatory profile in adults at risk of type 2 diabetes identified by hemoglobin A1c levels according to the American Diabetes Association criteria

AIMS

We aimed to evaluate the inflammatory profile of individuals with prediabetes defined by HbA1c levels, according to the new American Diabetes Association criteria, and to determine the ability of HbA1c to identify individuals with subclinical inflammation independently of the contribution of other metabolic parameters such as fasting, 1- or 2-h post-load glucose (PG) levels.

METHODS

High sensitivity C-reactive protein (hsCRP), erythrocyte sedimentation rate (ESR), fibrinogen, white blood cells (WBC) count and complement C3 (C3) were assessed, and oral glucose tolerance test (OGTT) was performed in 711 adults.

RESULTS

Subjects were stratified into three groups according to their HbA1c levels. Poor agreement existed between HbA1c and 2-h PG criteria for identification of individuals with prediabetes (κ coefficient = 0.300). As compared with subjects having HbA1c <5.7 % (39 mmol/mol), individuals with prediabetes (HbA1c 5.7-6.4 %, [39-46 mmol/mol]) exhibited a significant increase of the concentration of five inflammatory markers (hsCRP, ESR, fibrinogen, WBC count, C3) as well as of a cluster of inflammatory markers, as measured by an inflammatory score after adjusting for sex, age, smoking, fasting, 1- and 2-h PG levels. In multiple regression models including sex, age, body mass index, smoking habit, fasting, 1- and 2-h PG levels, and HOMA index, HbA1c levels were significant independent contributors to each of the five inflammatory markers examined.

CONCLUSIONS

These data suggest that HbA1c is a reliable marker of glucose homeostasis, and may identify individuals at increased risk of diabetes with unfavorable inflammatory profile independently from fasting and 2-h PG levels.

The discordance between HbA1c and glucose tolerance testing for the postpartum exclusion of diabetes following gestational diabetes

AIMS

To assess the concordance between the HbA1c and the oral glucose tolerance test (OGTT) for the diagnosis of diabetes and prediabetes following gestational diabetes (GDM) in an ethnically diverse population.

METHODS

Women with GDM underwent a concurrent OGTT and HbA1c test 6-12 weeks postpartum.

RESULTS

There were 114 women with GDM who had a 75 g 2-h OGTT and HbA1c at 9.0 ± 3.2 weeks postpartum. Five subjects had diabetes using OGTT criteria, and 4 by HbA1c criteria. No subjects had diabetes on both criteria. The overall concordance between the OGTT and HbA1c for the diagnosis of diabetes, prediabetes, or normal glucose tolerance was only 54% (κ coefficient 0.058, p=0.41). Gravidity, the 2-h glucose level on the OGTT during pregnancy, and the 3rd trimester HbA1c predicted discordance between the postpartum OGTT and HbA1c.

CONCLUSIONS

There is poor concordance between the OGTT and HbA1c for the diagnosis of diabetes and prediabetes following GDM. This reflects that the two tests measure different aspects of dysglycemia. In the post-GDM population, the HbA1c misses cases of diabetes as identified by the OGTT. We recommend that the OGTT be retained for postpartum diabetes testing following GDM.

Effect of chronic kidney disease on A1C in individuals being screened for diabetes

OBJECTIVE

Glycated haemoglobin (A1C) has been recommended for the diagnosis of type 2 diabetes mellitus. Chronic kidney disease (CKD) is reported to increase A1C. The prevalence of CKD and its association with A1C as a diagnostic test for type 2 diabetes screening in a community population was studied.

RESEARCH DESIGN AND METHODS

Age, gender, ethnicity (white/South Asian), haemoglobin, A1C, fasting glucose and fructosamine were compared in participants with estimated glomerular filtration rate (eGFR) 30-59 (CKD 3) and ≥60 ml/min/1.73 m(2) using chi-squared or t-tests. Multivariable linear regression analyses were performed with A1C as the dependent variable; remaining variables were forced into a model to identify correlates with A1C. Data were parametric and expressed as means.

RESULTS

Of 949 participants 83.7% had eGFR ≥60, 16.3% had CKD 3 and only 2 had eGFR <30 (CKD ≥4). Compared with eGFR ≥60, patients with CKD 3 were older [p<0.001], had higher A1C [6.0% vs. 5.8%, p<0.001], fasting glucose [5.4 vs. 5.2m mol/L, p=0.003] and fructosamine [233.7 vs. 225.8μ mol/L, p<0.001] but lower haemoglobin [p=0.006]. After adjustment, gender and CKD stage were not associated with A1C. A1C was associated (p<0.05) positively with age, South Asian ethnicity, fasting glucose and fructosamine and inversely with haemoglobin levels.

CONCLUSIONS

Severe CKD (stage ≥4) is rare in primary care patients being screened for type 2 diabetes and its impact on A1C could not be evaluated. Although A1C is higher among patients with CKD stage 3 compared to those with eGFR ≥60, this appeared to be due to the confounding effect of other variables rather than the presence of CKD.

Racial-ethnic disparities in management and outcomes among children with type 1 diabetes

BACKGROUND AND OBJECTIVES

Previous research has documented racial/ethnic disparities in diabetes treatments and outcomes. It remains controversial whether these disparities result from differences in socioeconomic status (SES) or other factors. We examined racial/ethnic disparities in therapeutic modalities and diabetes outcomes among the large number of pediatric participants in the T1D Exchange Clinic Registry.

METHODS

The cohort included 10 704 participants aged <18 years with type 1 diabetes for ≥1 year (48% female; mean age: 11.9 ± 3.6 years; diabetes duration: 5.2 ± 3.5 years). Diabetes management and clinical outcomes were compared among 8841 non-Hispanic white (white) (83%), 697 non-Hispanic black (black) (7%), and 1166 Hispanic (11%) participants. The population included 214 high-income black and Hispanic families.

RESULTS

Insulin pump use was higher in white participants than in black or Hispanic participants (61% vs 26% and 39%, respectively) after adjusting for gender, age, diabetes duration, and SES (P < .001). Mean hemoglobin A1c was higher (adjusted P < .001) in black participants than in white or Hispanic participants (9.6%, 8.4%, and 8.7%). More black participants experienced diabetic ketoacidosis and severe hypoglycemic events in the previous year than white or Hispanic participants (both, P < .001). There were no significant differences in hemoglobin A1c, diabetic ketoacidosis, or severe hypoglycemia between white and Hispanic participants after adjustment for SES.

CONCLUSIONS

Even after SES adjustment, marked disparities in insulin treatment method and treatment outcomes existed between black versus Hispanic and white children within this large pediatric cohort. Barriers to insulin pump use and optimal glycemic control beyond SES should be explored in all ethnic groups.

Association of visit-to-visit variability of hemoglobin A1c and medication adherence

BACKGROUND

Medication nonadherence is widespread, but there are few efficient means of detecting medication nonadherence at the point of care. Visit-to-visit variability in clinical biomarkers has shown inconsistent efficiency to predict medication adherence.

OBJECTIVE

To examine the performance of visit-to-visit variability (VVV) of hemoglobin A1c to predict nonadherence to antidiabetic medications.

METHODS

In this cross-sectional study using a clinical and administrative database, adult members of a managed care plan at a safety-net medical center from 2008 to 2012 were included if they had ≥ 3 noninsulin antidiabetic prescription fills within the same class and ≥ 3 A1c measurements between the first and last prescription fills. The independent variable was VVV of A1c (within-subject standard deviation of A1c), and the dependent variable was medication adherence (defined by medication possession ratio) determined from pharmacy claims. Unadjusted and adjusted multivariate logistic regression models were created to examine the relationship between VVV of A1c and medication nonadherence. Receiver-operating characteristic (ROC) curves assessed the performance of the adjusted model at discriminating adherence from nonadherence.

RESULTS

Among 632 eligible subjects, mean A1c was 7.7% ± 1.3%, and 83% of the sample was nonadherent to antidiabetic medications. Increasing quintiles of VVV of A1c and medication nonadherence were both associated with increased within-subject mean A1c and younger subject age. The logistic regression model (adjusted for age, sex, race/ethnicity, within-subject mean A1c, number of A1c measurements, number of days between the first and last antidiabetic medication prescription fills, and rate of primary care visits during the study period) showed a nonsignificant association of VVV of A1c and medication nonadherence (OR = 1.19, 95% CI = 0.42-3.38 for the highest quintile of VVV). Adding VVV of A1c to a model including age, sex, and race only modestly improved the C-statistic of the ROC curve from 0.6786 to 0.7064.

CONCLUSIONS

VVV of A1c is not a robust predictor of antidiabetic medication nonadherence. Further innovation is needed to develop novel methods of detecting nonadherence.

Racial disparities in outcomes following PEA and asystole in-hospital cardiac arrests

AIM

To define the racial differences present after PEA and asystolic IHCA and explore factors that could contribute to this disparity.

METHODS

We analyzed PEA and asystolic IHCA in the Get-With-The-Guidelines-Resuscitation database. Multilevel conditional fixed effects logistic regression models were used to estimate the relationship between race and survival to discharge and return of spontaneous circulation (ROSC), sequentially controlling for hospital, patient demographics, comorbidities, arrest characteristic, process measures, and interventions in place at time of arrest.

RESULTS

Among the 561 hospitals, there were 76,835 patients who experienced IHCA with an initial rhythm of PEA or asystole (74.8% white, 25.2% black). Unadjusted ROSC rate was 55.1% for white patients and 54.1% for black patients (unadjusted OR: 0.94 [95% CI, 0.90-0.98], p=0.016). Survival to discharge was 12.8% for white patients and 10.4% for black patients (unadjusted OR: 0.83 [95% CI, 0.78-0.87], p<0.001). After adjusting for temporal trends, patient characteristics, hospital, and arrest characteristics, there remained a difference in survival to discharge (OR: 0.85 [95% CI, 0.79-0.92]) and rate of ROSC (OR: 0.88 [95% CI, 0.84-0.92]). Black patients had a worse mental status at discharge after survival. Rates of DNAR placed after survival from were lower in black patients with a rate of 38.3% compared to 44.5% in white patients (p<0.001).

CONCLUSION

Black patients are less likely to experience ROSC and survival to discharge after PEA or asystole IHCA. Individual patient characteristics, event characteristics, and hospital characteristics don't fully explain this disparity. It is possible that disease burden and end-of-life preferences contribute to the racial disparity.

comparative study of glucose homeostasis, lipids and lipoproteins, HDL functionality, and cardiometabolic parameters in modestly severely obese African Americans and White Americans with prediabetes: implications for the metabolic paradoxes

OBJECTIVE

To determine whether modestly severe obesity modifies glucose homeostasis, levels of cardiometabolic markers, and HDL function in African Americans (AAs) and white Americans (WAs) with prediabetes.

RESEARCH DESIGN AND METHODS

We studied 145 subjects with prediabetes (N = 61 WAs, N = 84 AAs, mean age 46.5 ± 11.2 years, mean BMI 37.8 ± 6.3 kg/m(2)). We measured fasting levels of lipids, lipoproteins, and an inflammatory marker (C-reactive protein [CRP]); HDL functionality (i.e., levels of paraoxonase 1 [PON1]); and levels of oxidized LDL, adiponectin, and interleukin-6 (IL-6). We measured serum levels of glucose, insulin, and C-peptide during an oral glucose tolerance test. Values for insulin sensitivity index (Si), glucose effectiveness index (Sg), glucose effectiveness at zero insulin (GEZI), and acute insulin response to glucose (AIRg) were derived using a frequently sampled intravenous glucose tolerance test (using MINMOD software).

RESULTS

Mean levels of fasting and incremental serum glucose, insulin, and C-peptide tended to be higher in WAs versus AAs. The mean Si was not different in WAs versus AAs (2.6 ± 2.3 vs. 2.9 ± 3.0 × 10(-4) × min(-1) [μU/mL](-1)). Mean values for AIRg and disposition index as well as Sg and GEZI were lower in WAs than AAs. WAs had higher serum triglyceride levels than AAs (116.1 ± 55.5 vs. 82.7 ± 44.2 mg/dL, P = 0.0002). Mean levels of apolipoprotein (apo) A1, HDL cholesterol, PON1, oxidized LDL, CRP, adiponectin, and IL-6 were not significantly different in obese AAs versus WAs with prediabetes.

CONCLUSIONS

Modestly severe obesity attenuated the ethnic differences in Si, but not in Sg and triglyceride levels in WAs and AAs with prediabetes. Despite the lower Si and PON1 values, AAs preserved paradoxical relationships between the Si and HDL/apoA1/triglyceride ratios. We conclude that modestly severe obesity has differential effects on the pathogenic mechanisms underlying glucose homeostasis and atherogenesis in obese AAs and WAs with prediabetes.

The optimal cutoff value of glycated hemoglobin for detection of diabetic retinopathy

With standardization of measurement of glycated hemoglobin (A1C), the International Expert Committee Report in 2009 and the American Diabetes Association in 2010 recommended incorporating A1C ≥6.5% into the previous diagnostic criteria using fasting plasma glucose and/or 2-hour plasma glucose. Whereas the association of A1C with cardiovascular diseases and other diabetic microvascular complications was linear without evidence of a distinct threshold, several studies suggested a threshold value for A1C in diabetic retinopathy (DR). In studies about the optimal cutoff value for A1C in DR, the A1C values range from 5.2% to 7.8%. There are several possible reasons why these values for DR differ so widely (differences in the definition and/or methods for DR, variation in statistical methods, differences in study population, differences in exclusion criteria, and difference in methods for measuring A1C). With these wide variations in the study method, drawing a conclusive cutoff value for A1C in DR is impossible. In published studies, the cutoff values for moderate or severe DR were higher than those for any or mild DR (6.4% to 7.0% vs. 5.5% to 6.5%).

Glycosylated hemoglobin testing in the National Social Life, Health, and Aging Project

OBJECTIVES

Longitudinal biomeasures of health are still new in nationally representative social science survey research. Data measuring blood sugar control provide opportunities for understanding the development of diabetes and its complications in older adults, but researchers must be aware that some of the differences across time can be due to variations in measurement procedures. This is a well-recognized issue whenever all samples cannot be assayed at the same time and we sought to present the analytic methods to quantify and adjust for the variation.

METHOD

We collected and analyzed HbA1C, glycated hemoglobin, a biomeasure of average blood sugar concentrations within the past few months. Improvements were made in the collection protocol for Wave 2, and assays were performed by a different lab.

RESULTS

The HbA1C data obtained during Wave 1 and Wave 2 are consistent with the expected population distributions for differences by gender, age, race/ethnicity, and diabetes status. Age-adjusted mean HbA1C declined slightly from Wave 1 to Wave 2 by -0.19 (95% confidence interval [CI]: -0.27, -0.10), and the average longitudinal change was -0.12 (95% CI: -0.18, -0.06).

DISCUSSION

Collection of HbA1C in Wave 2 permits researchers to examine the relationship between HbA1C and new health and social measures added in Wave 2, and to identify factors related to the change in HbA1C. Changes in collection protocol and labs between waves may have yielded small systematic differences that require analysts to carefully interpret absolute HbA1C values. We recommend analytic methods for cross wave differences in HbA1C and steps to ensure cross wave comparability in future studies.

Trends in diabetes incidence among 7 million insured adults, 2006-2011: the SUPREME-DM project

An observational cohort analysis was conducted within the Surveillance, Prevention, and Management of Diabetes Mellitus (SUPREME-DM) DataLink, a consortium of 11 integrated health-care delivery systems with electronic health records in 10 US states. Among nearly 7 million adults aged 20 years or older, we estimated annual diabetes incidence per 1,000 persons overall and by age, sex, race/ethnicity, and body mass index. We identified 289,050 incident cases of diabetes. Age- and sex-adjusted population incidence was stable between 2006 and 2010, ranging from 10.3 per 1,000 adults (95% confidence interval (CI): 9.8, 10.7) to 11.3 per 1,000 adults (95% CI: 11.0, 11.7). Adjusted incidence was significantly higher in 2011 (11.5, 95% CI: 10.9, 12.0) than in the 2 years with the lowest incidence. A similar pattern was observed in most prespecified subgroups, but only the differences for persons who were not white were significant. In 2006, 56% of incident cases had a glycated hemoglobin (hemoglobin A1c) test as one of the pair of events identifying diabetes. By 2011, that number was 74%. In conclusion, overall diabetes incidence in this population did not significantly increase between 2006 and 2010, but increases in hemoglobin A1c testing may have contributed to rising diabetes incidence among nonwhites in 2011.

The efficacy and safety of canagliflozin across racial groups in patients with type 2 diabetes mellitus

OBJECTIVE

Canagliflozin, a sodium-glucose co-transporter 2 inhibitor, enhances urinary glucose excretion through an insulin-independent mode of action, and improves glycemic control in patients with type 2 diabetes mellitus (T2DM). This study assessed the efficacy and safety of canagliflozin across racial groups.

METHODS

The efficacy of canagliflozin 100 mg and 300 mg was evaluated by racial group using data pooled from four placebo-controlled phase 3 studies and two placebo-controlled sub-studies of a population of patients with inadequately controlled T2DM (N = 4158). Least-squares mean changes from baseline were calculated for hemoglobin A1c (HbA1c), systolic blood pressure (SBP), body weight (BW), cholesterol, and triglycerides. Safety/tolerability evaluation included reporting of general and prespecified adverse events (AEs).

RESULTS

A total of 75% of patients were White, 13% were Asian, 4% were Black/African American, and 8% were 'Other' (American Indian, Alaskan Native, mixed race, Native Hawaiian or other Pacific Islander, not reported, and unknown). Baseline demographics were similar for these groups. Dose-related reductions in HbA1c, BW, and SBP were observed with both canagliflozin doses in all racial groups. Canagliflozin was generally safe and well tolerated. Treatment with canagliflozin was associated with an increased rate of genital mycotic infections (GMIs) and urinary tract infections (UTIs) in all racial groups. GMIs were observed more often in Black/African American males and males from the 'Other' racial group, whereas UTIs and osmotic diuresis-related AEs were less common in Asians. Key study limitations include the high proportion of White patients compared with other racial groups and the fact that included studies were not powered to evaluate racial differences.

CONCLUSION

Canagliflozin was generally well tolerated and consistently associated with reductions in HbA1c, BW, and SBP in patients with T2DM independent of racial background. (ClinicalTrials.gov numbers: NCT01081834; NCT01106677; NCT01106625; NCT01106690; and NCT01032629.).

Diabetes Complications at Presentation and One Year by Glycated Haemoglobin at Diagnosis in a Multiethnic and Diverse Socioeconomic Population: Results from the South London Diabetes Study

Background. WHO's recommendation of HbA1c ≥ 48 mmol/mol (6.5%) as diagnostic for type 2 diabetes mellitus (T2DM) was adopted by three UK London boroughs in May 2012. The South London Diabetes (SOUL-D) study has recruited people with newly diagnosed T2DM since 2008. We compared participants diagnosed before May 2012 with HbA1c < 48 mmol/mol to those with diagnostic HbA1c ≥ 48 mmol/mol. Methods. A prospective cohort study of newly diagnosed T2DM participants from 96 primary care practices, comparing demographic and biomedical variables between those with diagnostic HbA1c < 48 mmol/mol or HbA1c ≥ 48 mmol/mol at recruitment and after one year. Results. Of 1488 participants, 22.8% had diagnostic HbA1c < 48 mmol/mol. They were older and more likely to be white (p < 0.05). At recruitment and one year, there were no between-group differences in the prevalence of diabetic complications, except that those diagnosed with HbA1c < 48 mmol/mol had more sensory neuropathy at recruitment (p = 0.039) and, at one year, had new myocardial infarction (p = 0.012) but less microalbuminuria (p = 0.012). Conclusions. Use of HbA1c ≥ 48 mmol/mol as the sole T2DM diagnostic criterion may miss almost a quarter of those previously diagnosed in South London yet HbA1c < 48 mmol/mol may not exclude clinically important diabetes.

HbA1c as a predictor of diabetes and as an outcome in the diabetes prevention program: a randomized clinical trial

OBJECTIVE

Glycated hemoglobin (HbA1c), a standard measure of chronic glycemia for managing diabetes, has been proposed to diagnose diabetes and identify people at risk. The Diabetes Prevention Program (DPP) was a 3.2-year randomized clinical trial of preventing type 2 diabetes with a 10-year follow-up study, the DPP Outcomes Study (DPPOS). We evaluated baseline HbA1c as a predictor of diabetes and determined the effects of treatments on diabetes defined by an HbA1c ≥6.5% (48 mmol/mol).

RESEARCH DESIGN AND METHODS

We randomized 3,234 nondiabetic adults at high risk of diabetes to placebo, metformin, or intensive lifestyle intervention and followed them for the development of diabetes as diagnosed by fasting plasma glucose (FPG) and 2-h postload glucose (2hPG) concentrations (1997 American Diabetes Association [ADA] criteria). HbA1c was measured but not used for study eligibility or outcomes. We now evaluate treatment effects in the 2,765 participants who did not have diabetes at baseline according to FPG, 2hPG, or HbA1c (2010 ADA criteria).

RESULTS

Baseline HbA1c predicted incident diabetes in all treatment groups. Diabetes incidence defined by HbA1c ≥6.5% was reduced by 44% by metformin and 49% by lifestyle during the DPP and by 38% by metformin and 29% by lifestyle throughout follow-up. Unlike the primary DPP and DPPOS findings based on glucose criteria, metformin and lifestyle were similarly effective in preventing diabetes defined by HbA1c.

CONCLUSIONS

HbA1c predicted incident diabetes. In contrast to the superiority of the lifestyle intervention on glucose-defined diabetes, metformin and lifestyle interventions had similar effects in preventing HbA1c-defined diabetes. The long-term implications for other health outcomes remain to be determined.

Role of HbA1c in post-partum screening of women with gestational diabetes mellitus

Aim

To compare the performance of HbA1c with established glucose criteria during an oral glucose tolerance test (OGTT) and to assess HbA1c as a screening test for undiagnosed diabetes and pre-diabetes after gestational diabetes mellitus (GDM).

Methods

Glucose homeostasis was re-evaluated 1–5 years after delivery in 140 women with previous GDM, by means of OGTT and simultaneous HbA1c measurement. Glucose tolerance was defined according to World Health Organisation criteria. HbA1c ≥6.5% (≥48 mmol/mol) was used for diabetes diagnosis and HbA1c ≥5.7% (≥39 mmol/mol) to define abnormal glucose homeostasis.

Results

HbA1c had low sensitivity (14.3%) and high specificity (99.1%) in diabetes diagnosis. Sensitivity and specificity of HbA1c to detect abnormal glucose tolerance were 29.5% and 95.2%, respectively. The consistency in classifying abnormal glucose tolerance between HbA1c and OGTT criteria was 59% (κ = 0.227) and the area under the receiver operating characteristic curve was 0.708. The combined use of HbA1c and fasting glucose criteria showed similar performance to that of fasting glucose criteria alone. The latter identified 63% of the women with pre-diabetes or diabetes in the study cohort. However, by lowering the cut-point of HbA1c to ≥5.0% (≥31 mmol/mol), an additional proportion (27%) with isolated post-glucose load hyperglycaemia was identified.

Conclusion

Proposed thresholds of HbA1c had low diagnostic sensitivity. Combined with a fasting glucose test, the performance was no better than with using a fasting glucose test alone. Combining a fasting glucose test with a lower HbA1c cut-point may be an alternative approach for selection of women for an OGTT.

•

We compare the performance of HbA1c with established glucose criteria during an oral glucose tolerance test (OGTT).

•

We also assess HbA1c as a screening test for undiagnosed diabetes and pre-diabetes after gestational diabetes mellitus.

•

Proposed thresholds of HbA1c had low diagnostic sensitivity relative to OGTT.

•

Combining HbA1c with a fasting glucose test the performance was no better than using a fasting glucose test alone.

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Combining a fasting glucose test with a lower HbA1c cut-point may be an option for selection of women for an OGTT.

An early pregnancy HbA1c ≥5.9% (41 mmol/mol) is optimal for detecting diabetes and identifies women at increased risk of adverse pregnancy outcomes

OBJECTIVE

Pregnant women with undiagnosed diabetes are a high-risk group that may benefit from early intervention. Extrapolating from nonpregnancy data, HbA1c ≥6.5% (48 mmol/mol) is recommended to define diabetes in pregnancy. Our aims were to determine the optimal HbA1c threshold for detecting diabetes in early pregnancy as defined by an early oral glucose tolerance test (OGTT) at <20 weeks' gestation and to examine pregnancy outcomes relating to this threshold.

RESEARCH DESIGN AND METHODS

During 2008-2010 in Christchurch, New Zealand, women were offered an HbA1c measurement with their first antenatal bloods. Pregnancy outcome data were collected. A subset completed an early OGTT, and HbA1c performance was assessed using World Health Organization criteria.

RESULTS

HbA1c was measured at a median 47 days' gestation in 16,122 women. Of those invited, 974/4,201 (23%) undertook an early OGTT. In this subset, HbA1c ≥5.9% (41 mmol/mol) captured all 15 cases of diabetes, 7 with HbA1c <6.5% (<48 mmol/mol). This HbA1c threshold was also 98.4% (95% CI 97-99.9%) specific for gestational diabetes mellitus (GDM) before 20 weeks (positive predictive value = 52.9%). In the total cohort, excluding women referred for GDM management, women with HbA1c of 5.9-6.4% (41-46 mmol/mol; n = 200) had poorer pregnancy outcomes than those with HbA1c <5.9% (<41 mmol/mol; n = 8,174): relative risk (95% CI) of major congenital anomaly was 2.67 (1.28-5.53), preeclampsia was 2.42 (1.34-4.38), shoulder dystocia was 2.47 (1.05-5.85), and perinatal death was 3.96 (1.54-10.16).

CONCLUSIONS

HbA1c measurements were readily performed in contrast to the low uptake of early OGTTs. HbA1c ≥5.9% (≥41 mmol/mol) identified all women with diabetes and a group at significantly increased risk of adverse pregnancy outcomes.

Performance of glycated haemoglobin (HbA1c) as a screening test for diabetes and impaired glucose tolerance (IGT) in a high risk population--the Brazilian Xavante Indians

AIMS

To examine the properties of HbA1c to detect diabetes and IGT in adult Brazilian Xavante Indians, a high risk population for diabetes.

METHODS

The survey was carried out between October 2010 and January 2012 and based on a 75 g oral glucose tolerance test (OGTT). Basal and 2h capillary glycaemia were measured by HemoCue Glucose 201+; HbA1c using an automated high-performance liquid chromatography analyzer (Tosoh G7).

RESULTS

630 individuals aged ≥ 20 years were examined and 80 had a previous diagnosis of diabetes. Sensitivity, specificity and accuracy for HbA1c ≥ 6.5% (≥ 48 mmol/mol) were 71.3%, 90.5% and 87.2%. The areas under the ROC curve (AUC) was 0.88 (95%CI: 0.83-0.93). To identify IGT, HbA1c values between 5.7% and 6.4% (39-47 mmol/mol) presented sensitivity, specificity and accuracy of 87.2%, 24.7% and 51.4%, with an AUC of 0.62 (95%CI: 0.57-0.67).

CONCLUSIONS

The ADA/WHO proposed cut-off of 6.5% (48 mmol/mol) for HbA1c was adequate to detect diabetes among the Xavante. However, the performance of the ADA proposed cut-off points for pre-diabetes, when used to detect IGT was inadequate and should not be recommended.

Prevalence of hemoglobin variants in a diabetic population at high risk of hemoglobinopathies and optimization of HbA1c monitoring by incorporating HPLC in the laboratory workup

BACKGROUND

In Tunisia, diabetes mellitus and hemoglobinopathies are major public health problems. Glycated hemoglobin (HbA1c) is recommended for long-term monitoring of diabetes mellitus, but the presence of hemoglobin variants may interfere with HbA1c measurement. The aim was to determine the prevalence of hemoglobin variants in Tunisian diabetics and optimize the monitoring of diabetics using HbA1c.

METHODS

The study enrolled 9,792 Tunisian diabetic patients. HbA1c was measured by cation-exchange high-pressure liquid chromatography (HPLC). All the chromatograms were analyzed for the presence of Hb variants.

RESULTS

We identified 228 cases (2.33%) of Hb variants with D-10 HPLC (Bio-Rad): 191 with HbA/S trait, 27 with HbA/C trait, and 10 hemoglobin variants with the mention 'Variant-Window' on the chromatograms and subsequently identified as HbA/S on Variant I HPLC (Bio-Rad). Thus, the prevalence of HbS was 2.05%. We did not find any homozygous variant. All HbA1c results were reported to the treating physician.

CONCLUSIONS

To evaluate glycated hemoglobin in populations with a high prevalence of hemoglobinopathies, we should use the HPLC method, which is easy, economical, and reliable. Based on an algorithm, hemoglobin variants visualized on HPLC should be reported to the physician to improve the management of patients.

Financial strain, inflammatory factors, and haemoglobin A1c levels in African American women

OBJECTIVE

Type 2 diabetes disproportionately affects African American women, a population exposed to high levels of stress, including financial strain (Centers for Disease Control & Prevention, 2011, http://www.cdc.gov/diabetes/pubs/pdf/ndfs_2011.pdf). We tested a mediational model in which chronic financial strain among African American women contributes to elevated serum inflammation markers, which, in turn, lead to increased haemoglobin A1C (HbA1c) levels and risk for type 2 diabetes.

METHODS

We assessed level of financial strain four times over a 10-year period and tested its effect on two serum inflammation markers, C-reactive protein (CRP) and soluble interleukin-6 receptor (sIL-6R) in year 11 of the study. We tested the inflammation markers as mediators in the association between chronic financial strain and HbA1c, an index of average blood glucose level over several months.

DESIGN

Data were from 312 non-diabetic African American women from the Family and Community Health Study (FACHS; Cutrona et al., 2000, J. Pers. Soc. Psychol., 79, 1088).

RESULTS

Chronic financial strain predicted circulating sIL-6R after controlling for age, BMI, health behaviours, and physical health measures. In turn, sIL-6R significantly predicted HbA1c levels. The path between chronic financial strain and HbA1c was significantly mediated by sIL-6R. Contrary to prediction, CRP was not predicted by chronic financial strain.

CONCLUSIONS

Results support the role of inflammatory factors in mediating the effects of psychosocial stressors on risk for type 2 diabetes. Findings have implications for interventions that boost economic security and foster effective coping as well as medical interventions that reduce serum inflammation to prevent the onset of type 2 diabetes.

Low positive predictive value of hemoglobin A1c for diagnosis of prediabetes in clinical practice

BACKGROUND

Positive predictive value (PPV) of hemoglobin A1c (HbA1c) for diagnosis of prediabetes in clinical practice has not been well studied.

METHODS

In a prospective study, patients diagnosed with prediabetes based on HbA1c (5.7%-6.4%) underwent a 75-g oral glucose tolerance test (OGTT) as the gold standard test to diagnose dysglycemia. Demographics, anthropometrics, comorbidity, concomitant prescription medications and biochemical data were collected.

RESULTS

We identified 66 patients with HbA1c-based prediabetes with a mean HbA1c of 6.00 ± 0.20%. However, based on the OGTT, 32 had normal glucose tolerance (NGT), 26 had prediabetes and 8 had diabetes yielding a PPV of HbA1c of 39.4%. In univariate analysis, the patients with the OGTT-based prediabetes administered more medications for associated medical problems compared with the NGT group (5.9 ± 2.2 versus 2.6 ± 1.8, P < 0.0001). After adjustment for baseline variables, the medication use remained significantly different between OGTT-based prediabetes and NGT groups (P = 0.041).

CONCLUSIONS

PPV of HbA1c for diagnosis of prediabetes in clinical setting is low. Patients with HbA1c of 5.7% to 6.4% should undergo OGTT to confirm diagnosis of dysglycemia.