A laboratory standpoint on the role of hemoglobin A1c for the diagnosis of diabetes in childhood: more doubts than certainties?

Evaluation of the hemoglobin a1c test in detecting pediatric prediabetes

Aim: The aim of this study is to evaluate the diagnostic performance of the hemoglobin a1c (Hba1c) test in pediatric prediabetes, and to determine the cut-off value for the pediatric age , to examine the relationship of the Hba1c test between glucose levels,. Materials and Methods: This study was carried out by retrospectively evaluating the data of 548 children. Prediabetes cases were determined by taking fasting and oral glucose tolerance test (OGTT) 2 hour (2h) glucose levels as a reference. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for Hba1c, fasting, and OGTT 2h glucose tests. The area under the curve (AUC) was calculated for each test by receiver-operating characteristic analysis. Results: Based on glucose values, 1.6% of individuals were assigned to the diabetes mellitus, 14.6% to prediabetes, and 83.8% to normoglycemia group. When 5.7 was used as the threshold value for Hba1c in prediabetes, the sensitivity was 31.3%, specificity was 87.8%, PPV was 30.9%, and NPV was 88.0%, AUC:0,686. The optimal cut-off value of Hba1c was determined as 5.35%. At this value, the sensitivity was calculated as 66.3% and the specificity as 61.4%. Conclusion: Although the use of adult HbA1c criteria for the diagnosis of prediabetes in the pediatric ages is controversial due to the differences between the results of OGTT and HbA1c-based tests, prediabetes screening is still important. HbA1c≥5.35 will be useful to follow up on children with prediabetes in terms of risk and to screen them with OGTT.

Pros and Cons of Current Diagnostic Tools for Risk-Based Screening of Prediabetes and Type 2 Diabetes in Children and Adolescents with Overweight or Obesity

It is still a matter of debate which is the most suitable diagnostic test for risk-based screening of prediabetes and type 2 diabetes (T2D) in children and adolescents with overweight or obesity. This review highlighted benefits and pitfalls of currently recommended screening tools (fasting plasma glucose [FPG], oral glucose tolerance test [OGTT], glycated hemoglobin A1c [HbA1c]). The greatest advantage of OGTT is the ability to detect people with impaired glucose tolerance, a subcategory at high risk of developing both T2D and cardiovascular disease. Important disadvantages are low reproducibility and inconvenience. FPG measurement is more practical, as it needs only one blood draw, although both OGTT and FPG require fasting. The reliability of HbA1c as a screening tool has been questioned, especially in children and adolescents, but its undeniable convenience can lead to increased adherence to screening. In contrast, it can be altered by several nonglycemic factors. Importantly, none of these tests have been validated in the pediatric population. Alternative tests have been recently proposed, including new OGTT-derived biomarkers and additional nonfasting glycemic markers. In conclusion, when choosing the most suitable test in clinical practice, advantages and disadvantages should be considered, as well as the possibility of performing different tests at once.

Use of large scale EHR data to evaluate A1c utilization among sickle cell disease patients

BACKGROUND

The glycated hemoglobin (A1c) test is not recommended for sickle cell disease (SCD) patients. We examine ordering patterns of diabetes-related tests for SCD patients to explore misutilization of tests among this underserved population.

METHODS

We used de-identified electronic health record (EHR) data in the Cerner Health Facts™ (HF) data warehouse to evaluate the frequency of A1c and fructosamine tests during 2010 to 2016, for 37,151 SCD patients from 393 healthcare facilities across the United States. After excluding facilities with no A1c data, we defined three groups of facilities based on the prevalence of SCD patients with A1c test(s): adherent facilities (no SCD patients with A1c test(s)), minor non-adherent facilities, major non-adherent facilities.

RESULTS

We determined that 11% of SCD patients (3927 patients) treated at 393 facilities in the US received orders for at least one A1c test. Of the 3927 SCD patients with an A1c test, only 89 patients (2.3%) received an order for a fructosamine test. At the minor non-adherent facilities, 5% of the SCD patients received an A1c test while 58% of the SCD patients at the least adherent facilities had at least one A1c test. Overall, the percent of A1c tests ordered for SCD patients between 2010 and 2016 remained similar.

CONCLUSIONS

Inappropriate A1c test orders among a sickle cell population is a significant quality gap. Interventions to advance adoption of professional recommendations that advocate for alternate tests, such as fructosamine, can guide clinicians in test selection to reduce this quality gap are discussed. The informatics strategy used in this work can inform other largescale analyses of lab test utilization using de-identified EHR data.

Who should return for an oral glucose tolerance test? A proposed clinical pathway based on retrospective analysis of 332 children

OBJECTIVES

Fasting plasma glucose or oral glucose tolerance test (OGTT) is the traditional diagnostic tool for type 2 diabetes (T2DM). However, fasting is required and implementation in all overweight/obese subjects is not practical. This study aimed to formulate a clinical pathway to stratify subjects according to their risk of abnormal OGTT.

METHODS

This retrospective study included patients with overweight or obesity who had undergone OGTT in a tertiary paediatric unit from 2012 to 2018. The optimal haemoglobin A1c (HbA1c) cutoff that predicts abnormal OGTT was evaluated. Other non-fasting parameters, in combination with this HbA1c cutoff, were also explored as predictors of abnormal OGTT.

RESULTS

Three hundred and thirty-two patients (boys: 54.2%, Chinese: 97.3%) were included for analysis, of which, 272 (81.9%) patients had normal OGTT while 60 (18.0%) patients had abnormal OGTT (prediabetes or T2DM). Optimal HbA1c predicting abnormal OGTT was 5.5% (AUC 0.71; sensitivity of 66.7% and specificity of 71%). When HbA1c≥5.5% was combined with positive family history and abnormal alanine transaminase (ALT) level, the positive predictive value for abnormal OGTT was increased from 33.6 to 61.6%.

CONCLUSIONS

HbA1c, family history of T2DM and ALT level could be used to derive a clinical pathway to stratify children who have high risk of abnormal OGTT.

Increased Levels of Glycated Hemoglobin A1c and Iron Deficiency Anemia: A Review

Worldwide, the prevalence of diabetes remains high. Studies have shown that iron deficiency anemia (IDA) is associated with increased levels of glycated hemoglobin A1c (HbA1c), but the mechanism remains unclear. Hematological changes, iron metabolism, study methodology, and other factors could affect the results of diagnostic investigations, leading to false results. Red blood cell turnover in the bone marrow and the quality and heterogeneity of erythrocytes may influence the rate of hemoglobin glycation. By changing the structure of hemoglobin and inducing peroxidation, iron deficiency accelerates glycation. This review aims to discuss the possible causes of the association between increased levels of HbA1c and IDA.

HbA1c: a review of non-glycaemic variables

Identification of the correlation between HbA1c and diabetic complications has yielded one of the most clinically useful biomarkers. HbA1c has revolutionised the diagnosis and monitoring of diabetes mellitus. However, with widespread adoption of HbA1c has come increasing recognition that non-glycaemic variables can also affect HbA1c, with varying clinical significance. Furthermore, the identification of a discrepancy between predicted and measured HbA1c in some individuals, the so-called 'glycation gap', may be clinically significant. We aimed to review the current body of evidence relating to non-glycaemic variables to quantify any significance and provide subsequent suggestions. A PubMed-based literature search was performed, using a variety of search terms, to retrieve articles detailing the non-glycaemic variables suggested to affect HbA1c. Articles were reviewed to assess the relevance of any findings in clinical practice and where possible guidance is given. A range of non-glycaemic variables have statistically significant effects on HbA1c. While the clinical implications are generally irrelevant, a small number of non-glycaemic variables do have clinically significant effects and alternative biomarkers should be considered instead of, or in addition to, HbA1c. There are a small number of non-glycaemic variables which have a clinically significant effect on HbA1c, However, the vast majority of non-glycaemic variables have no clinical relevance. While clinicians should have an awareness of those non-glycaemic variables with clinical significance, in the vast majority of clinical scenarios HbA1c should continue to be used with confidence.

Alternate glycemic markers reflect glycemic variability in continuous glucose monitoring in youth with prediabetes and type 2 diabetes

OBJECTIVE

To determine whether the alternate glycemic markers, fructosamine (FA), glycated albumin (GA), and 1,5-anhydroglucitol (1,5AG), predict glycemic variability captured by continuous glucose monitoring (CGM) in obese youth with prediabetes and type 2 diabetes (T2D).

STUDY DESIGN

Youth with BMI ≥85th%ile, 10-18 years, had collection of fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), FA, GA, and 1,5AG and 72 hours of CGM. Participants with HbA1c ≥5.7% were included. Relationships between glycemic markers and CGM variables were determined with Spearman correlation coefficients. Linear models were used to examine the association between alternate markers and CGM measures of glycemic variability-standard deviation (SD) and mean amplitude of glycemic excursions (MAGE)-after controlling for HbA1c.

RESULTS

Total n = 56; Median (25th%ile, 75th%ile) age = 14.3 years (12.5, 15.9), 32% male, 64% Hispanic, 20% black, 13% white, HbA1c = 5.9% (5.8, 6.3), FA=211 mmol/L (200, 226), GA= 12% (11%, 12%), and 1,5AG = 22mcg/mL (19, 26). HbA1c correlated with average sensor glucose, AUC, SD, MAGE, and %time > 140 mg/dL. FA and GA correlated with average and peak sensor glucose, %time >140 and >200 mg/dL, and MAGE. GA also correlated with SD and AUC180. 1,5AG correlated with peak glucose, AUC180, SD, and MAGE. After adjusting for HbA1c, all 3 markers independently predicted MAGE; FA and GA independently predicted SD.

CONCLUSIONS

Alternate glycemic markers predict glycemic variability as measured by CGM in youth with prediabetes and T2D. After adjusting for HbA1c, these alternate markers continued to predict components of glycemic variability detected by CGM.

Family Consumer Behaviors, Adolescent Prediabetes and Diabetes in the National Health and Nutrition Examination Survey (2007-2010)

BACKGROUND

Prediabetes or diabetes (characterized by hemoglobin A1c [HbA1c] levels ≥ 5.7 gm%) has been associated with numerous long-term complications. Family consumer behaviors are important risk factors that lead to impaired glucose tolerance or diabetes. However, few studies have studied the association between the family consumer environment and prediabetes and diabetes in adolescents.

OBJECTIVE

The aim of this study was to examine the association between family consumer behaviors (healthy food availability and supermarket spending) and adolescent prediabetes and diabetes (ClinicalTrials.gov identifier #NCT03136289.) Methods: Data from a nationwide survey conducted by the Centers for Disease Control and Prevention (National Health and Nutrition Examination Survey [NHANES] 2007-2010 data) were used for these analyses. Adolescents aged 12-19 years were selected for this study. Bivariate analyses and logistic regression models assessed the relationship between family consumer behaviors and the prevalence of adolescent prediabetes and diabetes. Multivariable models adjusted for age, gender, ethnicity, physical activity, education, income, and household size.

RESULTS

A total of 2520 adolescents were eligible for this study. Adolescents with healthier household food availability had negative odds (odds ratio [OR] = 0.74, 95% confidence interval [CI], 0.55-1.00), as did higher log supermarket spending (OR = 0.69; 95% CI, 0.57-0.85). Interaction models demonstrated that adolescent females had more negative odds of prediabetes/diabetes for both healthier food availability (OR = 0.79, 95% CI, 0.39-1.29) and for greater log supermarket spending (OR = 0.69, 95% CI, 0.57-0.85).

CONCLUSION

This study shows that both healthy food availability and an increase in supermarket spending were associated with a decreased adjusted prevalence of prediabetes and diabetes in adolescents, with a greater effect in females. These results suggest the need for policy and dietary interventions targeting the consumer environment.

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.

Examining trends in prediabetes and its relationship with the metabolic syndrome in US adolescents, 1999-2014

AIMS

We sought to investigate temporal trends in prediabetes prevalence among US adolescents using two definitions and evaluate relationships with obesity and a MetS-severity score.

METHODS

We evaluated data from 5418 non-Hispanic white, non-Hispanic black, and Hispanic adolescents aged 12-19 participating in the National Health and Nutrition Examination Survey 1999-2014 with complete data regarding MetS and hemoglobin A1c (HbA1c). Prediabetes status was defined by American Diabetes Association (ADA) criteria: fasting glucose 100-125 mg/dL or HbA1c 5.7%-6.4%. MetS severity was assessed with a MetS-severity Z-score.

RESULTS

Prevalence of prediabetes as defined by HbA1c abnormalities significantly increased from 1999-2014, while prevalence of prediabetes as defined by fasting glucose abnormalities showed no significant temporal trend. There were variations in these trends across different racial/ethnic groups. MetS Z-score was overall more strongly correlated with HbA1c, fasting insulin, and the homeostasis model of insulin resistance than was BMI Z-score. These correlations were true in each racial/ethnic group with the exception that in non-Hispanic white adolescents, in whom the MetS Z-score was not significantly correlated with HbA1c measurements.

CONCLUSION

We found conflicting findings of temporal trends of US adolescent prediabetes prevalence based on the ADA's prediabetes criteria. The increasing prevalence of prediabetes by HbA1c assessment is concerning and raises the urgency for increased awareness and appropriate measures of prediabetes status among physicians and patients.

HbA1c and the Prediction of Type 2 Diabetes in Children and Adults

OBJECTIVE

Long-term data validating glycated hemoglobin (HbA1c) in assessing the risk of type 2 diabetes in children are limited. HbA1c, fasting plasma glucose (FPG), and 2-h postload plasma glucose (2hPG) concentrations were measured in a longitudinal study of American Indians to determine their utility in predicting incident diabetes, all of which is thought to be type 2 in this population.

RESEARCH DESIGN AND METHODS

Incident diabetes (FPG ≥126 mg/dL [7.0 mmol/L], 2hPG ≥200 mg/dL [11.1 mmol/L], HbA1c ≥6.5% [8 mmol/mol], or clinical diagnosis) was determined in 2,095 children without diabetes ages 10-19 years monitored through age 39, and in 2,005 adults ages 20-39 monitored through age 59. Areas under the receiver operating characteristic (ROC) curve for HbA1c, FPG, and 2hPG in predicting diabetes within 10 years were compared.

RESULTS

During long-term follow-up of children and adolescents who did not initially have diabetes, the incidence rate of subsequent diabetes was fourfold (in boys) as high and more than sevenfold (in girls) as high in those with HbA1c ≥5.7% as in those with HbA1c ≤5.3%-greater rate ratios than experienced by adults in the same HbA1c categories. Analyses of ROCs revealed no significant differences between HbA1c, FPG, and 2hPG in sensitivity and specificity for identifying children and adolescents who later developed diabetes.

CONCLUSIONS

HbA1c is a useful predictor of diabetes risk in children and can be used to identify prediabetes in children with other type 2 diabetes risk factors with the same predictive value as FPG and 2hPG.

Screening for type 2 diabetes and prediabetes in obese youth: evaluating alternate markers of glycemia - 1,5-anhydroglucitol, fructosamine, and glycated albumin

Hemoglobin A1c (HbA1c) is increasingly performed over the oral glucose tolerance test (OGTT) as the initial screening test for type 2 diabetes in youth. However, the optimal strategy for identifying type 2 diabetes in youth remains controversial. Alternate glycemic markers have been proposed as potentially useful tools for diabetes screening. We examined the relationships among fructosamine (FA), glycated albumin (GA), and 1,5-anhydroglucitol (1,5-AG) with traditional screening tests, HbA1c and OGTT. Youth 10-18 yrs, BMI ≥85th‰, and HbA1c <7.5% had a single visit with measurement of HbA1c, 1,5-AG, FA, GA, and a standard OGTT. Distributions of FA, GA, and 1,5-AG by HbA1c and 2-hour glucose (2hG) categories were compared. Receiver operating characteristic (ROC)-curves were generated to determine the cut points at which alternate markers maximized sensitivity and specificity for predicting prediabetes and diabetes. One hundred and seventeen, 62% female, 59% Hispanic, 22% White, 17% black, median 14.1 yr, and body mass index (BMI) z-score 2.3 participated. Median values of each alternate marker differed significantly between prediabetes and diabetes HbA1c and 2hG categories (p < 0.017). Only GA medians differed (p = 0.006) between normal and prediabetes HbA1c. Area under the receiver operating characteristic curves (ROC-AUCs) for alternate markers as predictors of prediabetes (0.5-0.66) were low; however, alternate marker ROC-AUCs for identifying diabetes (0.82-0.98) were excellent. Although the alternate markers were poor predictors of prediabetes, they all performed well predicting diabetes by 2hG and HbA1c. Whereas the usefulness of these markers for identifying prediabetes is limited, they may be useful in certain scenarios as second line screening tools for diabetes in overweight/obese youth.

Continuous glucose monitoring and its relationship to hemoglobin A1c and oral glucose tolerance testing in obese and prediabetic youth

CONTEXT

The optimal screening test for diabetes and prediabetes in obese youth is controversial.

OBJECTIVE

We examined whether glycosylated hemoglobin (HbA1c) or the oral glucose tolerance test (OGTT) is a better predictor of free-living glycemia as measured by continuous glucose monitoring (CGM).

DESIGN

This was a cross-sectional study of youth 10-18 years old, body mass index (BMI) 85th percentile or greater, with diabetes risk factors.

SETTING AND PARTICIPANTS

Participants (n = 118) with BMI 85th percentile or greater, not on medications for glucose management, were recruited from primary care and pediatric endocrinology clinics around Denver, Colorado.

INTERVENTION

HbA1c, fasting plasma glucose, and 2-hour glucose were collected and all participants wore a blinded CGM for 72 hours.

MAIN OUTCOME MEASURES

CGM outcomes were determined and descriptive statistics calculated. Performance characteristics at current American Diabetes Association cutpoints were compared with CGM outcomes.

RESULTS

CGM data were successfully collected on 98 obese youth. Those with prediabetes had significantly higher average glucose, area under the curve (AUC), peak glucose, and time greater than 120 and greater than 140 mg/dL (P < .01) on CGM than youth with normal HbA1c or OGTT. HbA1c had a greater magnitude of correlation to CGM average glucose, AUC, and minimum glucose; 2-hour glucose had a greater magnitude of correlation to CGM SD, peak glucose, and time greater than 140 and greater than 200 mg/dL. However, there were no overall differences in the strength comparisons between 2-hour glucose and HbA1c correlations to CGM outcomes.

CONCLUSIONS

In obese youth, HbA1c and 2-hour glucose performed equally well at predicting free-living glycemia on CGM, suggesting that both are valid tests for dysglycemia screening.

Advantages and pitfalls of fructosamine and glycated albumin in the diagnosis and treatment of diabetes

The efficient diagnosis and accurate monitoring of diabetic patients are cornerstones for reducing the risk of diabetic complications. The current diagnostic and prognostic strategies in diabetes are mainly based on two tests, plasma (or capillary) glucose and glycated hemoglobin (HbA1c). Nevertheless, these measures are not foolproof, and their clinical usefulness is biased by a number of clinical and analytical factors. The introduction of other indices of glucose homeostasis in clinical practice such as fructosamine and glycated albumin (GA) may be regarded as an attractive alternative, especially in patients in whom the measurement of HbA1c may be biased or even unreliable. These include patients with rapid changes of glucose homeostasis and larger glycemic excursions, and patients with red blood cell disorders and renal disease. According to available evidence, the overall diagnostic efficiency of GA seems superior to that of fructosamine throughout a broad range of clinical settings. The current method for measuring GA is also better standardized and less vulnerable to preanalytical variables than those used for assessing fructosamine. Additional advantages of GA over HbA1c are represented by lower reagent cost and being able to automate the GA analysis on many conventional laboratory instruments. Although further studies are needed to definitely establish that GA can complement or even replace conventional measures of glycemic control such as HbA1c, GA may help the clinical management of patients with diabetes in whom HbA1c values might be unreliable.

Are the ADA hemoglobin A(1c) criteria relevant for the diagnosis of type 2 diabetes in youth?

Diagnostic criteria for diabetes in children have not been established with nearly the rigor as that employed in adults. Recently revised American Diabetes Association (ADA) criteria allowed utilization of hemoglobin A(1c) (HbA1c) ≥ 6.5 % for diagnosis of diabetes. A recent series of pediatric studies appear to show that HbA1c has lower sensitivity than Fasting plasma glucose (FPG) or oral glucose tolerance test (OGTT). However, FPG and OGTT have themselves never been validated in children. Studies to validate diagnostic thresholds in children appear unlikely to take place. Thus, accepting the major ADA diagnostic criteria appears to be the best course of action for the pediatric community. One area in which correlation studies between HbA1c and FPG or OGTT might shed light is in the definition of criteria for intervention in 'pre-diabetes,' as the Diabetes Prevention Program Trial did not use HbA1c. However, such treatment, and the exact diagnostic thresholds at which it should be initiated in children, remains unproven.

Hemoglobin A1c measurement for the diagnosis of Type 2 diabetes in children

Laboratory measurements of hemoglobin A1c above 6.5% were approved as an additional diagnostic criteria for diabetes mellitus by the American Diabetes Association in 2010. Several recent pediatric studies have cast HbA1c measurement in children in an unfavorable light in the pediatric population, by comparing HbA1c measurements to results on oral glucose tolerance test (OGTT) or fasting plasma glucose (FPG). However, many of these studies do not recognize that diabetes diagnostic criteria are based upon long-term health outcomes. In this sense, OGTT and FPG have themselves never been validated in the pediatric population. Studies to validate diagnostic tests for diabetes in pediatric populations may take a substantial period of time, and may prove unfeasible. However, studies that tie diagnostic results as a child to diagnostic results as an adult may be more feasible and may provide the data needed to determine which pediatric diagnostic criteria to use. Thus, for the time being, except for cases of hemoglobinopathy, cystic fibrosis, and a few other exceptions, describing HbA1c as ‘lacking in sensitivity or specificity’ in the pediatric population because of lack of correlation with OGTT is not scientifically sound.