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

Racial differences in performance of HbA1c for the classification of diabetes and prediabetes among US adults of non-Hispanic black and white race

AIM

To characterize differences between black and white people in optimal HbA_1c thresholds for diagnoses of diabetes and prediabetes.

METHODS

Data were included from the National Health and Nutrition Examination Survey, 2005-2014. Black and white adults (age 18-70 years) who underwent an oral glucose tolerance test and had available fasting plasma glucose, 2-h plasma glucose and HbA_1c measurements were eligible for inclusion. Diabetes or prediabetes status was defined by fasting plasma glucose and 2-h plasma glucose using American Diabetes Association criteria. Classification of diabetes, prediabetes and dysglycaemia by HbA_1c was evaluated for a range of HbA_1c thresholds, with optimal thresholds defined as those values that maximized the sum of sensitivity and specificity (Youden's index).

RESULTS

In 5324 black (32.3%) and white (67.7%) individuals, Youden's index (optimal) thresholds for HbA_1c were ≥42 mmol/mol (6.0%) and ≥39 mmol/mol (5.7%) for discriminating diabetes vs non-diabetes, ≥ 44 mmol/mol (6.2%) and ≥39 mmol/mol (5.7%) for discriminating diabetes vs prediabetes (excluding normoglycaemia), ≥39 mmol/mol (5.7%) and ≥37 mmol/mol (5.5%) for discriminating dysglycaemia vs normoglycaemia, and ≥39 mmol/mol (5.7%) and ≥37 mmol/mol (5.5%) for discriminating prediabetes vs normoglycaemia (excluding diabetes), in black and white people, respectively.

CONCLUSIONS

Consistently higher optimal HbA_1c thresholds in black people than in white people suggest a need to individualize HbA_1c relative to glucose levels if HbA_1c is used to diagnose diabetes and prediabetes.

A labile form of hemoglobin A1c is higher in African-American youth with type 1 diabetes compared to Caucasian patients at similar glucose levels

BACKGROUND

Hemoglobin A1c (HbA1c) levels are higher in African-American (AA) individuals compared to Caucasians (EA) even after adjustment for blood glucose levels. To better understand the mechanism of this disparity we examined the relationship of an unstable (labile) form of HbA1c (L-HbA1c) with race and glucose.

METHODS

Samples for HbA1c were collected from pediatric patients self-identified as either AA (15F, 12M, age 13.4 ± 3.5 years) or EA (22F, 30M, age 14.6 ± 3.4 years) with type 1 diabetes at the time of a clinic visit. Clinic HbA1c (HbA1c) was performed by immunoassay. L-HbA1c equaled the difference in the HbA1c fraction by dynamic capillary isoelectric focusing before and after incubation in a low pH buffer. A capillary glucose (Clinic-BG) was measured at clinic visit. Mean blood glucose (MBG) was calculated from the last 30 days of the patient's glucose meter data. The influence of race on L-HbA1c was assessed in a multiple variable regression model adjusted for Clinic-BG.

RESULTS

The groups were similar for age and duration of diabetes. L-HbA1c was correlated with Clinic-BG, MBG, and HbA1c. The mean levels of L-HbA1c, HbA1c, MBG, but not Clinic-BG were higher in AA patients compared to EA. After adjustment for Clinic-BG, L-HbA1c was still higher in AA (2.8 ± 0.7% AA vs 2.1 ± 0.7% EA, P < .0001).

CONCLUSIONS

L-HbA1c is correlated with Clinic-BG. At any given level of Clinic-BG, AA patients have higher levels of L-HbA1c than EA. This preliminary study suggests that early factors prior to the formation of stable HbA1c may contribute to the observed glucose-independent racial disparity.

Self-Management as a Mediator of the Relationship between Social Support Dimensions and Health Outcomes of African American Adults with Type 2 Diabetes

Social support promotes behavior change and self-management that leads to improved health outcomes. The purpose of this study was to evaluate the role of self-management in mediating the relationship between social support dimensions and health outcomes of African Americans with type 2 diabetes (T2D). Cross-sectional data were collected from 102 African Americans with T2D at an outpatient clinic. The majority of the participants were female, single, unemployed, and having low income. Functional support, the quality of the primary intimate relationship, and the number of support persons were negatively correlated with depression. Functional support and satisfaction with support explained a significant small amount of the variance in self-management. However, self-management did not mediate the relationships between social support dimensions and the health outcomes. The results of this study shed the light on the unique relationships of social support dimensions with health outcomes of African Americans with T2D.

Total hemoglobin count has significant impact on A1C - Data from National Health and Nutrition Examination Survey 1999-2014

BACKGROUND

Previous study showed A1C was affected by hemoglobin and gender in non-anemic Koreans. However, there was no other data to support those important findings.

METHODS

Participants from National Health and Nutrition Examination Survey (NHANES) - 1999 to 2014 with age over 12 years were examined. After excluding participants with hypoglycemia and moderate to severe anemia, 22,974 participants were included in analysis. Both female and male were divided into three groups based on their hemoglobin level. Linear regression and multivariate regression analyses were conducted to assess the relationship between A1C and hemoglobin in three fasting plasma glucose (FPG) intervals.

RESULTS

For both female and male, A1C was significantly negatively correlated with hemoglobin in the FPG interval range between 80 to 126mg/dl, p<0.0001. A1C was not significantly associated with hemoglobin over the other two intervals (70≤FPG<80mg/dl and FPG≥126mg/dl, p>0.05). In addition, over FPG interval between 80 to 126mg/dl, after adjusting age and fasting glucose level, A1C still significantly negatively correlated with hemoglobin (regression coefficient=-0.052, p<0.0001 in females, regression coefficient=-0.050, p<0.0001 in males).

CONCLUSIONS

A1C would decrease by 0.05% (about 0.5mmol/mol) as a result of each 1g/dl increase in total hemoglobin count when plasma glucose level in normal or prediabetes range. The mechanism behind this finding is unclear. Further study should be conducted and hemoglobin count may need be taken into consideration when applying A1C for the diagnosis of diabetes or to screen for prediabetes.

Importance of early elevated maternal HbA1c levels in identifying adverse fetal and neonatal events

AIMS

The aims of this study were to explore factors that associated with gestational diabetes mellitus (GDM), and to determine the relationship between early maternal HbA1c levels and adverse fetal or neonatal events, and to determine an optimal maternal glucose testing method in order to decrease the potential health risk for their offspring.

METHODS

From December 2015 to May 2016, a total of 6744 pregnant women were enrolled from Shanghai First Maternal and Infant Hospital affiliated to Tongji University prospectively in the nested case-control study. Each GDM case was matched with a healthy pregnant woman and followed up. Outcome analyses were conducted between GDM case and control groups, as well as elevated and normal maternal HbA1c levels, respectively.

RESULTS

A total of 1836 women were included in the adverse fetal and neonatal events examination. For pregnant women with early HbA1c ≥ 5.2%, the adjusted risk ratios (RR) of respiratory distress syndrome (RDS), pneumonia and jaundice were 4.37 (95%CI 1.54-12.35), 2.03 (95%CI 1.24-3.33) and 1.49 (95%CI 1.01-2.20), respectively. After treatments, the frequency for the majority of events in GDM group was similar to that of healthy pregnant women. Moreover, the area under the curve (AUC) of early maternal HbA1c in predicting potential RDS is 0.734. HbA1c ≤ 4.9% excluded for RDS.

CONCLUSIONS

Compared with women with normal HbA1c, those with an early elevated HbA1c level were more likely to develop adverse events, including RDS, pneumonia and jaundice. Early HbA1c testing can be used as an auxiliary method identifying potential RDS.

Cardiovascular Health Among Non-Hispanic Asian Americans: NHANES, 2011-2016

Background Asian Americans are the fastest growing population in the United States, but little is known about their cardiovascular health (CVH). The objective of this study was to assess CVH among non-Hispanic Asian Americans (NHAAs) and to compare these estimates to those of non-Hispanic white (NHW) participants. Methods and Results Merging NHANES (National Health and Nutrition Examination Survey) data from 2011 to 2016, we examined 7 metrics (smoking, weight, physical activity, diet, blood cholesterol, blood glucose, and blood pressure) to assess CVH among 5278 NHW and 1486 NHAA participants aged ≥20 years. We assessed (1) the percentage meeting 6 to 7 metrics (ideal CVH), (2) the percentage meeting only 0 to 2 metrics (poor CVH), and (3) the overall mean CVH score. We compared these estimates between NHAAs and NHWs and among foreign-born NHAAs by birthplace and number of years living in the United States. The adjusted prevalence of ideal CVH was 8.7% among NHAAs and 5.9% among NHWs ( P<0.001). NHAAs were significantly more likely to have ideal CVH (adjusted prevalence ratio: 1.42; 95% CI, 1.29-1.55) compared with NHWs. Among NHAAs, there was no significant difference in ideal CVH between US- and foreign-born participants, nor by number of years living in the United States. With lower body mass index thresholds (<23, normal weight) for NHAAs, there were no statistically significant differences in the adjusted prevalence of ideal CVH (6.5% versus 5.9%, P=0.216) between NHAAs and NHWs. Conclusions NHAAs had a higher prevalence of overall ideal CVH compared with NHWs. However, when using a lower body mass index threshold for NHAAs, there was no difference in ideal CVH between the groups.

Global epidemiology of prediabetes - present and future perspectives

Prediabetes is defined as an intermediate state of hyperglycaemia with glucose levels above the normal state but below the diagnostic levels of diabetes. It is increasingly recognised as an important metabolic state, as individuals with prediabetes are at high risk of developing overt diabetes and its associated complications. A better understanding of prediabetes could help with earlier identification, thereby allowing earlier intervention, potentially lowering the number of individuals who go on to develop diabetes. The definitions and screening criteria for prediabetes differ between guidelines published by different organisations, resulting in estimations of prevalence that can vary widely from one another. Despite these differences, these estimates suggest that the number of individuals affected by prediabetes is increasing rapidly in all areas of the world. This short review compares and contrasts the diagnostic criteria for screening of prediabetes, the impact of various glycaemic measures on prevalence estimates, and discusses current and future trends in the global prevalence estimates of prediabetes.

Altered Glycemic Control Associated With Polymorphisms in the SLC22A1 (OCT1) Gene in a Mexican Population With Type 2 Diabetes Mellitus Treated With Metformin: A Cohort Study

The organic cation transporters OCT1 and OCT2 and the multidrug and toxin extrusion transporter MATE1, encoded by the SLC22A1, SLC22A2, and SLC47A1 genes, respectively, are responsible for the absorption of metformin in enterocytes, hepatocytes, and kidney cells. The aim of this study was to evaluate whether genetic variations in the SLC22A1, SLC22A2, and SLC47A1 genes could be associated with an altered response to metformin in patients with type 2 diabetes mellitus. A cohort study was conducted in 308 individuals with a diagnosis of type 2 diabetes mellitus of less than 3 years and who had metformin monotherapy. Three measurements of blood glycated hemoglobin (HbA_1c ) were obtained at the beginning of the study and after 6 and 12 months. Five polymorphisms were analyzed in the SLC22A1 (rs622342, rs628031, rs594709), SLC22A2 (rs316019), and SLC47A1 (rs2289669) genes by real-time polymerase chain reaction. The results showed a significant association among genotypes CC-rs622342 (β = 1.36; P < .001), AA-rs628031 (β = 0.98; P = .032), and GG-rs594709 (β = 1.21; P = .016) in the SLC22A1 gene with an increase in HbA_1c levels during the follow-up period. Additionally, a significant association was found in the CGA and CAG haplotypes with an increase in HbA_1c levels compared to the highest-frequency haplotype (AGA). In conclusion, the genetic variation in the SLC22A1 gene was significantly related to the variation of the HbA_1c levels, an important indicator of glycemic control in diabetic patients. This information may contribute to identifying patients with an altered response to metformin before starting their therapy.

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.

Clinical factors associated with persistently poor diabetes control in the Veterans Health Administration: A nationwide cohort study

OBJECTIVE

Patients with persistent poorly-controlled diabetes mellitus (PPDM) despite engagement in clinic-based care are at particularly high risk for diabetes complications and costs. Understanding this population's demographics, comorbidities and care utilization could guide strategies to address PPDM. We characterized factors associated with PPDM in a large sample of Veterans with type 2 diabetes.

METHODS

We identified a cohort of Veterans with medically treated type 2 diabetes, who received Veterans Health Administration primary care during fiscal years 2012 and 2013. PPDM was defined by hemoglobin A1c levels uniformly >8.5% during fiscal year (FY) 2012, despite engagement with care during this period. We used FY 2012 demographic, comorbidity and medication data to describe PPDM in relation to better-controlled diabetes patients and created multivariable models to examine associations between clinical factors and PPDM. We also constructed multivariable models to explore the association between PPDM and FY 2013 care utilization.

RESULTS

In our cohort of diabetes patients (n = 435,820), 12% met criteria for PPDM. Patients with PPDM were younger than better-controlled patients, less often married, and more often Black/African-American and Hispanic or Latino/Latina. Of included comorbidities, only retinopathy (OR 1.68, 95% confidence interval (CI): 1.63,1.73) and nephropathy (OR 1.26, 95% CI: 1.19,1.34) demonstrated clinically significant associations with PPDM. Complex insulin regimens such as premixed (OR 10.80, 95% CI: 10.11,11.54) and prandial-containing regimens (OR 18.74, 95% CI: 17.73,19.81) were strongly associated with PPDM. Patients with PPDM had higher care utilization, particularly endocrinology care (RR 3.56, 95% CI: 3.47,3.66); although only 26.4% of patients saw endocrinology overall.

CONCLUSION

PPDM is strongly associated with complex diabetes regimens, although heterogeneity in care utilization exists. While there is evidence of underutilization, inadequacy of available care may also contribute to PPDM. Our findings should inform tailored approaches to meet the needs of PPDM, who are among the highest-risk, highest-cost patients with diabetes.

When HbA1c and Blood Glucose Do Not Match: How Much Is Determined by Race, by Genetics, by Differences in Mean Red Blood Cell Age?

Commentary placing genetic ancestry markers and racial difference in HbA1c in the context of more common variations in the HbA1c-average glucose relationship and their clinical implications.

Glycated Hemoglobin and Outcomes of Heart Failure (from Get With the Guidelines-Heart Failure)

Glycated hemoglobin (HbA_1C) is a risk factor for new onset heart failure (HF). There is however a paucity of data evaluating its association with outcomes in patients with established HF. We assessed the relation of HbA_1C with outcomes among hospitalized HF patients. Among 41,776 HF patients from 263 hospitals participating to the Get with the Guidelines-HF registry between January 2009 and March 2016, we related HbA_1C to outcomes (in-hospital mortality, length of hospital stay, discharge to home, 30-day mortality, 30-day readmission, and 1-year mortality), using generalized estimating equation to account for within-hospital clustering and potential confounders. There were 68% of HF patients with diabetes and median HbA_1C was 7.1%. Each percent change in HbA_1C was associated with higher odds of discharge to home for HbA_1C levels <6.5% (covariate-adjusted odds ratio [OR] 1.13 [95% confidence interval 1.04 to 1.12]) or ≥6.5% (OR 1.05 [1.02 to 1.07]). After stratification by diabetes status, this association remained significant only among patients with diabetes (ORs for HbA_1C levels <6.5%: 1.17 [1.07 to 1.27]; and ≥6.5%: 1.06 [1.03 to 1.09]). Compared with the lowest HbA_1C tertile (HbA_1C ≤6.1%), patients in the highest HbA_1C tertile (HbA_1C 7.3% to 19%) were more likely to have a length of hospital stay >4 days (OR 1.10 [1.02 to 1.18]) and to be discharged home (OR 1.23 [1.14 to 1.33]). There were no significant association between HbA_1C and the following outcomes: in-hospital mortality, 30-day mortality, 30-day readmission, and 1-year mortality. In conclusion, among hospitalized HF patients, HbA_1C was associated with prolonged hospital stay and home discharge, but not with readmission, short-term, or intermediate-term mortality.

Associations of dietary intake with cardiometabolic risk in a multi-ethnic cohort: a longitudinal analysis of the Determinants of Adolescence, now young Adults, Social well-being and Health (DASH) study

Unfavourable dietary habits, such as skipping breakfast, are common among ethnic minority children and may contribute to inequalities in cardiometabolic disease. We conducted a longitudinal follow-up of a subsample of the UK multi-ethnic Determinants of Adolescent Social well-being and Health cohort, which represents the main UK ethnic groups and is now aged 21–23 years. We aimed to describe longitudinal patterns of dietary intake and investigate their impact on cardiometabolic risk in young adulthood. Participants completed a dietary behaviour questionnaire and a 24 h dietary intake recall; anthropometry, blood pressure, total cholesterol and HDL-cholesterol and HbA1c were measured. The cohort consisted of 107 White British, 102 Black Caribbean, 132 Black African, 98 Indian, 111 Bangladeshi/Pakistani and 115 other/mixed ethnicity. Unhealthful dietary behaviours such as skipping breakfast and low intake of fruits and vegetables were common (56, 57 and 63 %, respectively). Rates of skipping breakfast and low fruit and vegetable consumption were highest among Black African and Black Caribbean participants. BMI and cholesterol levels at 21–23 years were higher among those who regularly skipped breakfast at 11–13 years (BMI 1·41 (95 % CI 0·57, 2·26), P=0·001; cholesterol 0·15 (95 % CI –0·01, 0·31), P=0·063) and at 21–23 years (BMI 1·05 (95 % CI 0·22, 1·89), P=0·014; cholesterol 0·22 (95 % CI 0·06, 0·37), P=0·007). Childhood breakfast skipping is more common in certain ethnic groups and is associated with cardiometabolic risk factors in young adulthood. Our findings highlight the importance of targeting interventions to improve dietary behaviours such as breakfast consumption at specific population groups.

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.

Prevalence of metabolic syndrome and the comparison of fasting plasma glucose and HbA1c as the glycemic criterion for MetS definition in non-diabetic population in Ghana

BACKGROUND

Glycated hemoglobin (HbA1c), owing to its ability to reflect glycemia over a relatively longer time span, is still been investigated as an adjunct test for fasting plasma glucose (FPG) to identify subjects at risk of metabolic syndrome (MetS) in some Caucasian populations. However, whether or not HbA1c can serve as an adjunct to FPG in the definition of MetS in the Ghanaian population remains unknown. This study determined the prevalence of MetS and evaluated HbA1c ≥ 5.6% and FPG ≥ 5.6 mmol/l as the glycemic component of MetS among non-diabetic population in Ghana.

METHODS

This was a case-control study conducted at St Francis Xavier Hospital, Assin Fosu, Central Region, Ghana. A total of 264 non-diabetic Ghanaian adults consisting of 158 newly diagnosed hypertensives and 106 normotensives, were recruited for the study. Fasting plasma insulin and glucose, HbA1c, and lipid profile was performed for each respondent.

RESULTS

Using the FPG as glycemic criterion, the overall MetS prevalence was 46.6%, 37.1%, and 12.5% according by the IDF, NCEP ATP III, and WHO criteria, respectively. The prevalence of MetS using the HbA1c criterion was 54.2%, 52.7%, and 42.4% by the IDF, NCEP ATP III and WHO criteria, respectively. The HbA1c criterion identified more participants with MetS compared to the FPG criterion with a good agreement between HbA1c and FPG using the IDF and NCEP ATP III criteria (κ = 0.484 to 0.899) respectively. However, the overlap between HbA1c and FPG based diagnosis of MetS was limited for the WHO criterion.

CONCLUSION

The prevalence of metabolic syndrome is high among non-diabetics in Ghana. Introduction of HbA1c in addition to FPG in the screening of MetS improves identification of more people with MetS who would otherwise have been missed when only FPG-based diagnosis of MetS is used; with a substantial agreement with FPG, except when using the WHO criteria.

A Comparison of Biomarkers in the Assessment of Glycemic Control in Diabetes: Reviewing the Evidence

BACKGROUND

Diabetes Mellitus (DM) is a chronic life-long progressive multisystem heterogeneous metabolic disorder with complex pathogenesis.

INTRODUCTION

Hyperglycemia is not only one of the classical signs of DM, but it also serves as the pivotal prerequisite for the diagnosis of the disease. However, with the advancement in the field of analytical biochemistry, a number of alternative and specific biomarkers have been discovered which can be used for better diagnosis of the DM. In this review, we have discussed various aspects of DM and different biomarkers used in assessing glycemia.

METHODOLOGY

A thorough literature survey was conducted to identify various studies that reported the use of conventional and non-conventional markers for the assessment of glycemia in DM patients.

CONCLUSION

The accurate detection and hence diagnosis of DM has become easy and more specific with the use of various biomarkers.

2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes-2019

The American Diabetes Association (ADA) "Standards of Medical Care in Diabetes" includes 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, a multidisciplinary 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, please refer to the Standards of Care Introduction Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Correlation of maternal A1c with glucose infusion rate requirements in the newborn

OBJECTIVE

Fetal hyperinsulinemia and neonatal hyperglycemia are complications of poor maternal glycemic control and may result in increased glucose infusion rate (GIR) requirements in infants of diabetic mothers (IDMs). The objectives of this study were to correlate maternal A1c levels with GIR requirements in IDMs, establish an A1c threshold predictive for GIR requirements, and identify associations between A1c levels and complications in IDMs.

STUDY DESIGN

A retrospective review of paired maternal A1c values and GIR requirements of IDMs were compared via logistic regression analysis. A likelihood ratio was calculated to correlate A1c levels with GIR requirements, and identify a maternal A1c threshold.

RESULTS

Increasing A1c values were significantly correlated with GIR≥5 mg/kg/min (OR, 1.37; 95% CI 1.04-1.79, p = 0.021). Macrosomia was the most frequent complication (OR, 1.31; 95% CI 1.04-1.67, p = 0.022) and A1c > 6.8% was predictive for increased GIR requirements.

CONCLUSION

Increased A1c values were significantly associated with GIR requirements≥5 mg/kg/min. Increased maternal A1c is significantly associated with complications in newborns, specifically macrosomia. A maternal A1c of 6.8% was identified as a threshold predictive of increased GIR requirements.

Association between hemoglobin glycation index and cardiometabolic risk factors in Korean pediatric nondiabetic population

PURPOSE

The hemoglobin glycation index (HGI) represents the degree of nonenzymatic glycation and has been positively associated with cardiometabolic risk factors (CMRFs) and cardiovascular disease in adults. This study aimed to investigate the association between HGI, components of metabolic syndrome (MS), and alanine aminotransferase (ALT) in a pediatric nondiabetic population.

METHODS

Data from 3,885 subjects aged 10-18 years from the Korea National Health and Nutrition Examination Survey (2011-2016) were included. HGI was defined as subtraction of predicted glycated hemoglobin (HbA1c) from measured HbA1c. Participants were divided into 3 groups according to HGI tertile. Components of MS (abdominal obesity, fasting glucose, triglycerides, high-density lipoprotein cholesterol, and blood pressure), and proportion of MS, CMRF clustering (≥2 of MS components), and elevated ALT were compared among the groups.

RESULTS

Body mass index (BMI) z-score, obesity, total cholesterol, ALT, abdominal obesity, elevated triglycerides, and CMRF clustering showed increasing HGI trends from lower-to-higher tertiles. Multiple logistic regression analysis showed the upper HGI tertile was associated with elevated triglycerides (odds ratio, 1.65; 95% confidence interval, 1.18-2.30). Multiple linear regression analysis showed HGI level was significantly associated with BMI z-score, HbA1c, triglycerides, and ALT. When stratified by sex, age group, and BMI category, overweight/obese subjects showed linear HGI trends for presence of CMRF clustering and ALT elevation.

CONCLUSION

HGI was associated with CMRFs in a Korean pediatric population. High HGI might be an independent risk factor for CMRF clustering and ALT elevation in overweight/obese youth. Further studies are required to establish the clinical relevance of HGI for cardiometabolic health in youth.

Hemoglobin glycation index predicts cardiovascular disease in people with type 2 diabetes mellitus: A 10-year longitudinal cohort study

BACKGROUND AND AIMS

Previous studies have suggested that the hemoglobin glycation index (HGI) can be used as a predictor of diabetes-related complications. We examined the prognostic significance of a high HGI for cardiovascular disease (CVD) in an ongoing hospital-based cohort.

METHODS

From March 2003 to December 2004, 1302 consecutive patients with type 2 diabetes and without a prior history of CVD were enrolled. CVD was defined as the occurrence of coronary artery disease or ischemic stroke. The HGI was calculated as the measured glycated hemoglobin (HbA1c) minus predicted HbA1c. Predicted HbA1c were calculated for 1302 participants by inserting fasting blood glucose (FBG) into the equation, Predicted HbA1c level = 0.02106 × FBG [mg/dL] + 4.973. Cox proportional hazards models were used to identify the associations between the HGI and CVD after adjusting for confounding variables.

RESULTS

During 11.1 years of follow-up, 225 participants (17.2%) were newly diagnosed with CVD. The baseline HGI was significantly higher in subjects with incident CVD than in those without CVD, although the baseline FBG levels did not differ according to the occurrence of CVD. Compared with patients without CVD, those with CVD were older, had a longer duration of diabetes and hypertension, and used more insulin at baseline. A Cox hazard regression analysis revealed that the development of CVD was significantly associated with baseline HGI (hazard ratio [HR], 1.94; 95% confidence interval [CI], 1.31-2.87; p < 0.001, comparing the highest and lowest quartiles of HGI). This relationship was unchanged after additional adjustment for baseline HbA1c level (HR, 1.74; 95% CI, 1.08-2.81). The HRs of HbA1c in relation to outcomes were similar to or lower than those seen for HGI. After adjustment for HGI, the effect of the highest HbA1c on incident CVD disappeared.

CONCLUSIONS

High HGI was independently associated with incident CVD in patients with type 2 diabetes. Patients with high HGI at baseline had a higher inherent risk for CVD.

Issues in Defining the Burden of Prediabetes Globally

PURPOSE OF REVIEW

Using a global perspective, this review collates evidence on the heterogeneity of prediabetes definitions and diagnostic methods, their clinical and public health implications, and discusses possible options for improvement.

RECENT FINDINGS

Our review notes that the concept of prediabetes is increasingly recognized worldwide, but against a background of non-uniform definition and diagnostic criteria. This results in widely varying burden estimation. Current evidence shows a variety of prediabetes phenotypes. This reflects biological and diagnostic heterogeneity, resulting from the use of different tests (glucose or HbA_1C) and thresholds to define prediabetes. The biological and diagnostic variabilities have implications for the characterization of the burden of prediabetes, natural history, prognosis, screening, implementation of lifestyle or drug interventions to mitigate related health risks, and monitoring of the effects of such interventions.

Biological and socioeconomic determinants of prediabetes in youth: an analysis using 2007 to 2011 Canadian Health Measures Surveys

OBJECTIVES

To describe rates of prediabetes among youth in Canada and the associated social and biological characteristics.

METHODS

We analyzed the cross-sectional data from the first (2007-2009) and second (2009-2011) cycles of the Canadian Health Measures Survey (CHMS) for youth aged 6-19 years. Prediabetes was defined using the glycated hemoglobin (A1C) guidelines set out by the American Diabetes Association (ADA) and the Canadian Diabetes Association (CDA) of A1C ranges 5.7-6.4% (38.8-46.4 mmol/mol) and 6.0-6.4% (42.1-46.4 mmol/mol), respectively.

RESULTS

An elevated A1C was observed in 22.8% of our sample (n = 3449) based on the ADA definition and 5.2% of youth using the CDA definition. Independent predictors in a fully adjusted model for prediabetes were non-White (odds ratio (OR) 2.62: 95% Confidence intervals 2.05-3.35), obese (OR 1.53: 1.19-1.96), less physically active youth (0.97: 0.95-0.99), and parents with high school education or less (1.34: 1.02-1.74). Moreover, significant regional variations were noted with higher rates for all regions except Ontario.

CONCLUSION

Prediabetes is relatively common in Canada and associated with common biologic and socioeconomic factors. Importantly, regular physical activity was significantly associated with reduced odds of prediabetes. Targeted screening and continued emphasis on physical activity may help curb the increasing rates of prediabetes.

Impact of Patient-Centered Medical Home Implementation on Diabetes Control in the Veterans Health Administration

BACKGROUND

Given its widespread dissemination across primary care, the Veterans Health Administration (VA) is an ideal setting to examine the impact of the patient-centered medical home (PCMH) on diabetes outcomes.

OBJECTIVE

To assess the impact of PCMH implementation on diabetes outcomes among patients receiving care in the Veterans Health Administration.

DESIGN

Retrospective cohort analysis and multilevel logistic regression.

PATIENTS

Twenty thousand eight hundred fifty-eight patients in one Midwest VA network who had a diabetes diagnosis in both 2009 and 2012 and who received primary care between October 1, 2008 and September 30, 2009.

MAIN MEASURES

Glycemic and lipid control using VA quality indicators [hemoglobin (Hb) A1c < 9%, low-density lipoprotein cholesterol (LDL-C) < 100 mg/dL].

KEY RESULTS

Odds of glycemic control were lower in 2012 than 2009 (OR = 0.72, 95% CI = 0.67-0.77, p  < 0.001), and this change in control over time varied by race (OR of the interaction between time and race = 1.18, 95% CI = 1.02-1.36, p  = 0.028). While the disparity in glycemic control between white and black patients persisted post-PCMH, the magnitude of the disparity was smaller in 2012 compared to 2009 (2012: OR = 1.32, 95% CI = 1.18-1.47, p  < 0.0001 and 2009: OR = 1.59, 95% CI = 1.39-1.82, p  < 0.0001). Odds of lipid control did not significantly change between 2009 and 2012 and change did not vary by race and/or gender.

CONCLUSIONS

Although there were no significant improvements in odds of lipid control, and odds of glycemic control decreased following PCMH implementation, there was evidence of reduced racial disparities in glycemic control post-PCMH implementation.

Contributions of A1c, fasting plasma glucose, and 2-hour plasma glucose to prediabetes prevalence: NHANES 2011-2014

PURPOSE

Our goal was to characterize the contributions of A1c, fasting plasma glucose, and 2-hour plasma glucose to prediabetes prevalence and to characterize how those contributions differ among U.S. population subgroups.

METHODS

In the 2011-2014 National Health and Nutrition Examination Survey, a nationally representative sample of the U.S. population, among participants without diabetes (N = 3387), we created area-proportional three-Venn diagrams showing the proportion above the prediabetes cutpoint for each of the three markers in the overall population and in subgroups defined by age, race/ethnicity, sex, and body mass index.

RESULTS

In the overall population, 28.3% had fasting plasma glucose above the prediabetes cutpoint, 21.7% had A1c above the prediabetes cutpoint, and 13.3% had 2-hour plasma glucose above the prediabetes cutpoint. Adolescents and young adults tended to have only one marker exceed the prediabetes cutpoint, while older age groups tended to have multiple markers above the prediabetes cutpoint. For non-Hispanic whites, non-Hispanic blacks, non-Hispanic Asians, and Mexican-Americans, the unadjusted total percent above the A1c cutpoint was 19.3%, 36.4%, 20.5%, and 21.4%, respectively.

CONCLUSIONS

We provide a graphic reference showing fasting plasma glucose was the largest contributor to prediabetes prevalence in the overall population, followed by A1c and then 2-hour plasma glucose.

Identifying Prediabetes and Type 2 Diabetes in Asymptomatic Youth: Should HbA1c Be Used as a Diagnostic Approach?

PURPOSE OF REVIEW

Because the incidence of type 2 diabetes and prediabetes in children is rising, routine screening of those at risk is recommended. In 2010, the ADA made the recommendation to include hemoglobin A1c (HbA1c) as a diagnostic test for diabetes, in addition to the oral glucose tolerance test or fasting plasma glucose. Our objective was to assess the pediatric literature with regard to HbA1c test performance and discuss advantages and disadvantages of use of the test for diagnostic purposes.

RECENT FINDINGS

HbA1c has a number of advantages, including elimination of the need for fasting, lower variability, assay standardization, and long-term association with future development of diabetes. It also has many drawbacks. It can be affected by a number of non-glycemic factors, including red blood cell turnover, hemoglobinopathies, medications, race, and age. In particular, it performs differently in children compared with adults, generally with lower sensitivity for prediabetes (as low as 0-5% in children vs 23-27% in adults) and lower area under the receiver operating characteristic curve (AUC) (0.53 vs 0.73 for prediabetes), and it has lower efficacy at a higher cost, compared with other tests of glycemia. Finally, HbA1c may perform very differently across diverse populations according to race/ethnicity; in Chinese populations, the proportion of individuals classified with prediabetes based on HbA1c predominates compared with IFG (77% for HbA1c vs 27.7% for IFG), whereas in US populations, it is the opposite (24.8% for HbA1c vs 80.1% for FPG). HbA1c is controversial because although it is convenient, it is not a true measure of glycemia. The interpretation of HbA1c results requires a nuanced understanding that many primary care physicians who are ordering the test in greater numbers do not possess. Alternative markers of glycemia may hold promise for the future but are not yet endorsed for use in practice. Further studies are needed to determine appropriate thresholds for screening tests and the long-term impact of screening and identification.

The Starr County Border Health Initiative: Focus Groups on Diabetes Prevention in Mexican Americans

Purpose The purpose of the study was to conduct focus groups with Mexican Americans in an impoverished rural community on the Texas-Mexico border to identify current barriers to adopting healthier lifestyles and to obtain recommendations for diabetes prevention. Methods Three separate 2-hour focus groups were led by an experienced bilingual Mexican American moderator. Interviews included questions about cultural factors and barriers that influence lifestyle behaviors, aspects of previous diabetes self-management interventions that were helpful for motivating behavioral change, and recommendations for diabetes prevention. Results Twenty-seven participants attended a focus group session; each session involved 7 to 12 informants. Individuals were diagnosed with prediabetes or type 2 diabetes mellitus; most were female, foreign born, and Spanish speaking. Interviews documented the cultural importance of food. Informants raised priority issues for diabetes prevention, including the need to learn how to prepare healthier foods and track caloric intake. Major barriers to healthier lifestyles included high costs of healthy foods, fatigue from busy schedules and working multiple jobs, a cultural view that exercise is a waste of valuable time, and fear of deportation. Conclusions Cultural influences and barriers to implementing healthy lifestyles should be assessed regularly and strategies implemented to overcome them. Such factors may change as environmental, sociocultural, and political environments change.

Translating the HbA1c assay into estimated average glucose values in children and adolescents with type 1 diabetes mellitus

OBJECTIVE

The A1c assay, expressed as the percent of hemoglobin that is glycated, measures chronic glycemia and is widely used to judge the adequacy of diabetes treatment and adjust therapy. Day-to-day management is guided by self-monitoring of capillary glucose concentrations (milligrams per decilitre or millimoles per litter) as well as by using continuous glucose monitoring systems (CGMS). We found a mathematical relationship between A1c and average glucose (AG) levels measured by CGMS over 5 days and determined the correlation between the variable CGMS parameters and HbA1c in 50 children with type 1 diabetes mellitus (DM-1) on MDI therapy.

RESEARCH DESIGN AND METHODS

A total of 50 diabetic children randomly selected from a cohort of children with DM-1 were included in the analyses. A1c levels obtained at the end of 3 months and measured in a central laboratory were compared with the AG levels during the previous 5 days recorded by CGMS. AG was calculated by combining weighted results from 5 days of continuous glucose monitoring performed before measuring HbA1c, with 3-5 point daily self-monitoring of capillary (fingerstick) glucose.

RESULTS

Linear regression analysis between the A1c and AG values provided the tightest correlations HbA1c=0.0494 MG- 2E-14, R2=0.90, P<0.0001), allowing calculation of an estimated average glucose (eAG) for A1c values.

CONCLUSIONS

Our study showed a linear relationship between HbA1C and AG values measured by CGMS for 5 days before HbA1c measurement. The AG can be easily calculated using a formula derived from linear regression analysis of HbA1c data obtained in our diabetic children.

Hemoglobin A1c and diagnosis of diabetes

The prevalence of diabetes is increasing markedly worldwide, especially in China. Hemoglobin A1c is an indicator of mean blood glucose concentrations and plays an important role in the assessment of glucose control and cardiovascular risk. In 2010, the American Diabetes Association included HbA1c ≥6.5% into the revised criteria for the diagnosis of diabetes. However, the debate as to whether HbA1c should be used to diagnose diabetes is far from being settled and there are still unanswered questions regarding the cut-off value of HbA1c for diabetes diagnosis in different populations and ethnicities. This review briefly introduces the history of HbA1c from discovery to diabetes diagnosis, key steps towards using HbA1c to diagnose diabetes, such as standardization of HbA1c measurements and controversies regarding HbA1c cut-off points, and the performance of HbA1c compared with glucose measurements in the diagnosis of diabetes.

Glycated albumin in chronic kidney disease: Pathophysiologic connections

Nephropathy in diabetes patients is the most common etiology of end-stage kidney disease (ESKD). Strict glycemic control reduces the development and progression of diabetes-related complications, and there is evidence that improved metabolic control improves outcomes in subjects having diabetes mellitus with advanced chronic kidney disease (CKD). Glycemic control in people with kidney disease is complex. Changes in glucose and insulin homoeostasis may occur as a consequence of loss of kidney function and dialysis. The reliability of measures of long-term glycemic control is affected by CKD and the accuracy of glycated haemoglobin (HbA1c) in the setting of CKD and ESKD is questioned. Despite the altered character of diabetes in CKD, current guidelines for diabetes management are not specifically adjusted for this patient group. The validity of indicators of long-term glycemic control has been the focus of increased recent research. This review discusses the current understanding of commonly used indicators of metabolic control (HbA1c, fructosamine, glycated albumin) in the setting of advanced CKD.

Haemoglobin glycation index and risk for diabetes-related complications in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial

AIMS/HYPOTHESIS

Previous studies have suggested that the haemoglobin glycation index (HGI) can be used as a predictor of diabetes-related complications in individuals with type 1 and type 2 diabetes. We investigated whether HGI was a predictor of adverse outcomes of intensive glucose lowering and of diabetes-related complications in general, using data from the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial.

METHODS

We studied participants in the ADVANCE trial with data available for baseline HbA_1c and fasting plasma glucose (FPG) (n = 11,083). HGI is the difference between observed HbA_1c and HbA_1c predicted from a simple linear regression of HbA_1c on FPG. Using Cox regression, we investigated the association between HGI, both categorised and continuous, and adverse outcomes, considering treatment allocation (intensive or standard glucose control) and compared prediction of HGI and HbA_1c.

RESULTS

Intensive glucose control lowered mortality risk in individuals with high HGI only (HR 0.74 [95% CI 0.61, 0.91]; p = 0.003), while there was no difference in the effect of intensive treatment on mortality in those with high HbA_1c. Irrespective of treatment allocation, every SD increase in HGI was associated with a significant risk increase of 14-17% for macrovascular and microvascular disease and mortality. However, when adjusted for identical covariates, HbA_1c was a stronger predictor of these outcomes than HGI.

CONCLUSIONS/INTERPRETATION

HGI predicts risk for complications in ADVANCE participants, irrespective of treatment allocation, but no better than HbA_1c. Individuals with high HGI have a lower risk for mortality when on intensive treatment. Given the discordant results and uncertain relevance beyond HbA_1c, clinical use of HGI in type 2 diabetes cannot currently be recommended.

Glycaemic indices and haemoglobin A1c as predictors for non-healing ulcers

OBJECTIVE

Non-healing lower extremity ulcers (NHLU) are a common podiatric complication of diabetes, with poor glycaemic control as a risk factor for development. Glycaemic indices, such as haemoglobin A1c (HbA1c) and fasting plasma glucose (FPG), are used to diagnose and to monitor diabetes. Using a population-based, nationally representative sample, we evaluate the relationship between glycaemic indices and NHLU (as defined by the patient) to propose glycaemic thresholds for clinical suspicion of patient NHLU status.

METHOD

Using data from the 1999-2004 National Health and Nutrition Examination Surveys (NHANES), a total of 9769 adults (≥40 years old) with available self-reported diabetes and NHLU status were analysed. Glycaemic index markers, including FPG and HbA1c, were assessed via laboratory analysis from serum blood samples. Logistic regression models were fitted to determine optimal thresholds for FPG and HbA1c to predict NHLU status.

RESULTS

Compared with those without NHLU, NHLU patients were older, male, had higher rates of diabetes, were more likely to take insulin, and had lower total cholesterol. Youden's Index for NHLU identified the optimal FPG threshold as 117.7mg/dl (sensitivity: 33.5%; specificity: 82.6%). The optimal HbA1c threshold was 5.9% (sensitivity: 43.2%; specificity: 77.3%). HbA1c (Odds ratio (OR) 2.44, 95% Confidence Interval (CI) 1.96-3.05; Area under curve (AUC) 0.62) was a stronger discriminator of NHLU compared to FPG (OR 2.19; 95%CI 1.57-3.05; AUC 0.60).

CONCLUSION

This study identified glycaemic thresholds for suspicion of NHLU development that are lower than the glucose goal levels recommended as optimal by the American Diabetes Association. Health professionals should be aware of these glycaemic indices when screening patients with diabetes for NHLU. Future longitudinal and validation studies are necessary to better discern the ideal glycaemic index thresholds to identify NHLU.

Association between White Blood Cell Counts within Normal Range and Hemoglobin A1c in a Korean Population

BACKGROUND

We examined whether white blood cell (WBC) count levels within normal range, could be associated with hemoglobin A1c (HbA1c) levels.

METHODS

Among the 11,472 people (≥19 years of age) who participated in the 2011 to 2012 Korea National Health and Nutrition Examination, subjects with chronic disease or illness, including 807 patients with diabetes currently taking anti-diabetic medications and/or 1,149 subjects with WBC levels <4,000 or >10,000/μL were excluded.

RESULTS

Overall, adjusted HbA1c levels increased across the WBC quartiles (5.55%±0.01%, 5.58%±0.01%, 5.60%±0.01%, and 5.65%±0.01%, P<0.001) after adjusting for confounding factors, such as age, gender, fasting plasma glucose, college graduation, smoking history, waist circumference, presence of hypertension, serum total cholesterol, serum triglyceride, and presence of anemia. The adjusted proportions (%) of HbA1c levels of ≥5.7%, ≥6.1%, and ≥6.5% showed significant increases across WBC quartiles (P<0.001, P=0.002, and P=0.022, respectively). Logistic regression analyses of WBC quartiles for the risk of HbA1c levels of ≥5.7%, ≥6.1%, and ≥6.5%, using the variables above as covariates, showed that the odds ratios of the fourth quartile of WBCs were 1.59 (95% confidence interval [CI], 1.35 to 1.89; P<0.001), 1.78 (95% CI, 1.31 to 2.42; P<0.001), and 2.03 (95% CI, 1.13 to 3.64; P=0.018), using the first quartile of WBCs as the reference.

CONCLUSION

HbA1c levels were positively associated with WBC levels within normal range in a general adult population.

Diabetic Kidney Disease: Is There a Role for Glycemic Variability?

PURPOSE OF REVIEW

Diabetes is the leading cause of kidney disease globally. Diabetic kidney disease (DKD) is a heterogeneous disorder manifested as albuminuria and/or decreasing GFR. Hyperglycemic burden is the major contributor to the development of DKD. In this article, we review the evidence for the contribution of glycemic variability and the pitfalls associated with use of hemoglobin A1c (A1C), the gold standard for assessment of glucose control, in the setting of DKD.

RECENT FINDINGS

Glycemic variability, characterized by swings in blood glucose levels, can result in generation of mitochondrial reactive oxygen species, a putative inciting factor for hyperglycemia-induced alterations in intracellular metabolic pathways. While there is indirect evidence supporting the role of glycemic variability in the pathogenesis of DKD, definitive data are lacking. A1C has many limitations and is a particularly suboptimal measure in patients with kidney disease, because its accuracy is compromised by variables affecting RBC survival and other factors. Continuous glucose monitoring (CGM) technology has the potential to enable us to use glucose as a more important clinical tool, for a more definitive understanding of glucose variability and its role in DKD. Glycemic variability may be a factor in the development of DKD, but definitive evidence is lacking. Currently, all available glycemic biomarkers, including A1C, have limitations and in the setting of DKD and should be used cautiously. Emerging data suggest that personal and professional CGM will play an important role in managing diabetes in patients with DKD, where risk of hypoglycemia is high.

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.

Translating the HbA1c assay into estimated average glucose values in children and adolescents with type 1 diabetes mellitus

OBJECTIVE

The A1c assay, expressed as the percent of hemoglobin that is glycated, measures chronic glycemia and is widely used to judge the adequacy of diabetes treatment and adjust therapy. Day-to-day management is guided by self-monitoring of capillary glucose concentrations (milligrams per decilitre or millimoles per litter) as well as by using continuous glucose monitoring systems (CGMS). We found a mathematical relationship between A1c and average glucose (AG) levels measured by CGMS over 5 days and determined the correlation between the variable CGMS parameters and HbA1c in 50 children with type 1 diabetes mellitus (DM-1) on MDI therapy.

RESEARCH DESIGN AND METHODS

A total of 50 diabetic children randomly selected from a cohort of children with DM-1 were included in the analyses. A1c levels obtained at the end of 3 months and measured in a central laboratory were compared with the AG levels during the previous 5 days recorded by CGMS. AG was calculated by combining weighted results from 5 days of continuous glucose monitoring performed before measuring HbA1c, with 3-5 point daily self-monitoring of capillary (fingerstick) glucose.

RESULTS

Linear regression analysis between the A1c and AG values provided the tightest correlations HbA1c=0.0494 MG- 2E-14, R2=0.90, P<0.0001), allowing calculation of an estimated average glucose (eAG) for A1c values.

CONCLUSIONS

Our study showed a linear relationship between HbA1C and AG values measured by CGMS for 5 days before HbA1c measurement. The AG can be easily calculated using a formula derived from linear regression analysis of HbA1c data obtained in our diabetic children.

2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes-2018

The American Diabetes Association (ADA) "Standards of Medical Care in Diabetes" includes 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, a multidisciplinary 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, please refer to the Standards of Care Introduction Readers who wish to comment on the Standards of Care are invited to do so at professional.diabetes.org/SOC.

Association between hemoglobin glycation index and hepatic steatosis in non-diabetic individuals

AIMS

Hemoglobin glycation index (HGI), which is the difference between the observed value of HbA1 and the predicted HbA1c based on plasma glucose levels, represents a measure of the degree of non-enzymatic glycation of hemoglobin and it has been found to be positively associated with diabetic complications. Herein we investigated whether HGI is associated with hepatic steatosis and related biomarkers in subjects without diabetes.

METHODS

1120 White individuals without diabetes were stratified in quartiles according to HGI levels. Hepatic steatosis was diagnosed by ultrasonography.

RESULTS

As compared with subjects in the lowest quartile of HGI those in the intermediate and high HGI groups displayed an unfavorable cardio-metabolic risk profile having significantly higher values of body mass index (BMI), waist circumference, % fat mass, total cholesterol, triglycerides, inflammatory markers such as high sensitivity C reactive protein, erythrocytes sedimentation rate, complement C3, platelets and white blood cell count, hepatic insulin resistance assessed by the liver IR index and lower concentrations of high-density lipoprotein. HGI was positively associated with the biomarker of liver damage alanine aminotransferase, and fatty liver index, an indicator of hepatic steatosis. In a logistic regression analysis adjusted for age, gender and BMI individuals in the highest quartile of HGI exhibited a 1.6-fold increased odd of having hepatic steatosis (95% CI: 1.03-2.41; p=0.03) as compared with subjects in the lowest quartile of HGI.

CONCLUSIONS

Higher levels of HGI may identify subjects without diabetes at increased risk of having hepatic steatosis.

Low association between fasting and OGTT stimulated glucose levels with HbA1c in overweight children and adolescents

BACKGROUND

Diabetes and prediabetes are defined based on different methods such as fasting glucose, glucose at 2-hour in oral glucose tolerance test (OGTT), and glycated hemoglobin A1c (HbA1c). These parameters probably describe different deteriorations in glucose metabolism limiting the exchange between each other in definitions of diabetes.

OBJECTIVE

To investigate the relationship between OGTT and HbA1c in overweight and obese children and adolescents living in Germany.

METHODS

Study population: Overweight and obese children and adolescents (n = 4848; 2668 female) aged 7 to 17 years without known diabetes. The study population was stratified into the following subgroups: normal glucose tolerance, prediabetes, diabetes according to OGTT and/or HbA1c categories, confirmed diagnosis of diabetes.

RESULTS

In the entire study group fasting plasma glucose (FPG) correlated weakly to 2-hour glucose (r = 0.26), FPG correlated weakly to HbA1c (r = 0.18), and 2-hour glucose correlated weakly to HbA1c (r = 0.17, all P < .001). Patients with confirmed diabetes showed a very high correlation between FPG and 2-hour glucose (r = 0.73, n = 50). Moderate correlations could be found for patients with impaired fasting glucose (2-hour glucose vs HbA1c: r = 0.30, n = 436), for patients with diabetes according to OGTT and/or HbA1c (FPG vs 2-hour glucose: r = 0.43; 2-hour glucose vs HbA1c: r = -0.30, n = 115) and for patients with confirmed diabetes (2-hour glucose vs HbA1c: r = -0.47, all P < .001).

CONCLUSIONS

Because FPG, 2-hour glucose, and HbA1c correlated only weakly we propose that these parameters, particularly in the normal range, might reflect distinct aspects of carbohydrate metabolism.

Prevalence and phenotype of diabetes and prediabetes using fasting glucose vs HbA1c in a Caribbean population

BACKGROUND

Both fasting plasma glucose (FPG) and HbA1c are recommended for the diagnosis of diabetes and prediabetes by the American Diabetes Association (ADA), and for diabetes by the World Health Organization. The ADA guidance is influential on clinical practice in many developing countries, including in the Caribbean and Latin America. We aimed to compare the prevalence and characteristics of individuals identified as having diabetes and prediabetes by FPG and HbA1c in a predominantly African ancestry Caribbean population.

METHODS

A representative population-based sample of 1234 adults (≥25 years of age) resident in Barbados was recruited. Standard methods with appropriate quality control were used to collect data on height, weight, blood pressure, fasting lipids and history of diagnosed diabetes, and to measure fasting glucose and HbA1c. Those with previously diagnosed diabetes (n = 192) were excluded from the analyses. Diabetes was defined as: FPG ≥7.0 mmol/L or HbA1c ≥6.5%; prediabetes as: FPG ≥5.6 to <7mmol/L or HbA1c ≥5.7 to <6.5%.

RESULTS

Complete data were available on 939 participants without previously diagnosed diabetes. The prevalence of undiagnosed diabetes was higher, but not significantly so, by HbA1c (4.9%, 95% CI 3.5, 6.8) vs FPG (3.5%, 2.4, 5.1). Overall 79 individuals had diabetes by either measure, but only 21 on both. The prevalence of prediabetes was higher by HbA1c compared to FPG: 41.7% (37.9, 45.6) vs 15.0% (12.8, 17.5). Overall 558 individuals had prediabetes by either measure, but only 107 on both. HbA1c, but not FPG, was significantly higher in women than men; and FPG, but not HbA1c, was significantly associated with raised triglycerides and low HDL cholesterol.

CONCLUSION

The agreement between FPG and HbA1c defined hyperglycaemia is poor. In addition, there are some differences in the phenotype of those identified, and HbA1c gives a much higher prevalence of prediabetes. The routine use of HbA1c for screening and diagnosis in this population would have major implications for clinical and public health policies and resources. Given the lack of robust evidence, particularly for prediabetes, on whether intervention in the individuals identified would improve outcomes, this approach to screening and diagnosis cannot be currently recommended for this population.

Is first-trimester HbA1c useful in the diagnosis of gestational diabetes?

AIMS

To evaluate the usefulness and efficacy of first-trimester HbA1c in the diagnosis of gestational diabetes (GDM).

METHODS

Prospective observational of consecutive pregnant women. All women had a first-trimester HbA1c determination and GDM screening at 24-28weeks of pregnancy using a two-step approach. A ROC curve was drawn to determine the sensitivity and specificity of HbA1c in detecting GDM and a rule-in rule-out diagnostic algorithm was proposed. The cost of the proposed algorithm was calculated.

RESULTS

152 (13.1%) of 1195 women were diagnosed of GDM. The area under the ROC curve for HbA1c to detect GDM was 0.679 (95%CI 0.631-0.727). A rule-out threshold for HbA1c of 4.8% (29mmol/mol) had 96.7% sensitivity (95%CI 93.9-99.5), 10.1% specificity (95%CI 8.3-12.0) and a negative predictive value of 95.3% (95%CI 91.3-99.3). A rule-in value of 5.6% (38mmol/mol) had a positive predictive value of 31.6% (95%CI 24.4-38.9), 89.3% specificity (95%CI 87.4-91.2) and 32.9% sensitivity (95%CI 25.4-40.4). The low positive predictive value of the rule-in threshold precludes its use for GDM diagnosis, but could be used to identify women at high risk of GDM in whom the diagnosis can be established using a one-step approach. The overall saving of the proposed algorithm would be 6.5% of the total cost with the standard strategy.

CONCLUSIONS

A first-trimester HbA1c does not have sufficient sensitivity or specificity to diagnose GDM, although the use of a higher and lower threshold could simplify the diagnostic process by reducing the number of oral glucose tolerance test, associated costs and patient inconvenience.

Overview and Discussion of the 2017 VA/DoD Clinical Practice Guideline for the Management of Type 2 Diabetes Mellitus in Primary Care

The 2017 diabetes mellitus guidelines emphasize shared decision making, dietary changes, and HbA_1c target range for optimal control of diabetes mellitus.

Impact of common genetic determinants of Hemoglobin A1c on type 2 diabetes risk and diagnosis in ancestrally diverse populations: A transethnic genome-wide meta-analysis

BACKGROUND

Glycated hemoglobin (HbA1c) is used to diagnose type 2 diabetes (T2D) and assess glycemic control in patients with diabetes. Previous genome-wide association studies (GWAS) have identified 18 HbA1c-associated genetic variants. These variants proved to be classifiable by their likely biological action as erythrocytic (also associated with erythrocyte traits) or glycemic (associated with other glucose-related traits). In this study, we tested the hypotheses that, in a very large scale GWAS, we would identify more genetic variants associated with HbA1c and that HbA1c variants implicated in erythrocytic biology would affect the diagnostic accuracy of HbA1c. We therefore expanded the number of HbA1c-associated loci and tested the effect of genetic risk-scores comprised of erythrocytic or glycemic variants on incident diabetes prediction and on prevalent diabetes screening performance. Throughout this multiancestry study, we kept a focus on interancestry differences in HbA1c genetics performance that might influence race-ancestry differences in health outcomes.

METHODS & FINDINGS

Using genome-wide association meta-analyses in up to 159,940 individuals from 82 cohorts of European, African, East Asian, and South Asian ancestry, we identified 60 common genetic variants associated with HbA1c. We classified variants as implicated in glycemic, erythrocytic, or unclassified biology and tested whether additive genetic scores of erythrocytic variants (GS-E) or glycemic variants (GS-G) were associated with higher T2D incidence in multiethnic longitudinal cohorts (N = 33,241). Nineteen glycemic and 22 erythrocytic variants were associated with HbA1c at genome-wide significance. GS-G was associated with higher T2D risk (incidence OR = 1.05, 95% CI 1.04-1.06, per HbA1c-raising allele, p = 3 × 10-29); whereas GS-E was not (OR = 1.00, 95% CI 0.99-1.01, p = 0.60). In Europeans and Asians, erythrocytic variants in aggregate had only modest effects on the diagnostic accuracy of HbA1c. Yet, in African Americans, the X-linked G6PD G202A variant (T-allele frequency 11%) was associated with an absolute decrease in HbA1c of 0.81%-units (95% CI 0.66-0.96) per allele in hemizygous men, and 0.68%-units (95% CI 0.38-0.97) in homozygous women. The G6PD variant may cause approximately 2% (N = 0.65 million, 95% CI 0.55-0.74) of African American adults with T2D to remain undiagnosed when screened with HbA1c. Limitations include the smaller sample sizes for non-European ancestries and the inability to classify approximately one-third of the variants. Further studies in large multiethnic cohorts with HbA1c, glycemic, and erythrocytic traits are required to better determine the biological action of the unclassified variants.

CONCLUSIONS

As G6PD deficiency can be clinically silent until illness strikes, we recommend investigation of the possible benefits of screening for the G6PD genotype along with using HbA1c to diagnose T2D in populations of African ancestry or groups where G6PD deficiency is common. Screening with direct glucose measurements, or genetically-informed HbA1c diagnostic thresholds in people with G6PD deficiency, may be required to avoid missed or delayed diagnoses.

The Relationship Between Sleep Duration and Glycemic Control Among Hispanic Adults With Uncontrolled Type 2 Diabetes

Purpose

The purpose of this study was to examine the relationship between sleep duration and glycemic control in adult Hispanic patients with uncontrolled type 2 diabetes.

Methods

This cross-sectional study used baseline data from 317 Hispanic adults with uncontrolled type 2 diabetes who participated in a randomized controlled trial testing a peer support intervention to improve diabetes control. To be eligible, participants had to be 18 years or older and have A1C >7% in the 3 months prior to randomization. Glycemic control was assessed by A1C ascertained through medical chart review; higher A1C levels reflected poorer glycemic control. Sleep duration (hours/night), diabetes control behaviors, and demographics were obtained by interviewer-administered questionnaire. We used multivariable generalized linear models to estimate the association between sleep duration and glycemic control.

Results

Forty-three percent of participants reported sleeping fewer than 7 hours per night. Sleep duration (hours/night) was inversely associated with A1C levels; however, the relationship was no longer statistically significant after adjusting for insulin status.

Conclusions

Sleep duration was not significantly associated with glycemic control in this sample of Hispanic adults with uncontrolled type 2 diabetes when adjusting for insulin. Future research should continue to explore this relationship among Hispanic adults with diabetes using an objective measure of sleep duration and a larger sample of Hispanic adults with both controlled and uncontrolled type 2 diabetes to determine if these results hold true.

Haemoglobin A1c as a screening tool for type 2 diabetes and prediabetes in populations of Swedish and Middle-East ancestry

AIMS

To explore and compare sensitivity and specificity for HbA1c ≥48mmol/mol as a predictor for type 2 diabetes mellitus (T2DM) in two populations with different ethnicity and to examine the predictive value of two levels of HbA1c (≥42mmol/mol, ≥39mmol/mol) for prediabetes in these populations.

METHODS

Four cohorts were examined with an oral glucose tolerance test. (1) The MEDIM Study (n=1991 individuals of Swedish and Iraqi ancestry); (2) The Skaraborg Project (n=1327 individuals of Swedish ancestry); (3) The 4-D study (n=424 individuals of Swedish, Iraqi and Turkish ancestry); (4) The Flemingsberg study (n=212 participants of Turkish ancestry).

RESULTS

HbA1c ≥48mmol/mol had a sensitivity for T2DM of 31% and 25% respectively in individuals of Middle-East and Swedish ancestry. The positive and negative predictive value was high in both populations (70.3, 96.4 and 96.2, 97.6 respectively). Using HbA1c ≥42mmol/mol and ≥39mmol/mol as a predictor for prediabetes gave a sensitivity of 17% and 36% in individuals of Middle-East and 15% and 34% in individuals of Swedish ancestry.

CONCLUSIONS

Even if HbA1c ≥48mmol/mol is a valuable diagnostic tool, it is a blunt and insensitive tool for screening and would exclude most people with T2DM, independent of ancestry and age. HbA1c is an inefficient way to detect individuals with prediabetes.