Distribution of HbA(1c) levels for children and young adults in the U.S.: Third National Health and Nutrition Examination Survey

Associations of childhood BMI traits with blood pressure and glycated haemoglobin in 6-9-year-old Samoan children

INTRODUCTION

Prevalence and risk factors for elevated glycated haemoglobin (HbA1c) and blood pressure (BP) are poorly understood among Pacific children. We examined associations of HbA1c and BP in 6-9 year-olds with body mass index (BMI) at ages 2, 5, and BMI velocity between 2-9 years in Samoa.

METHODS

HbA1c (capillary blood) and BP were measured in n = 410 Samoan children who were part of an ongoing cohort study. Multilevel models predicted BMI trajectory characteristics. Generalized linear regressions assessed associations of childhood characteristics and BMI trajectories with HbA1c and BP treated as both continuous and categorical outcomes. Primary caregiver-reported childhood characteristics were used as covariates.

RESULTS

Overall, 12.90% (n = 53) of children had high HbA1c (≥5.7%) and 33.17% (n = 136) had elevated BP. BMI at 5-years and BMI velocity were positively associated with high HbA1c prevalence in males. A 1 kg/m2 per year higher velocity was associated with a 1.71 (95% CI: 1.07, 2.75) times higher prevalence of high HbA1c. In females, higher BMI at 5-years and greater BMI velocity were associated with higher BP at 6-9 years (95% CI: 1.12, 1.40, and 1.42, 2.74, respectively).

CONCLUSION

Monitoring childhood BMI trajectories may inform cardiometabolic disease screening and prevention efforts in this at-risk population.

Determination of Time in Range Associated With HbA1c ≤7% in a Prospective Cohort of Patients With Type 1 Diabetes Using Continuous Glucose Monitoring for Three Months

INTRODUCTION

Finding a goal of time in range (%TIR) that defines good glycemic control is necessary. Previous retrospective studies suggest good concordance between HbA1c ≤7% with a TIR >70%; however, the studies that included the largest number of patients used blood glucose measurement data with a follow-up time of less than 90 days. This study defined the TIR value that best discriminates HbA1c ≤7%.

METHODS

We performed a prospective study of diagnostic tests based on a cohort of patients with type 1 diabetes (T1D) treated with a hybrid closed loop (HCL) followed for three months. The ability of %TIR to distinguish patients with HbA1c ≤7% was evaluated through receiver operating characteristic curve analysis. We determined the %TIR cutoff point with the best operating characteristics.

RESULTS

A total of 118 patients were included (58.1% women, 47% overweight or obese, and 33% with high glycemic variability). A moderate negative correlation (R = -.54, P < .001) was found between %TIR and HbA1c. The discrimination ability was moderate, with an area under the curve of 0.7485 (95% confidence interval = 0.6608-0.8363). The cutoff point that best predicted HbA1c ≤7% was %TIR ≥75.5 (sensitivity 70%, specificity 67%). The findings were similar among those with a coefficient of variation (CV%) ≥36%.

CONCLUSIONS

Our data suggest that the %TIR adequately identifies patients with HbA1c ≤7%. A target of TIR ≥75%, rather than the currently recommended TIR ≥70%, may be a more suitable value for optimal glycemic control.

Distribution and determinants of glycosylated hemoglobin in adolescents - Results from a nationwide population-based survey in Germany

The role of glycosylated hemoglobin (HbA1c) in youth is largely unclear. The aims of this study are to investigate the distribution and potential determinants of HbA1c among a population-based sample of adolescents. The German Health Interview and Examination Survey for Children and Adolescents (KiGGS) Wave 2 includes a nationwide representative sample of 0-17-year-old participants. For this evaluation, data from a randomly selected subgroup aged 14-17 years and without diagnosed diabetes was included (n = 857). Percentile-based HbA1c values (measured at laboratory in whole blood samples by high performance liquid chromatography) were calculated to examine HbA1c distribution. Multivariable linear regression analyses were performed to investigate factors (age, sex, parental socioeconomic status, body mass index (BMI), birth weight, smoking, alcohol consumption, healthy food diversity, sport activity, oral contraceptive use) associated with HbA1c. The mean HbA1c level was 5.2% (minimum: 3.9%, P10: 4.8%, P50: 5.1%, P90: 5.5%, maximum: 6.7%). Overall, 2.8% of adolescents had an HbA1c value in the prediabetic range (5.7-6.4%) and 0.1% had an undiagnosed diabetes (≥6.5%). Multivariable regression analysis showed an inverse association of age with HbA1c (17 vs. 14 years: ß: -1.18; 95% CI -2.05, -0.31). Higher HbA1c values were observed for higher BMI-standard deviation scores (SDS) (ß: 0.24; 95% CI -0.04, 0.52) and smoking (ß: 0.73; 95% CI -0.12, 1.57), but these tendencies were non-significant. In sex-stratified analysis, smoking and birth weight were significantly associated with HbA1c in boys. Among adolescents without diagnosed diabetes in Germany, HbA1c values ranged from 3.9% to 6.7%. To ensure health in adulthood, the influence of determinants on HbA1c levels in younger age should be further investigated.

2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

6. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes-2024

The American Diabetes Association (ADA) "Standards of Care in Diabetes" includes the ADA's current clinical practice recommendations and is intended to provide the components of diabetes care, general treatment goals and guidelines, and tools to evaluate quality of care. Members of the ADA Professional Practice Committee, an interprofessional expert committee, are responsible for updating the Standards of Care annually, or more frequently as warranted. For a detailed description of ADA standards, statements, and reports, as well as the evidence-grading system for ADA's clinical practice recommendations and a full list of Professional Practice Committee members, please refer to Introduction and Methodology. Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Clinically significant macular edema in an underserved population: Association with demographic factors and hemoglobin A1c

SIGNIFICANCE

Suspected clinically significant macular edema (SCSME) from exudates differed among ethnic groups in our underserved population. African American and Asian subjects had higher prevalence than Hispanics and non-Hispanic Caucasians, from the same clinics. Men had higher prevalence than women. Highly elevated blood glucose was frequent and associated with SCSME.

PURPOSE

We investigated the association between the presence of SCSME from exudates and hemoglobin A1c (HbA1c), as well as demographic factors such as age, sex, and ethnic group. Our population was underserved diabetic patients from the same geographic locations. Ethnic groups were White Hispanic, non-Hispanic Caucasian, African American, and Asian, with a high proportion of underrepresented minorities.

METHODS

In a diabetic retinopathy screening study at four community clinics in Alameda County, California, nonmydriatic 45° color fundus images were collected from underserved diabetic subjects following the EyePACS imaging protocol. Images were analyzed for SCSME from exudates by two certified graders. Logistic regression assessed the association between SCSME from exudates and age, sex, ethnic group, and HbA1c.

RESULTS

Of 1997 subjects, 147 (7.36%) had SCSME from exudates. The mean ± standard deviation age was 53.4 ± 10.5 years. The mean ± standard deviation HbA1c level was 8.26 ± 2.04. Logistic regression analysis indicated a significant association between presence of SCSME from exudates and HbA1c levels (p<0.001), sex (p=0.027), and ethnicity (p=0.030). African Americans (odds ratio [OR], 1.63; 95% confidence interval [CI], 1.06 to 2.50; p=0.025) and Asians (OR, 1.63; 95% CI, 1.05 to 2.54; p=0.029) had a higher risk than Hispanics. After adjusting for ethnicity, sex, and age, the odds of developing SCSME from exudates increased by 26.5% with every 1% increase in HbA1c level (OR, 1.26; 95% CI, 1.18 to 1.36; p<0.001).

CONCLUSIONS

In our underserved population, many diabetic patients had very high HbA1c values. Ethnic background (African American > Asians > Hispanics), sex (male > female), and HbA1c level were strong indicators for identifying who is at increased risk of developing SCSME from exudates.

Dietary patterns of Indian school-aged children and associations with markers of chronic disease risk

There is an increasing burden of noncommunicable diseases (NCDs) in India which may be related to changing dietary patterns. We aimed to assess dietary patterns in children since they have time to change unhealthy patterns before NCDs develop. Participants were 665 children, 9-12 years old, born with low birth weight and 77 similarly aged normal birth weight controls. We collected data on sociodemography, anthropometry, body composition, and markers of risk for NCDs: grip strength, long jump, hemoglobin A1c (HbA1c). A food frequency questionnaire was used to collect dietary data from which dietary patterns were derived using principal component analysis (PCA). Fourteen food groups were included in the PCA analysis, resulting in three components: 'fruits and vegetables', 'protein', and 'sugar and fat'. Higher socioeconomic status and maternal education were associated with lower adherence to the fruit and vegetable pattern and higher adherence to the protein and sugar and fat patterns. Adherence to the fruits and vegetables pattern was associated with lower height-for-age, whereas the fat and sugar pattern was associated with higher indicators of body fat. In linear regression analyses adjusted for age, sex, religion, socioeconomic status, maternal education, and season of data collection, adherence to the 'fruits and vegetables' pattern was associated with lower grip strength, shorter long jump, and lower HbA1c. Adherence to the other patterns was not associated with NCD risk factors. Higher consumption of fruits and vegetables, achievable even by poorer families in the cohort, may lower HbA1c, a risk factor for diabetes.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

BACKGROUND

Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association for Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association.

CONTENT

Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (HbA1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of HbA1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed.

SUMMARY

The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

BACKGROUND

Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association of Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association.

CONTENT

Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (Hb A1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of Hb A1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed.

SUMMARY

The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Youth-Onset Type 2 Diabetes: The Epidemiology of an Awakening Epidemic

In this narrative review, we describe the epidemiology (prevalence, incidence, temporal trends, and projections) of type 2 diabetes among children and adolescents (<20 years), focusing on data from the U.S. and reporting global estimates where available. Secondarily, we discuss the clinical course of youth-onset type 2 diabetes, from prediabetes to complications and comorbidities, drawing comparisons with youth type 1 diabetes to highlight the aggressive course of this condition, which, only recently, has become recognized as a pediatric disease by health care providers. Finally, we end with an overview of emerging topics in type 2 diabetes research that have potential to inform strategies for effective preventive action at the community and individual levels.

Considering metformin as a second-line treatment for children and adolescents with prediabetes

Overweight and obesity affect approximately 1/3 of children in the United States and are risk factors for prediabetes and type 2 diabetes. Progression from prediabetes to diabetes carries substantial long-term health burdens, culminating in decreased life-expectancy. Earlier development of type 2 diabetes is associated with poorer prognoses, and children lose glycemic control more rapidly than adults. Metformin is approved by the USFDA for the treatment of type 2 diabetes in children, has limited toxicity, and may help prevent the development of type 2 diabetes. The more rapid disease progression in children and the safety of metformin suggests that initiation of metformin treatment to children with prediabetes who have not effectively responded to lifestyle changes may help prevent short- and long-term health damage resulting from prediabetic and diabetic dysglycemia.

Anthropometry, body composition, early growth and chronic disease risk factors among Zambian adolescents exposed or not to perinatal maternal HIV

Early life exposures and growth patterns may affect long-term risk of chronic non-communicable diseases (NCD). We followed up in adolescence two Zambian cohorts (n 322) recruited in infancy to investigate how two early exposures - maternal HIV exposure without HIV infection (HEU) and early growth profile - were associated with later anthropometry, body composition, blood lipids, Hb and HbA1c, blood pressure and grip strength. Although in analyses controlled for age and sex, HEU children were thinner, but not shorter, than HIV-unexposed, uninfected (HUU) children, with further control for socio-demographic factors, these differences were not significant. HEU children had higher HDL-cholesterol than HUU children and marginally lower HbA1c but no other biochemical or clinical differences. We identified three early growth profiles - adequate growth, declining and malnourished - which tracked into adolescence when differences in anthropometry and body fat were still seen. In adolescence, the early malnourished group, compared with the adequate group, had lower blood TAG and higher HDL, lower grip strength (difference: -1·87 kg, 95 % CI -3·47, -0·27; P = 0·02) and higher HbA1c (difference: 0·5 %, 95 % CI 0·2, 0·9; P = 0·005). Lower grip strength and higher HbA1c suggest the early malnourished children could be at increased risk of NCD in later life. Including early growth profile in analyses of HIV exposure reduced the associations between HIV and outcomes. The results suggest that perinatal HIV exposure may have no long-term effects unless accompanied by poor early growth. Reducing the risk of young child malnutrition may lessen children's risk of later NCD.

The Potential Diagnostic and Predictive Role of HbA1c in Diabetic, Septic Patients: A Retrospective Single-Center Study

Background

As diabetes mellitus is a major risk factor of sepsis, we aimed to evaluate the possible effects of diabetes mellitus and poor glycemic control on the diagnosis of sepsis.

Methods

In our retrospective study, we included diabetic, septic patients—in whom the diagnosis of sepsis was based on the systemic inflammatory response syndrome (SIRS) criteria (n = 112, SIRS group)—who had HbA1c levels measured either in the previous 30 days (n = 39, SIRS 30 d subgroup) or within 24 hours after their emergency department admission (n = 73, SIRS 24 h subgroup). We later selected those patients from the SIRS group, whose sequential organ failure assessment (SOFA) score was ≥2 (n = 55, SOFA group), and these patients were also divided based on the time of HbA1c measurement (n = 21, SOFA 30 d subgroup and n = 34, SOFA 24 h subgroup). We analyzed the relationship between laboratory parameters, length of hospital stay, and HbA1c.

Results

We found a significant positive correlation between glucose and HbA1c (p < 0.001, p < 0.001, respectively), significant negative correlations between white blood cell count (WBC) and glucose (p=0.01, p=0.02, respectively), WBC and HbA1c levels (p=0.001, p=0.02, respectively) in the SIRS 24 h and SOFA 24 h subgroups. Furthermore, there was a significant positive correlation between length of hospital stay and HbA1c in the SOFA 24 h subgroup (p=0.01). No significant correlations were found in the SIRS 30 d and SOFA 30 d subgroups.

Conclusion

Based on our results, normal WBC with elevated HbA1c might be considered a positive SIRS criterium in diabetic, SIRS 24 h patients. Besides this potential diagnostic role, HbA1c might also be an additional prognostic biomarker in diabetic, SOFA 24 h patients.

Sex-Specific Associations of Iron-Anemia Status With Hemoglobin A1C Levels Among Hispanics/Latinos Without Self-Reported Diabetes Mellitus: The Hispanic Community Health Study/Study of Latinos

OBJECTIVE

The objective of this study was to examine the sex-specific associations of mutually exclusive iron-anemia status categories with hemoglobin A1C (HbA1C) levels among U.S. Hispanics/Latinos without self-reported diabetes mellitus.

METHODS

Baseline cross-sectional data (7247 women and 4904 men without self-reported diabetes mellitus) from the Hispanic Community Health Study/Study of Latinos were analyzed. Per the American Diabetes Association's defined criteria, based on HbA1C levels, the participants were categorized as having normoglycemia, prediabetes, or probable diabetes mellitus. The iron-anemia status categories were as follows: no anemia and no iron deficiency (reference), iron deficiency, iron deficiency anemia (IDA), and non-iron deficiency anemia (non-IDA). Survey multinomial logistic regression models were used to examine the sex-specific associations of iron-anemia status with HbA1C levels after adjusting for sociodemographic, lifestyle, and clinical factors.

RESULTS

The age-standardized prevalence of iron-anemia status categories differed by sex. Compared with those with no anemia and no iron deficiency and normoglycemia, women with IDA had higher odds of having prediabetes (odds ratio [OR], 2.18; 95% CI, 1.64-2.89) and probable diabetes mellitus (OR, 3.59; 95% CI, 1.62-7.99) based on HbA1C levels; men with non-IDA had higher odds of having probable diabetes mellitus (OR, 2.97; 95% CI, 1.13-7.78) based on HbA1C levels. All other associations did not reach statistical significance.

CONCLUSION

Among U.S. Hispanics/Latinos without self-reported diabetes mellitus, the age-standardized prevalence of iron deficiency, IDA, and non-IDA is high and varies by sex. Women with IDA had higher odds of having prediabetes and probable diabetes mellitus, defined based on HbA1C levels. Men with non-IDA had higher odds of having probable diabetes mellitus, defined based on HbA1C levels. Iron-anemia status should be considered while interpreting elevated HbA1C levels among U.S. Hispanics/Latinos without self-reported diabetes mellitus.

HbA1c percentiles and the association between BMI, age, gender, puberty, and HbA1c levels in healthy German children and adolescents

OBJECTIVE

The measurement of glycated hemoglobin (HbA1c) represents one way to detect type 1 and 2 diabetes in children at an early stage. However, to date, variations in HbA1c levels are not fully understood, even in healthy children. With this in mind, the present study aimed to establish HbA1c reference values in healthy children and to investigate the influence of various independent variables.

STUDY DESIGN AND METHODS

Two thousand four hundred fifty-five healthy children and adolescents aged between 0.5 and 18 years participated in the population-based cohort study LIFE Child, Germany. Age- and gender-dependent percentiles were estimated, enabling HbA1c values to be converted into standard deviation scores (SDS). Logistic regression models were applied to assess associations between HbA1c-SDS (as outcome) and age, gender, BMI, birth weight, physical activity, pubertal status, and socioeconomic status (SES; as explanatory variables).

RESULTS

The mean HbA1c value was 31.79 mmol/mol or 5.06% (SD = 3.3 mmol/mol, SD = 0.3%). Positive associations with HbA1c values were identified for age (b = 0.09, p < 0.001), gender (b = 0.25, p = 0.007), and BMI-SDS (b = 0.06, p < 0.001). In addition, obesity was related to higher HbA1c values (b = 0.29, p < 0.001). Compared to prepuberty, the pubertal and postpubertal stages were associated with higher HbA1c levels. Furthermore, higher SES was associated with higher HbA1c-SDS (b = 0.01, p = 0.04).

CONCLUSION

The present study established HbA1c reference values based on a large sample of healthy German children and adolescents. Age, gender, SES, pubertal stage, and BMI were found to be associated with higher HbA1c levels.

Hemoglobin A1c-Using Epidemiology to Guide Medical Practice: Kelly West Award Lecture 2020

The discovery that HbA1c was a valid and reliable measure of average glucose exposure was one of the most important advances in diabetes care. HbA1c was rapidly adopted for monitoring glucose control and is now recommended for the diagnosis of diabetes. HbA1c has several advantages over glucose. Glucose assessment requires fasting, has poor preanalytic stability, and is not standardized; concentrations are acutely altered by a number of factors; and measurement can vary depending on sample type (e.g., plasma or whole blood) and source (e.g., capillary, venous, interstitial). HbA1c does not require fasting, reflects chronic exposure to glucose over the past 2-3 months, and has low within-person variability, and assays are well standardized. One reason HbA1c is widely accepted as a prognostic and diagnostic biomarker is that epidemiologic studies have demonstrated robust links between HbA1c and complications, with stronger associations than those observed for usual measures of glucose. Clinical trials have also demonstrated that lowering HbA1c slows or prevents the development of microvascular disease. As with all laboratory tests, there are some clinical situations in which HbA1c is unreliable (e.g., certain hemoglobin variants, alterations in red blood cell turnover). Recent studies demonstrate that fructosamine and glycated albumin may be substituted as measures of hyperglycemia in these settings. Other approaches to monitoring glucose have recently been introduced, including continuous glucose monitoring, although this technology relies on interstitial glucose and epidemiologic evidence supporting its routine use has not yet been established for most clinical settings. In summary, a large body of epidemiologic evidence has convincingly established HbA1c as a cornerstone of modern diabetes care.

Obesity, putative biological mediators, and cognitive function in a national sample of children and adolescents

Childhood obesity has reached epidemic rates nationwide and may be associated with impaired cognitive function. A growing body of evidence suggests that poorer academic performance for children with obesity and overweight is related to declines in executive function skills. This study aimed to identify biological mediators between obesity and overweight and cognitive function among children and adolescents. A total of 3323 children aged 6-16 years from the Third National Health and Nutrition Examination Survey between 1988 and 1994 (NHANES III) was used to measure associations between measures of obesity and overweight, cognitive function (IQ test batteries), iron deficiency, inflammation (c-reactive protein), and glucose metabolism (glycosylated hemoglobin) using multiple mediation models. Approximately 15% of the children were overweight and 11% were obese. Results showed lower scores for children who were obese or overweight than children of normal weight on several IQ subtest batteries. Obesity and overweight were also associated with biological mediators such as iron deficiency, elevated c-reactive protein and glycosylated hemoglobin. Several biomarkers of iron status were also related to measures of cognitive function. Early declines in cognitive function are associated with biomarkers of iron deficiency and inflammation in children and adolescents, and while some biological linkages between obesity and overweight and cognitive function are identified herein, further study is needed to identify additional biological mediators between obesity and overweight and cognitive function in pediatric populations.

Relationships between HbA1c and continuous glucose monitoring metrics of glycaemic control and glucose variability in a large cohort of children and adolescents with type 1 diabetes

AIMS

To evaluate the relationships between HbA1c and Continuous Glucose Monitoring (CGM) metrics in children/adolescents with Type 1 Diabetes (T1D).

METHODS

HbA1c and real-life CGM data of the 12 weeks preceding its measurement were retrospectively collected from 654 children/adolescents with T1D. The relationships between HbA1c and CGM metrics were assessed by Spearman correlation coefficient. Participants were categorized into groups based on HbA1c and CGM metrics values. ANOVA was run across HbA1c and CGM metrics groups in the entire study population and in subjects stratified by CGM type, insulin therapy, age and puberty.

RESULTS

HbA1c was positively correlated with mean glucose, SD, %TAR > 180 mg/dL, %TAR > 250 mg/dL, HBGI and negatively with %TIR, %TBR and %time < 54 mg/dL. HbA1c-based groups were significantly associated with these metrics, but for each group their value widely ranged with a substantial overlap between them. HbA1c and HbA1c-based groups were not associated with %CV and LBGI, as well as %CV and LBGI-based groups had not significantly different HbA1c. Comparable results were found analysing subjects according to age, type of CGM, insulin therapy and puberty.

CONCLUSIONS

The relationships between HbA1c and CGM metrics described in this cohort of paediatric subjects with T1D support the importance of the evaluation of these metrics, in particular %CV and LBGI, independently of HbA1c value.

Puberty Is Associated with a Rising Hemoglobin A1c, Even in Youth with Normal Weight

Our objective was to explore the longitudinal trajectory of hemoglobin A1c (HbA1c) in well-characterized youth (n = 84) with normal weight and obesity during puberty. HbA1c rose from early puberty to Tanner stage 5, even in healthy, normal weight youth, revealing important implications for defining normal glycemia and prediabetes in adolescents.

Racial and Ethnic Differences in Metabolic Disease in Adolescents With Obesity and Polycystic Ovary Syndrome

Context

Polycystic ovary syndrome (PCOS) is common and associated with metabolic syndrome. In the general population, metabolic disease varies by race and ethnicity.

Objective

This work aimed to examine in depth the interaction of race and ethnicity with PCOS-related metabolic disease in adolescent youth.

Methods

A secondary analysis was conducted of data from girls (age 12-21 years) with overweight or obesity (> 90 body mass index [BMI] percentile) and PCOS. Measurements included fasting hormone and metabolic measures, a 2-hour oral glucose tolerance test (OGTT), and magnetic resonance imaging for hepatic fat. Groups were categorized by race or ethnicity.

Results

Participants included 39 non-Hispanic White (NHW, age 15.7 ± 0.2 years; BMI 97.7 ± 0.2 percentile), 50 Hispanic (HW, 15.2 ± 0.3 years; 97.9 ± 0.3 percentile), and 12 non-Hispanic Black (NHB, 16.0 ± 0.6 years; 98.6 ± 0.4 percentile) adolescents. Hepatic markers of insulin resistance were worse in NHW, including lower sex hormone-binding globulin and higher triglycerides over high-density lipoprotein cholesterol (TGs/HDL-C) ratio (P = .002 overall, HW vs NHB [P = .009] vs NHW [P = 0.020]), although homeostasis model assessment of estimated insulin resistance was worst in NHB (P = .010 overall, NHW vs NHB P = .014). Fasting and 2-hour OGTT glucose were not different between groups, although glycated hemoglobin A_1c (HbA_1c) was lowest in NHW (overall P < .001, NHW 5.2 ± 0.3 vs HW 5.5 ± 0.3 P < .001 vs 5.7 ± 0.4%, P < .001). The frequency of hepatic steatosis (HW 62%, NHW 42%, NHB 25%, P = .032); low HDL-C < 40 mg/dL (HW 82%, NHW 61%, NHB 50%, P < .001) and prediabetes HbA_1c 5.7% to 6.4% (NHB 50%, HW 36%, NHW 5%, P < .001) were different between the groups.

Conclusion

Adolescents with PCOS appear to show similar racial and ethnic variation to the general population in terms of metabolic disease components.

The Interaction between Hb A1C and Selected Genetic Factors in the African American Population in the USA

BACKGROUND

The global prevalence of diabetes mellitus has been growing in recent decades and the complications of longstanding type 2 diabetes continue to place a burden on healthcare systems. The hemoglobin A1c (Hb A1c) content of the blood is used to assess an individual's degree of glycemic control averaged over 2 to 3 months. In the USA, diabetes is the seventh leading cause of death. Black, indigenous, people of color (BIPOC) are disproportionately affected by diabetes compared to non-Hispanic whites. There are many reports of interaction of Hb A1c and hematologic conditions that have a high prevalence in the Black population; some of these effects are contradictory and not easily explained. This review attempts to document and categorize these apparently disparate effects and to assess any clinical impact.

METHODS

Hb A1C can be determined by a variety of techniques including cation-exchange chromatography, electrophoresis, immunoassays, and affinity chromatography. The amount of Hb A1c present in a patient specimen depends not only on blood glucose but is strongly influenced by erythrocyte survival and by structural variations in the globin chains. Sickling hemoglobinopathies are well-represented in the USA in African Americans and the effects of these hemoglobin disorders as well as G6PD deficiency is examined.

CONCLUSION

Hb A1c measurement should always be performed with a cautious approach. The laboratory scientist should be aware of possible pitfalls in unquestioningly determining Hb A1c without a consideration of hematologic factors, both inherited and acquired. This presents a challenge as often times, the laboratory is not aware of the patient's race.

The accuracy of provider diagnosed diabetes type in youth compared to an etiologic criteria in the SEARCH for Diabetes in Youth Study

BACKGROUND

Although surveillance for diabetes in youth relies on provider-assigned diabetes type from medical records, its accuracy compared to an etiologic definition is unknown.

METHODS

Using the SEARCH for Diabetes in Youth Registry, we evaluated the validity and accuracy of provider-assigned diabetes type abstracted from medical records against etiologic criteria that included the presence of diabetes autoantibodies (DAA) and insulin sensitivity. Youth who were incident for diabetes in 2002-2006, 2008, or 2012 and had complete data on key analysis variables were included (n = 4001, 85% provider diagnosed type 1). The etiologic definition for type 1 diabetes was ≥1 positive DAA titer(s) or negative DAA titers in the presence of insulin sensitivity and for type 2 diabetes was negative DAA titers in the presence of insulin resistance.

RESULTS

Provider diagnosed diabetes type correctly agreed with the etiologic definition of type for 89.9% of cases. Provider diagnosed type 1 diabetes was 96.9% sensitive, 82.8% specific, had a positive predictive value (PPV) of 97.0% and a negative predictive value (NPV) of 82.7%. Provider diagnosed type 2 diabetes was 82.8% sensitive, 96.9% specific, had a PPV and NPV of 82.7% and 97.0%, respectively.

CONCLUSION

Provider diagnosis of diabetes type agreed with etiologic criteria for 90% of the cases. While the sensitivity and PPV were high for youth with type 1 diabetes, the lower sensitivity and PPV for type 2 diabetes highlights the value of DAA testing and assessment of insulin sensitivity status to ensure estimates are not biased by misclassification.

The addition of spices and herbs to vegetables in the National School Lunch Program increased vegetable intake at an urban, economically-underserved, and predominantly African-American high school

Vegetable intake is far below recommendations among African-American adolescents living in economically-underserved urban areas. While the National School Lunch Program (NSLP) helps overcome access barriers, vegetable intake remains challenging and novel interventions are required. A two-year, multi-phase, school-based intervention was conducted at an urban, economically-underserved, and predominantly African-American high school in Baltimore, Maryland to determine whether stakeholder-informed addition of spices and herbs to NSLP vegetables would increase intake. The stakeholder engagement phase included assessment of NSLP vegetable attitudes/preferences among 43 school stakeholders and subsequent student sensory testing. The second phase was conducted in the school cafeteria and consisted of eight weeks comparing student intake of typical vegetable recipes versus otherwise-identical recipes with spices and herbs. 4,570 student lunch plates were included in the vegetable intake comparison. Vegetable intake was measured by lunch tray plate waste. Willingness to try vegetables was assessed by the difference between plate waste and estimated mean vegetable served weight. Intake of typical vegetable recipes and vegetable recipes with spices and herbs was compared with student's t-test. Chi-square test was used to compare willingness to try vegetables. Total vegetable intake was 18.2% higher (8.22 grams per meal, p<0.0001) with spices and herbs than with typical recipes. There were no differences in trying vegetables with spices and herbs, although student-led advocacy was associated with increased trying vegetables with spices and herbs (78.8% with advocacy, 67.5% without advocacy, p<0.0001). The addition of spices and herbs to vegetables in the NSLP was feasible and associated with small increases in vegetable intake at an urban, economically-underserved, and predominantly African-American high school.

Glycated haemoglobin as a screening test for abnormal glucose homeostasis in childhood obesity

AIM

To estimate the proportion of type 2 diabetes mellitus and abnormal glucose homeostasis in childhood obesity and assess the predictive role of HbA_1c as a diagnostic marker compared with oral glucose tolerance testing (OGTT).

METHODS

A retrospective study in a tertiary paediatric hospital. Data were collected on all overweight or obese children who underwent routine OGTT between 2012 and 2016. Ethnicity, anthropometry, comorbidities and other risk factors associated with diabetes were recorded systematically. Fasting venous glucose, insulin and HbA_1c values, along with 120-min venous glucose were recorded. Receiver operating characteristic (ROC) curve analysis was performed to derive optimum thresholds of HbA_1c for detection of type 2 diabetes, impaired fasting glucose (IFG) and impaired glucose tolerance (IGT). Predictive HbA_1c thresholds for the detection of abnormal glucose homeostasis in children with obesity were calculated.

RESULTS

Of 156 children, 13 (8%, 10 female, 10 Asian) had type 2 diabetes, 95 (61%) had normal glucose tolerance, 18 (12%) had isolated IFG, 19 (12%) had isolated IGT, and another 11 (7%) had both IFG and IGT. The proportion of abnormal glucose homeostasis was 39%. ROC curve analysis demonstrated that HbA_1c ≥ 42 mmol/mol (6.0%) predicted type 2 diabetes (specificity 95%, sensitivity 85%) but performed moderately for IFG (specificity 46%, sensitivity 78%) and IGT (specificity 78%, sensitivity 55%).

CONCLUSION

Despite HbA_1c being a less-sensitive diagnostic tool compared with OGTT for children with IFG and IGT, it is reliable in detecting type 2 diabetes in asymptomatic children with obesity, instead of the labour- and cost-intensive OGTT.

Distribution of glycated haemoglobin and its determinants in Indian young adults

AIM

The aim of the present study is to understand the distribution of A1c in four different age groups in young adults and its relation to other co-variants.

METHODS

The countrywide data was collected in 2017 in Individuals with high risk analysed by Indian Diabetes Risk Score (IDRS) and self-declared diabetics were identified after screening a sample of 240,968 individuals from rural (4 villages of about 500 adults each) and urban (4 census enumeration blocks of about 500 adults each) population spanning 65 districts of 29 states/UTs of Indian subcontinent. Blood tests and other detailed assessments were carried out on this selected group. This study presents the analysis of the A1c values of 2862 young adults (<35 years).

RESULTS

In the age group of 31-34 years, the proportion of Diabetes (22.36%) and Prediabetes (9.86%) was higher in comparison with younger age groups. Also, Diabetes (7.3%) and Prediabetes (22%) were highest among those who had parental history of DM in both parents as compared to those with Diabetes history in one parent [Diabetes (7.1%) or Prediabetes (19.0%)] and no Diabetes Parental History (Diabetes (7.3%) and Prediabetes (18.3%) cases. BMI was found to play a significant positive correlation with Diabetes and Prediabetes (p < 0.001) with range of A1c.

CONCLUSION

Age, BMI and parental history were found to be correlated with A1c levels in IDRS screened high-risk population. With increasing age, the proportion of Diabetics and Prediabetics also increased with positive correlation of age with A1c levels.

Association of Prenatal and Perinatal Exposures to Particulate Matter With Changes in Hemoglobin A1c Levels in Children Aged 4 to 6 Years

IMPORTANCE

Environmental risk factors for childhood type 2 diabetes, an increasing global problem, are understudied. Air pollution exposure has been reported to be a risk factor for this condition.

OBJECTIVE

To examine the association between prenatal and perinatal exposures to fine particulate matter with a diameter less than 2.5 μm (PM2.5) and changes in hemoglobin A1c (HbA1c), a measure of glycated hemoglobin and marker of glucose dysregulation, in children aged 4 to 7 years.

DESIGN, SETTING, AND PARTICIPANTS

The Programming Research in Obesity, Growth, Environment, and Social Stressors (PROGRESS) study, a birth cohort study conducted in Mexico City, Mexico, recruited pregnant women from July 3, 2007, to February 21, 2011, through public health maternity clinics. The present analysis includes 365 mother-child pairs followed up until the child was approximately 7 years of age. This study included data from only study visits at approximately 4 to 5 years (visit 1) and 6 to 7 years (visit 2) post partum because HbA1c levels were not measured in earlier visits. The data were analyzed from March 11, 2018, to May 3, 2019.

EXPOSURES

Daily PM2.5 exposure estimates at participants' home addresses from 4 weeks prior to mothers' date of last menstrual period (LMP), a marker of the beginning of pregnancy, to 12 weeks after the due date. Exposure was estimated from satellite measurements and calibrated against ground PM2.5 measurements, land use, and meteorological variables.

MAIN OUTCOMES AND MEASURES

Outcomes included HbA1c levels at 4 to 5 years and 6 to 7 years of age, and the change in the level from the former age group to the latter.

RESULTS

The sample included 365 children, of whom 184 (50.4%) were girls. The mean (range) age of the children was 4.8 (4.0-6.4) years at visit 1, and 6.7 (6.0-9.7) years at visit 2. At the time of delivery, the mean (range) age of the mothers was 27.7 (18.3-44.4) years, with a mean (range) prepregnancy body mass index of 26.4 (18.5-43.5). The mean (SD) prenatal PM2.5 exposure (22.4 μg/m3 [2.7 μg/m3]) was associated with an annual increase in HbA1c levels of 0.25% (95% CI, 0.004%-0.50%) from age 4 to 5 years to 6 to 7 years compared with exposure at 12 μg/m3, the national regulatory standard in Mexico. Sex-specific effect estimates were statistically significant for girls (β = 0.21%; 95% CI, 0.10% to 0.32%) but not for boys (β = 0.31%; 95% CI, -0.09% to 0.72%). The statistically significant windows of exposure were from week 28 to 50.6 after the mother's LMP for the overall cohort and from week 11 to the end of the study period for girls. Lower HbA1c levels were observed at age 4 to 5 years in girls (β = -0.72%; 95% CI, -1.31% to -0.13%, exposure window from week 16 to 37.3) and boys (β = -0.98%; 95% CI, -1.70% to -0.26%, exposure window from the beginning of the study period to week 32.7), but no significant association was found in the overall cohort (β = -0.13%; 95% CI, -1.27% to 1.01%). There was no significant association between PM2.5 exposure and HbA1c level at age 6 to 7 years in any group.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that prenatal and perinatal exposures to PM2.5 are associated with changes in HbA1c, which are indicative of glucose dysregulation, in early childhood. Further research is needed because this finding may represent a risk factor for childhood or adolescent diabetes.

Association of first-trimester HbA1c levels with adverse pregnancy outcomes in different ethnic groups

AIM

To determine, in a multi-ethnic cohort, the association of first-trimester HbA1c levels with the development of pregnancy complications.

METHODS

A prospective study between April 2013-October 2016. Participants were stratified in five ethnic groups. Women had an HbA1c measurement added to their first antenatal bloods. Primary outcome was macrosomia and secondary outcomes included preeclampsia and large-for-gestational age (LGA). A multivariate logistic regression analysis was performed to adjust for potential confounders in determining the association between different HbA1c cut-off points and obstetric outcomes on each ethnic group.

RESULTS

1,882 pregnancies were included. Analysis was limited to the three main ethnic groups: Caucasian (54.3%), South-Central Asian (19%) and Latin-American (12.2%). There was no association between HbA1c levels and obstetric outcomes among Caucasians. In Latin-Americans, an HbA1c ≥ 5.8% (40 mmol/mol) was associated with higher risk of macrosomia, whereas an HbA1c ≥ 5.9% (41 mmol/mol) was associated with LGA. In South-Central Asian, an HbA1c ≥ 5.7% (39 mmol/mol) was associated with increased risk of macrosomia and a continuous graded relationship between HbA1c levels and preeclampsia and LGA was detected starting at HbA1c levels of 5.4% (36 mmol/mol).

CONCLUSION

First-trimester HbA1c levels perform as a suitable predictor of pregnancy complications in South-Central Asian and Latin-American women whereas in Caucasian no significant associations were found.

Discrepancies between Glycosylated Hemoglobin and Fasting Plasma Glucose for Diagnosing Impaired Fasting Glucose and Diabetes Mellitus in Korean Youth and Young Adults

BACKGROUND

Glycosylated hemoglobin (HbA1c) has been recommended as a diagnostic test for prediabetes and diabetes. Here, we evaluated the level of agreement between diagnoses based on fasting plasma glucose (FPG) versus HbA1c levels and determined optimal HbA1c cutoff values for these diseases in youth and young adults.

METHODS

The study included 7,332 subjects (n=4,129, aged 10 to 19 years in youth group; and n=3,203 aged 20 to 29 years in young adult group) from the 2011 to 2016 Korea National Health and Nutrition Examination Survey. Prediabetes and diabetes were defined as 100 to 125 mg/dL (impaired fasting glucose [IFG]) and ≥126 mg/dL for FPG (diabetes mellitus [DM] by FPG [DM_FPG]), and 5.7% to 6.4% and ≥6.5% for HbA1c, respectively.

RESULTS

In the youth group, 32.5% with IFG had an HbA1c level of 5.7% to 6.4%, and 72.2% with DM_FPG had an HbA1c ≥6.5%. In the young adult group, 27.5% with IFG had an HbA1c level of 5.7% to 6.4%, and 66.6% with DM_FPG had an HbA1c ≥6.5%. Kappa coefficients for agreement between the FPG and HbA1c results were 0.12 for the youth group and 0.19 for the young adult group. In receiver operating characteristic curve analysis, the optimal HbA1c cutoff for IFG and DM_FPG were 5.6% and 5.9% in youths and 5.5% and 5.8% in young adults, respectively.

CONCLUSION

Usefulness of HbA1c for diagnosis of IFG and DM_FPG in Koreans aged <30 years remains to be determined due to discrepancies between the results of glucose- and HbA1c-based tests. Additional testing might be warranted at lower HbA1c levels to detect IFG and DM_FPG in this age group.

Normative range of blood biochemical parameters in urban Indian school-going adolescents

Adolescence is the most critical phase of human growth that radically alters physiology of the body and wherein any inconsistency can lead to serious health consequences in adulthood. The timing and pace at which various developmental events occur during adolescence is highly diverse and thus results in a drastic change in blood biochemistry. Monitoring the physiological levels of various biochemical measures in ample number of individuals during adolescence can call up for an early intervention in managing metabolic diseases in adulthood. Today, only a couple of studies in different populations have investigated blood biochemistry in a small number of adolescents however, there is no comprehensive biochemical data available worldwide. In view, we performed a cross-sectional study in a sizeable group of 7,618 Indian adolescents (3,333 boys and 4,285 girls) aged between 11–17 years to inspect the distribution of values of common biochemical parameters that generally prevails during adolescence and we observed that various parameters considerably follow the reported values from different populations being 3.56–6.49mmol/L (fasting glucose), 10.60–199.48pmol/L (insulin), 0.21–3.22nmol/L (C–peptide), 3.85–6.25% (HbA₁c), 2.49–5.54mmol/L (total cholesterol), 1.16–3.69mmol/L (LDL), 0.78–1.85mmol/L (HDL), 0.33–2.24mmol/L (triglycerides), 3.56–11.45mmol/L (urea), 130.01–440.15μmol/L (uric acid) and 22.99–74.28μmol/L (creatinine). Barring LDL and triglycerides, all parameters differed significantly between boys and girls (p< 0.001). Highest difference was seen for uric acid (p = 1.3 x10^-187) followed by C–peptide (p = 6.6 x10^-89). Across all ages during adolescence, glycemic and nitrogen metabolites parameters varied markedly with gender. Amongst lipid parameters, only HDL levels were found to be significantly associated with gender following puberty (p< 0.001). All parameters except urea, differed considerably in obese and lean adolescents (p< 0.0001). The present study asserts that age, sex and BMI are the essential contributors to variability in blood biochemistry during adolescence. Our composite data on common blood biochemical measures will benefit future endeavors to define reference intervals in adolescents especially when the global availability is scarce.

Hemoglobin A1c Levels Are Slightly but Significantly Lower in Normoglycemic Subjects With the Hemoglobin E Phenotype

Hb mutations can alter the structure, behavior, stability, or quantity of the globin chain produced. Some Hb variants shorten the erythrocyte life span, resulting in physiologically lower hemoglobin A1c (HbA1c) levels. The hemoglobin E (HbE) phenotype involves a single-nucleotide polymorphism that reduces β-globin chain synthesis. We compared the HbA1c levels of subjects with normal Hb (HbAA; N=131) and HbE (N=148) phenotypes, examining potential hematological and biochemical factors contributing to differences in HbA1c levels. All had normal fasting plasma glucose (<5.6 mmol/L), AST, ALT, and creatinine levels. Mean±SD HbA1c levels differed between HbAA and HbE subjects: 5.5±0.3% and 5.3±0.3% (P<0.001) according to an immunoassay, and 5.5±0.3% and 5.3±0.3% (P<0.001) according to cation-exchange HPLC, respectively. In multiple logistic regression, only mean corpuscular volume (P<0.001) contributed to the difference in HbA1c levels between groups. Although a 0.2% difference in HbA1c is relatively small and unlikely to alter clinical decisions, epidemiologically, this can lead to misclassification of a significant proportion of the population, especially since the threshold of non-diabetes HbA1c (≤5.6%) falls very close to the HbA1c median of the general population.

Genetic Ancestry Markers and Difference in A1c Between African American and White in the Diabetes Prevention Program

PURPOSE

HbA1c levels are higher in blacks than non-Hispanic whites (NHWs). We investigated whether genetics could explain this difference in Diabetes Prevention Program (DPP) participants.

METHODS

We tested (i) genetic variants causing hemoglobinopathies, (ii) a genetic risk score (GRS) based on 60 variants associated with HbA1c from genome-wide association meta-analysis, and (iii) principal component (PC) factors that capture continental ancestry derived from genetic markers distributed across the genome.

RESULTS

Of 2658 eligible DPP participants, 537 (20%) self-identified as black and 1476 (56%) as NHW. Despite comparable fasting and 2-hour glucose levels, blacks had higher HbA1c (mean ± SD = 6.2 ± 0.6%) compared with NHWs (5.8 ± 0.4%; P < 0.001). In blacks, the genetic variant causing sickle cell trait was associated with higher HbA1c [β (SE) = +0.44 (0.08)%; P = 2.1 × 10-4]. The GRS was associated with HbA1c in both blacks and NHWs. Self-identified blacks were distributed along the first PC axis, as expected in mixed ancestry populations. The first PC explained 60% of the 0.4% difference in HbA1c between blacks and NHWs, whereas the sickle cell variant explained 16% and GRS explained 14%.

CONCLUSIONS

A large proportion of HbA1c difference between blacks and NHWs was associated with the first PC factor, suggesting that unidentified genetic markers influence HbA1c in blacks in addition to nongenetic factors.

Percentile curves for cardiometabolic disease markers in Canadian children and youth: a cross-sectional study

Background

The objective of this study to develop percentile curves for cardiometabolic disease markers in a population-based sample of Canadian children and youth.

Methods

The analysis used data from 6116 children and adolescents between 6 and 19 years of age who participated in the Canadian Health Measures Survey cycles 1 (2007/2009), 2 (2009/2011), and 3 (2012/2013). Total cholesterol, HDL cholesterol, and hemoglobin A1c levels as well as fasting levels of triglycerides, insulin, and homeostasis model assessment insulin resistance were measured using standardized procedures. Age- and sex-specific centiles for all markers were calculated using Cole and Green’s LMS method.

Results

With the exception of hemoglobin A1c, all markers showed age- and sex-related differences during childhood and adolescence.

Conclusions

We have developed centile curves for cardiometabolic disease markers in Canadian children and adolescents and demonstrated age and sex differences that should be considered when evaluating these markers in this age group.

The somatostatin-secreting pancreatic δ-cell in health and disease

The somatostatin-secreting δ-cells comprise ~5% of the cells of the pancreatic islets. The δ-cells have complex morphology and might interact with many more islet cells than suggested by their low numbers. δ-Cells contain ATP-sensitive potassium channels, which open at low levels of glucose but close when glucose is elevated. This closure initiates membrane depolarization and electrical activity and increased somatostatin secretion. Factors released by neighbouring α-cells or β-cells amplify the glucose-induced effects on somatostatin secretion from δ-cells, which act locally within the islets as paracrine or autocrine inhibitors of insulin, glucagon and somatostatin secretion. The effects of somatostatin are mediated by activation of somatostatin receptors coupled to the inhibitory G protein, which culminates in suppression of the electrical activity and exocytosis in α-cells and β-cells. Somatostatin secretion is perturbed in animal models of diabetes mellitus, which might explain the loss of appropriate hypoglycaemia-induced glucagon secretion, a defect that could be mitigated by somatostatin receptor 2 antagonists. Somatostatin antagonists or agents that suppress somatostatin secretion have been proposed as an adjunct to insulin therapy. In this Review, we summarize the cell physiology of somatostatin secretion, what might go wrong in diabetes mellitus and the therapeutic potential of agents targeting somatostatin secretion or action.

Impact of Genetic Determinants of HbA1c on Type 2 Diabetes Risk and Diagnosis

PURPOSE OF REVIEW

Glycated hemoglobin (A1c) is used to diagnose type 2 diabetes and monitor glycemic control. Specific genetic variants interfere with A1c and effects/frequencies of some variants vary by ancestry. In this review, we summarize findings from large trans-ethnic meta-analyses of genome-wide association studies (GWAS) of A1c and describe some variants influencing erythrocyte biology and interfering with A1c.

RECENT FINDINGS

Recent GWAS meta-analyses have revealed 60 loci associated with A1c in multi-ethnic populations. The main A1c genetic driver in African Americans is rs1050828 (G6PD). Some identified loci are located in/near genes known as monogenic causes of erythrocytic disorders (ANK1, SPTA1) or iron disorders (TMPRSS6, HFE). Uncommon genetic variants (not revealed by GWAS) that are known to cause hemoglobinopathies may also influence A1C levels, partly by interfering with laboratory assays. Specific genetic variants that have a large impact on A1c levels may influence clinical practice, especially in individuals of African descent. Efforts to reveal novel A1c loci should focus on increasing representation of GWAS in non-European ancestries, and on using better genome-wide coverage of uncommon variants that are specific to each population.

Serum Cotinine and Hemoglobin A1c Among a National Sample of Adolescents Without Known Diabetes

Introduction

National data suggest tobacco smoke is positively associated with higher glycated hemoglobin (HbA1c) among adults. Our objective was to examine the association between serum cotinine and HbA1c among adolescents without known diabetes.

Methods

We assessed adolescents 12-19 years old (N = 11550) who participated in the 1999-2012 National Health and Nutrition Examination Survey. We applied sampling weights while performing multiple linear regression analyses.

Results

The prevalence of serum cotinine indicative of no tobacco smoke exposure (TSE, <0.05 ng/mL) was 43.2%, passive TSE (0.05-2.99 ng/mL) was 38.9%, and active TSE (>3 ng/mL) was 17.9% in our sample. Mean (± standard error) HbA1c in participants with no TSE was 5.16% (±0.01), passive TSE was 5.16% (±0.01), and active TSE was 5.14% (±0.01). No differences in HbA1c were found between TSE groups including sex, age, race/ethnicity, education, income, and physical activity or the fully adjusted model with waist circumference. We found cotinine × sex (p = .01) and cotinine × age (p = .02) interactions. There was an association between cotinine and HbA1c for males but not females. Within males, participants with cotinine ≥3 ng/mL (5.26 ± 0.02) had higher mean HbA1c than those with cotinine 0.05-2.99 ng/mL and <0.05 ng/mL (both 5.20 ± 0.01, p ≤ .02). The negative association between age and HbA1c was stronger for participants with cotinine ≥3 ng/mL than participants with cotinine <0.05 ng/mL.

Conclusion

No linear association was found between HbA1c and serum cotinine in adolescents overall after adjusting for potential confounders. Differences between TSE groups were found in males. Future research in adolescents should examine chronic TSE over time to examine the potential for development of type 2 diabetes.

Implications

TSE has been associated with increased risk for the development of type 2 diabetes among adults. It is unclear if this relationship holds in adolescents. We examined the association between serum cotinine and HbA1c in adolescents without known diabetes who completed the 1999-2012 National Health and Nutrition Examination Survey. Although no association was found between serum cotinine and HbA1c overall while controlling for potential confounding factors, we observed interaction effects that are indicative of TSE influencing HbA1c differentially by sex and age. Reducing TSE in adolescents should be a priority for future tobacco control efforts.

Distribution of glycated haemoglobin and its determinants in Korean youth and young adults: a nationwide population-based study

The present study aimed to describe the distribution of and to investigate the factors associated with glycated haemoglobin (HbA1c) values in Korean youth (10–19 years old) and young adults (20–29 years old). Data from the Korea Health and Nutrition Examination Survey (2011–2015) were used. A total of 6,418 participants (male 3,140 [53.2%]) aged 10–29 years were included in the analysis. Percentiles of HbA1c were calculated and HbA1c values were compared according to age, sex, and associated factors. The mean HbA1c values (% [mmol/mol]) were 5.42 ± 0.01 (35.7 ± 0.1) for youths and 5.32 ± 0.01 (34.7 ± 0.1) for young adults (P < 0.001). Male participants showed significantly higher HbA1c level than females (P < 0.001). When age was grouped into 5-year intervals, HbA1c was the highest in those aged 10–14 years and the lowest in those aged 20–24 years. After controlling for confounding variables, the HbA1c values of youths and male participants were significantly higher than those of young adults and female participants. The present study provides nationally representative data on the distribution of HbA1c values in Korean youth and young adults. There were significant differences in the level of HbA1c according to age and sex.

Comparison of A1C to Oral Glucose Tolerance Test for the Diagnosis of Prediabetes in Overweight and Obese Youth

IN BRIEF This study reports performance of A1C against the oral glucose tolerance test (OGTT) in predicting prediabetes among overweight and obese African-American and Caribbean children. A retrospective chart review was completed for 230 children. Receiver operating characteristic curves were generated to find the predictive performances of different tests against the OGTT. A1C alone is a poor discriminator of prediabetes in our study population, with low sensitivity (70%) and specificity (48.8%). BMI z score, A1C, and homeostatic model assessment of insulin resistance are significant predictors of prediabetes and, when taken together, provide better discrimination for prediabetes.

Higher Pretransplantation Hemoglobin A1c Is Associated With Greater Risk of Posttransplant Diabetes Mellitus

Introduction

Posttransplantation diabetes mellitus (PTDM) is a common complication among kidney transplant recipients and is associated with a higher risk of cardiovascular events and poorer graft and patient survival. The association of pretransplantation hemoglobin A1c (HbA1c) with PTDM remains unclear. Identifying recipients at greatest risk for PTDM may help guide monitoring and treatment strategies to prevent or delay the onset of PTDM.

Methods

We analyzed data from 1499 nondiabetic primary kidney transplant recipients with available pretransplantation HbA1c values in the United States Renal Data System (USRDS) from 2005 to 2011. Recipients with pretransplantation diabetes diagnosis or HbA1c ≥ 6.5% were excluded. We assessed the association of pretransplantation HbA1c with PTDM using Cox proportional hazards models. Pretransplantation HbA1c level as a continuous variable was modeled using restricted cubic splines with knots at the 25th, 50th, and 75th percentiles. Based on results from this model, pretransplantation HbA1c was further modeled using a linear spline with a single knot at 5.4%.

Results

A total of 395 recipients (26.4%) developed PTDM over a median follow-up of 1.8 years. Pretransplantation HbA1c was not significantly associated with risk of PTDM below 5.4%, whereas each 1% higher HbA1c above 5.4% was associated with an adjusted hazard ratio of 1.84 (95% confidence interval = 1.28, 2.66; P for change in slope = 0.04).

Discussion

Higher pretransplantation HbA1c above 5.4% is independently associated with greater risk of PTDM among kidney transplant recipients. A continuous relationship between pretransplantation HbA1c and risk of PTDM suggests that increased risk starts at HbA1c levels well below current thresholds for prediabetes.

Prevalence of high HbA1c levels in Brazilian adolescents: The Study of Cardiovascular Risk in Adolescents

AIM

To evaluate the prevalence of elevated glycated haemoglobin (HbA1c) levels in a population of adolescents participating in the Study of Cardiovascular Risk in Adolescents.

METHODS

This is a school-based cross-sectional study based on a complex sample of adolescents 12-17years old representative at the national and macro-regional levels and for each Brazilian state capital. Blood was collected in schools and then evaluated in a single laboratory. HbA1c levels were considered elevated if ⩾5.7% (39mmol/mol) and were analyzed according to sex, age, macro-region, type of school, skin color, and nutritional status.

RESULTS

Data from 37,804 adolescents were analyzed. The mean level of HbA1c was 5.4% (95%CI 5.4-5.4) (36mmol/mol [95%CI 36-36]), and 20.5% (95%CI 19.1-22.0) of adolescents presented values ⩾5.7% (⩾39mmol/mol). Among males, 23.6% (95%CI 21.8-25.6) showed elevated HbA1c levels compared to 17.5% (95%CI 15.9-19.2) observed in females. The prevalence of elevated levels of HbA1c was higher in adolescents with black skin color (27.6%; 95%CI 23.2-32.4) vs. white skin color (16.9%; 95%CI 15.4-18.5), and higher in those who studied in public schools (21.6%; 95%CI 20.0-23.4) vs. private schools (16.7%; 95%CI 14.7-19.0). Among obese adolescents, 29.7% (95%CI 25.4-34.3) had elevated levels of HbA1c, compared to 19.3% (95%CI 18.0-20.7) in normal weight students and 19.7% (95%CI 17.1-22.6) in overweight adolescents.

CONCLUSIONS

Obese male adolescents of lower socioeconomic status had a higher prevalence of elevated HbA1c levels. Our findings highlight the importance of focusing on this high risk group for interventions to prevent diabetes.

Diagnostic performance of HbA1c for diabetes in Arab vs. European populations: a systematic review and meta-analysis

AIM

To examine differences in the performance of HbA_1c for diagnosing diabetes in Arabs compared with Europeans.

METHODS

The PubMed, Embase and Cochrane library databases were searched for records published between 1998 and 2015. Estimates of sensitivity, specificity and log diagnostic odds ratios for an HbA_1c cut-point of 48 mmol/mol (6.5%) were compared between Arabs and Europeans, using a bivariate linear mixed-model approach. For studies reporting multiple cut-points, population-specific summary receiver operating characteristic (SROC) curves were constructed. In addition, sensitivity, specificity and Youden Index were estimated for strata defined by HbA_1c cut-point and population type. Database searches yielded 1912 unique records; 618 full-text articles were reviewed. Fourteen studies met the inclusion criteria; hand-searching yielded three additional eligible studies. Three Arab (N = 2880) and 16 European populations (N = 49 127) were included in the analysis.

RESULTS

Summary sensitivity and specificity for a HbA_1c cut-point of 48 mmol/mol (6.5%) in both populations were 42% (33-51%), and 97% (95-98%). There was no difference in area under SROC curves between Arab and European populations (0.844 vs. 0.847; P = 0.867), suggesting no difference in HbA_1c diagnostic accuracy between populations. Multiple cut-point summary estimates stratified by population suggest that Arabs have lower sensitivity and higher specificity at a HbA_1c cut-point of 44 mmol/mol (6.2%) compared with European populations. Estimates also suggest similar test performance at cut-points of 44 mmol/mol (6.2%) and 48 mmol/mol (6.5%) for Arabs.

CONCLUSIONS

Given the low sensitivity of HbA_1c in the high-risk Arab American population, we recommend a combination of glucose-based and HbA_1c testing to ensure an accurate and timely diagnosis of diabetes.

Distribution of Glycated Haemoglobin According to Early-Life and Contemporary Characteristics in Adolescents and Adults without Diabetes: The 1982 and 1993 Pelotas Birth Cohorts

Aim

Glycated haemoglobin (HbA_1c), a marker of glucose control in individuals with diabetes mellitus, is also related with the incidence of cardiometabolic risk in populations free of disease. The aim of this study was to describe the distribution of HbA_1c levels according to early-life and contemporary factors in adolescents and adults without diabetes mellitus.

Methods

HbA_1c was measured in adults aged 30 years and adolescents aged 18 years who are participants in the 1982 and 1993 Pelotas Birth Cohorts, respectively. Bivariate and multivariate analyses were performed to describe the HbA_1c mean values according to early-life and contemporary characteristics collected prospectively since birth.

Results

The distribution of the HbA_1c was approximately normal in both cohorts, with a mean (SD) 5.10% (0.43) in the 1982 cohort, and 4.89% (0.50) in the 1993 cohort. HbA_1c mean levels were significantly higher in individuals self-reported as black/brown skin color compared to those self-reported as white in both cohorts. Parental history of diabetes was associated with higher HbA_1c mean in adults, while stunting at one year old presented an inverse relation with the outcome in adolescents. No other early and contemporary factors were associated with HbA_1c levels in adults or adolescents.

Conclusions

We found a consistent relationship between HbA_1c and skin color in both cohorts. Further research is needed to understand the role of genomic ancestry on levels of HbA_1c concentrations which may inform policies and preventive actions for diabetes mellitus and cardiometabolic risk.

Chronic disease outcomes after severe acute malnutrition in Malawian children (ChroSAM): a cohort study

BACKGROUND

Tackling severe acute malnutrition (SAM) is a global health priority. Heightened risk of non-communicable diseases (NCD) in children exposed to SAM at around 2 years of age is plausible in view of previously described consequences of other early nutritional insults. By applying developmental origins of health and disease (DOHaD) theory to this group, we aimed to explore the long-term effects of SAM.

METHODS

We followed up 352 Malawian children (median age 9·3 years) who were still alive following SAM inpatient treatment between July 12, 2006, and March 7, 2007, (median age 24 months) and compared them with 217 sibling controls and 184 age-and-sex matched community controls. Our outcomes of interest were anthropometry, body composition, lung function, physical capacity (hand grip, step test, and physical activity), and blood markers of NCD risk. For comparisons of all outcomes, we used multivariable linear regression, adjusted for age, sex, HIV status, and socioeconomic status. We also adjusted for puberty in the body composition regression model.

FINDINGS

Compared with controls, children who had survived SAM had lower height-for-age Z scores (adjusted difference vs community controls 0·4, 95% CI 0·6 to 0·2, p=0·001; adjusted difference vs sibling controls 0·2, 0·0 to 0·4, p=0·04), although they showed evidence of catch-up growth. These children also had shorter leg length (adjusted difference vs community controls 2·0 cm, 1·0 to 3·0, p<0·0001; adjusted difference vs sibling controls 1·4 cm, 0·5 to 2·3, p=0·002), smaller mid-upper arm circumference (adjusted difference vs community controls 5·6 mm, 1·9 to 9·4, p=0·001; adjusted difference vs sibling controls 5·7 mm, 2·3 to 9·1, p=0·02), calf circumference (adjusted difference vs community controls 0·49 cm, 0·1 to 0·9, p=0·01; adjusted difference vs sibling controls 0·62 cm, 0·2 to 1·0, p=0·001), and hip circumference (adjusted difference vs community controls 1·56 cm, 0·5 to 2·7, p=0·01; adjusted difference vs sibling controls 1·83 cm, 0·8 to 2·8, p<0·0001), and less lean mass (adjusted difference vs community controls -24·5, -43 to -5·5, p=0·01; adjusted difference vs sibling controls -11·5, -29 to -6, p=0·19) than did either sibling or community controls. Survivors of SAM had functional deficits consisting of weaker hand grip (adjusted difference vs community controls -1·7 kg, 95% CI -2·4 to -0·9, p<0·0001; adjusted difference vs sibling controls 1·01 kg, 0·3 to 1·7, p=0·005,)) and fewer minutes completed of an exercise test (sibling odds ratio [OR] 1·59, 95% CI 1·0 to 2·5, p=0·04; community OR 1·59, 95% CI 1·0 to 2·5, p=0·05). We did not detect significant differences between cases and controls in terms of lung function, lipid profile, glucose tolerance, glycated haemoglobin A1c, salivary cortisol, sitting height, and head circumference.

INTERPRETATION

Our results suggest that SAM has long-term adverse effects. Survivors show patterns of so-called thrifty growth, which is associated with future cardiovascular and metabolic disease. The evidence of catch-up growth and largely preserved cardiometabolic and pulmonary functions suggest the potential for near-full rehabilitation. Future follow-up should try to establish the effects of puberty and later dietary or social transitions on these parameters, as well as explore how best to optimise recovery and quality of life for survivors.

FUNDING

The Wellcome Trust.

Are There Clinical Implications of Racial Differences in HbA1c? A Difference, to Be a Difference, Must Make a Difference

Studies that have compared HbA1c levels by race have consistently demonstrated higher HbA1c levels in African Americans than in whites. These racial differences in HbA1c have not been explained by measured differences in glycemia, sociodemographic factors, clinical factors, access to care, or quality of care. Recently, a number of nonglycemic factors and several genetic polymorphisms that operate through nonglycemic mechanisms have been associated with HbA1c Their distributions across racial groups and their impact on hemoglobin glycation need to be systematically explored. Thus, on the basis of evidence for racial differences in HbA1c, current clinical guidelines from the American Diabetes Association state: "It is important to take…race/ethnicity…into consideration when using the A1C to diagnose diabetes." However, it is not clear from the guidelines how this recommendation might be actualized. So, the critical question is not whether racial differences in HbA1c exist between African Americans and whites; the important question is whether the observed differences in HbA1c level are clinically meaningful. Therefore, given the current controversy, we provide a Point-Counterpoint debate on this issue. In the preceding point narrative, Dr. Herman provides his argument that the failure to acknowledge that HbA1c might be a biased measure of average glycemia and an unwillingness to rigorously investigate this hypothesis will slow scientific progress and has the potential to do great harm. In the counterpoint narrative below, Dr. Selvin argues that there is no compelling evidence for racial differences in the validity of HbA1c as a measure of hyperglycemia and that race is a poor surrogate for differences in underlying causes of disease risk.-William T. CefaluEditor in Chief, Diabetes Care.

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.

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.

Quantification of renal steatosis in type II diabetes mellitus using dixon-based MRI

PURPOSE

To evaluate renal lipid content in subjects with and without type II diabetes mellitus (DM2) using Dixon-based magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This retrospective study was approved by the Institutional Review Board and compliant with the Health Insurance Portability and Accountability Act. Sixty-nine adults with or without DM2 (n = 29, n = 40) underwent 3T MRI of the abdomen using 3D multiecho Dixon gradient-echo acquisition and proton-density fat fraction (FF) reconstruction. FF values were recorded within segmented regions of interest in the kidneys and liver. The FF measurement error was estimated from the within-subject difference between the right and left kidneys using Bland-Altman analysis. Correlation between renal FF, hepatic FF, and body mass index (BMI) was evaluated. The association between renal FF and DM2 was evaluated by Wilcoxon rank sum test as well as by multivariate regression to correct for potential confounding effects of age, sex, BMI, creatinine, and hepatic FF. P < 0.05 was considered statistically significant.

RESULTS

Per-subject 95% limits of agreement of the renal FF measurement were [-3.26%, +3.22%]. BMI was significantly correlated with renal FF (r = 0.266, P = 0.027) and with liver FF (r = 0.344, P = 0.006). Correlation between renal and hepatic FF did not reach statistical significance (r = 0.215, P = 0.090). Median renal FF (±interquartile range) was 2.18% (±2.52%) in the DM2 cohort, significantly higher than 0.80% (±2.63%) in the non-DM2 cohort (P < 0.001). After correcting for potential confounders, the relationship between DM2 and renal FF remained statistically significant (P = 0.005).

CONCLUSION

Renal lipid content can be measured noninvasively using Dixon-based MRI and may be increased in subjects with DM2 compared to those without DM2. J. Magn. Reson. Imaging 2016;44:1312-1319.

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.

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.