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Ebenibo S, Edeoga C, Wan J, Dagogo-Jack S. Glucoregulatory function among African Americans and European Americans with normal or pre-diabetic hemoglobin A1c levels. Metabolism 2014; 63:767-72. [PMID: 24641885 PMCID: PMC4395121 DOI: 10.1016/j.metabol.2014.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 02/21/2014] [Accepted: 03/01/2014] [Indexed: 02/08/2023]
Abstract
OBJECTIVE A hemoglobin (Hb) A1c range of 5.7%-6.4% has been recommended for the diagnosis of prediabetes. To determine the significance of such "prediabetic" HbA1c levels, we compared glucoregulatory function in persons with HbA1c levels of 5.7%-6.4% and those with HbA1c<5.7%. METHODS We studied 280 nondiabetic adults (142 black, 138 white; mean (±SD) age 44.2±10.6 years). Each subject underwent clinical assessment, blood sampling for HbA1c measurement, and a 75-g oral glucose tolerance test at baseline. Additional assessments during subsequent outpatient visits included insulin sensitivity, using homeostasis model assessment (HOMA)-IR and the hyperinsulinemic euglycemic clamp; insulin secretion, using HOMA-B and frequently samples intravenous glucose tolerance test (FSIVGTT) and disposition index (DI); and measurement of fat mass, using DXA. RESULTS Compared to subjects with HbA1c<5.7%, persons with HbA1c levels of 5.7%-6.4% were older, and had higher body mass index (BMI) and insulin secretion but similar insulin sensitivity. When the two groups were matched in age and BMI, persons with HbA1c 5.7%-6.4% were indistinguishable from those with HbA1c <5.7% with regard to all measures of glycemia and glucoregulatory function. CONCLUSIONS Unlike glucose-defined prediabetes status, an HbA1c range of 5.7%-6.4% does not reliably identify individuals with impaired insulin action or secretion, the classical defects underlying the pathophysiology of prediabetes. Thus, HbA1c cannot validly replace blood glucose measurement in the diagnosis of prediabetes. If utilized as a screening test due to convenience, aberrant HbA1c values should be corroborated with blood glucose measurement before therapeutic intervention.
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Affiliation(s)
- Sotonte Ebenibo
- Division of Endocrinology, Diabetes and Metabolism and General Clinical Research Center, University of Tennessee Health Science Center, Memphis, TN
| | - Chimaroke Edeoga
- Division of Endocrinology, Diabetes and Metabolism and General Clinical Research Center, University of Tennessee Health Science Center, Memphis, TN
| | - Jim Wan
- Division of Endocrinology, Diabetes and Metabolism and General Clinical Research Center, University of Tennessee Health Science Center, Memphis, TN
| | - Samuel Dagogo-Jack
- Division of Endocrinology, Diabetes and Metabolism and General Clinical Research Center, University of Tennessee Health Science Center, Memphis, TN.
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Affiliation(s)
- Robert M Cohen
- Division of Endocrinology, Diabetes & Metabolism, UC Medical Center, 260 Stetson Street-Suite 4200, Cincinnati, OH 45267-0547, USA; Medical Service, Cincinnati VA Medical Center, Cincinnati, OH, USA.
| | - William H Herman
- Departments of Internal Medicine and Epidemiology, University of Michigan, Ann Arbor, MI, USA
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Siu PM, Yuen QS. Supplementary use of HbA1c as hyperglycemic criterion to detect metabolic syndrome. Diabetol Metab Syndr 2014; 6:119. [PMID: 25400701 PMCID: PMC4232661 DOI: 10.1186/1758-5996-6-119] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/27/2014] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Metabolic syndrome (MetS) refers to a cluster of cardiovascular risk factors including hyperglycemia, dyslipidemia, abdominal obesity and hypertension. An effective detection of MetS not only reflects the prediction risk of diabetes mellitus and cardiovascular diseases but also helps to plan for management strategy which could reduce the healthcare burden of the society. This study aimed to compare the use of hemoglobin A1c (HbA1c) to fasting plasma glucose (FPG) as the hyperglycemic component in MetS diagnosis. METHODS Waist circumference, blood pressure, blood triglyceride, high-density lipoprotein (HDL)-cholesterol, FPG, and HbA1c were examined in 120 Hong Kong Chinese adults with MetS and 120 without MetS. After reviewing the subject basal characteristics, 11 of them were found with undiagnosed diabetes (FPG ≧7.0 mmol/L) and were excluded for further analysis. RESULTS The most prevalent MetS components among the included subjects were elevated systolic blood pressure and central obesity. Significant correlation relationships existed between FPG and HbA1c in both subject pools diagnosed with and without MetS (p < 0.001). The diagnostic rate of MetS using HbA1c was compared to FPG by the receiver operating characteristics (ROC) analysis which suggested an area under curve of 0.807 (95% CI: 0.727 to 0.887). The agreement was 90.7% in MetS-positive group with increased FPG as one of the criterion co-existed with elevated HbA1c. If including HbA1c as an additional criterion to FPG in the MetS diagnosis, 30 more participants in MetS-negative group would be MetS-positive leading to an increase in detection rate. Furthermore, 47 subjects (38 from MetS-positive group and 9 from MetS-negative group) were found having HbA1c ≧6.5%, who would have been diagnosed with diabetes based on the diagnostic criteria implemented by the Expert Group in 2009. CONCLUSION These findings suggest that HbA1c enhances the detection of hyperglycemia for the diagnosis of MetS.
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Affiliation(s)
- Parco M Siu
- Department of Health Technology and Informatics, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong China
| | - Queenie S Yuen
- Department of Health Technology and Informatics, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong China
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Mishra N, Singh N. Blood viscosity, lipid profile, and lipid peroxidation in type-1 diabetic patients with good and poor glycemic control. NORTH AMERICAN JOURNAL OF MEDICAL SCIENCES 2013; 5:562-6. [PMID: 24251275 PMCID: PMC3818830 DOI: 10.4103/1947-2714.118925] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Background: In diabetic patients, persistent hyperglycemia and poor glycemic control cause disturbances of lipid profiles, especially an increased production of oxygen free radicals. Lipid peroxidation has been considered to be a pathogenic factor of diabetic complications in Type-1 Diabetes mellitus. Aims: The aim of the present study was to investigate the effect of glycemic control on blood viscosity, lipid profile, and lipid peroxidation in Type-1 Diabetic subjects. Materials and Methods: The study included three groups; Group-I (age-matched healthy control subjects, n = 50), Group-II (Type-1 Diabetics with good glycemic control, n = 10), and Group-III (Type-1 Diabetics with poor glycemic control, n = 15). The Type 1 diabetic patients with duration of diabetes for more than 5 years were taken. Blood samples of all subjects were analyzed for all biochemical, hematological, and oxidative stress parameters. Results: The Erythrocyte malondialdehyde level was non-significantly changed (P = NS) in group–II patients but significantly increased (P < 0.001) in group-III patients, and no significant changes were found (P = NS) in Blood viscosity of both the groups (group-II and group-III), as compared to healthy control subjects (group-I). Conclusions: Our findings suggest that the monitoring of Oxidative stress and Blood Viscosity in poorly controlled Type-1 diabetic patients may be very useful marker of diabetic complications.
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Affiliation(s)
- Neetu Mishra
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, Rajasthan, India
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Cura AJ, Carruthers A. Role of monosaccharide transport proteins in carbohydrate assimilation, distribution, metabolism, and homeostasis. Compr Physiol 2013; 2:863-914. [PMID: 22943001 DOI: 10.1002/cphy.c110024] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The facilitated diffusion of glucose, galactose, fructose, urate, myoinositol, and dehydroascorbicacid in mammals is catalyzed by a family of 14 monosaccharide transport proteins called GLUTs. These transporters may be divided into three classes according to sequence similarity and function/substrate specificity. GLUT1 appears to be highly expressed in glycolytically active cells and has been coopted in vitamin C auxotrophs to maintain the redox state of the blood through transport of dehydroascorbate. Several GLUTs are definitive glucose/galactose transporters, GLUT2 and GLUT5 are physiologically important fructose transporters, GLUT9 appears to be a urate transporter while GLUT13 is a proton/myoinositol cotransporter. The physiologic substrates of some GLUTs remain to be established. The GLUTs are expressed in a tissue specific manner where affinity, specificity, and capacity for substrate transport are paramount for tissue function. Although great strides have been made in characterizing GLUT-catalyzed monosaccharide transport and mapping GLUT membrane topography and determinants of substrate specificity, a unifying model for GLUT structure and function remains elusive. The GLUTs play a major role in carbohydrate homeostasis and the redistribution of sugar-derived carbons among the various organ systems. This is accomplished through a multiplicity of GLUT-dependent glucose sensing and effector mechanisms that regulate monosaccharide ingestion, absorption,distribution, cellular transport and metabolism, and recovery/retention. Glucose transport and metabolism have coevolved in mammals to support cerebral glucose utilization.
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Affiliation(s)
- Anthony J Cura
- Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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Nayak AU, Nevill AM, Bassett P, Singh BM. Association of glycation gap with mortality and vascular complications in diabetes. Diabetes Care 2013; 36:3247-53. [PMID: 23835697 PMCID: PMC3781552 DOI: 10.2337/dc12-1040] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE The "glycation gap" (G-gap), an essentially unproven concept, is an empiric measure of disagreement between HbA1c and fructosamine, the two indirect estimates of glycemic control. Its association with demographic features and key clinical outcomes in individuals with diabetes is uncertain. RESEARCH DESIGN AND METHODS The G-gap was calculated as the difference between measured HbA1c and a fructosamine-derived standardized predicted HbA1c in 3,182 individuals with diabetes. The G-gap's associations with demographics and clinical outcomes (retinopathy, nephropathy, macrovascular disease, and mortality) were determined. RESULTS Demographics varied significantly with G-gap for age, sex, ethnic status, smoking status, type and duration of diabetes, insulin use, and obesity. A positive G-gap was associated with retinopathy (odds ratio 1.24 [95% CI 1.01-1.52], P=0.039), nephropathy (1.55 [1.23-1.95], P<0.001), and, in a subset, macrovascular disease (1.91 [1.18-3.09], P=0.008). In Cox regression analysis, the G-gap had a "U"-shaped quadratic relationship with mortality, with both negative G-gap (1.96 [1.50-2.55], P<0.001) and positive G-gap (2.02 [1.57-2.60], P<0.001) being associated with a significantly higher mortality. CONCLUSIONS We confirm published associations of G-gap with retinopathy and nephropathy. We newly demonstrate a relationship with macrovascular and mortality outcomes and potential links to distinct subpopulations of diabetes.
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Chalew SA, McCarter RJ, Hempe JM. Biological variation and hemoglobin A1c: relevance to diabetes management and complications. Pediatr Diabetes 2013; 14:391-8. [PMID: 23952704 DOI: 10.1111/pedi.12055] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 05/08/2013] [Accepted: 05/14/2013] [Indexed: 01/10/2023] Open
Affiliation(s)
- Stuart A Chalew
- Division of Pediatric Endocrinology and Diabetes, Louisiana State University Health Sciences Center, Children's Hospital of New Orleans and the Research Institute for Children, New Orleans, LA 70118, USA.
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Clark SLD, Santin AE, Bryant PA, Holman R, Rodnick KJ. The initial noncovalent binding of glucose to human hemoglobin in nonenzymatic glycation. Glycobiology 2013; 23:1250-9. [PMID: 23926230 DOI: 10.1093/glycob/cwt061] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mechanisms for nonenzymatic protein glycation have been extensively studied albeit with an emphasis at the later stages that gives rise to advanced glycation end products. No detailed investigation of the initial, noncovalent binding of d-glucose to human hemoglobin A (HbA) exists in the literature. Although anionic molecules 2,3-bisphosphoglycerate (BPG), inorganic phosphate (Pi) and HCO3(-) have been implicated in the latter stages of glycation, their involvement at the initial binding of glucose to HbA has not yet been assessed. Results from this computational study involving crystal structures of HbA predict that the transient, ring-opened glucose isomer, assumed to be critical in the later stages of glycation, is not directly involved in initial binding to the β-chain of HbA. All the five structures of glucose generated upon mutorotation will undergo reversible, competitive and slow binding at multiple amino acid residues. The ring-opened structure is most likely generated from previously bound pyranoses that undergo mutarotation while bound. BPG, Pi and HCO3(-) also reversibly bind to HbA with similar energies as glucose isomers (~3-5 kcal/mol) and share common binding sites with glucose isomers. However, there was modest amino acid residue selectivity for binding of certain anionic molecules (1-3 regions) but limited selectivity for glucose structures (≥ 7 regions). The clinical difference between average blood glucose and predicted HbA1c, and the presence of unstable HbA-glucose complexes may be more fully explained by initial noncovalent binding interactions and different concentrations of BPG, Pi and HCO3(-) in serum vs. erythrocytes.
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Glycated hemoglobin is not an accurate indicator of glycemia in rainbow trout. Comp Biochem Physiol A Mol Integr Physiol 2013; 165:343-52. [DOI: 10.1016/j.cbpa.2013.04.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 04/14/2013] [Accepted: 04/14/2013] [Indexed: 11/16/2022]
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Zafon C, Ciudin A, Valladares S, Mesa J, Simó R. Variables involved in the discordance between HbA1c and fructosamine: the glycation gap revisited. PLoS One 2013; 8:e66696. [PMID: 23776693 PMCID: PMC3680426 DOI: 10.1371/journal.pone.0066696] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/13/2013] [Indexed: 01/09/2023] Open
Abstract
AIMS Glycation gap (GG) is defined as the difference between the measured level of HbA1c and the level that would be predicted from its regression on the fructosamine level. The aims of the study were: 1) To determine the reproducibility and consistency of GC; 2) To discover factors related to GG value. Given that metformin might increase glucose transport through the erythrocyte membrane, this treatment was also considered in the analyses of the results. METHODS GG was calculated in two blood samples separated 30.6 (SD 7.3) weeks, obtained in 508 type 2 diabetic patients. The following variables were considered: HbA1c, fructosamine, glucose, creatinine, hematological parameters and treatment with metformin. Multivariate and logistic regression analyses were performed to explore the variables independently related to CG. RESULTS GG was reproducible and consistent over time. Creatinine, mean corpuscular hemoglobin concentration (MCHC), and glycemia (inverse relationship); and HbA1c and treatment with metformin (direct relationship) were independently related to GG. Patients treated with metformin showed higher HbA1c values, despite similar fructosamine concentrations, than patients not treated with the drug. CONCLUSIONS GG is independently related to serum levels of creatinine, MCHC and treatment with metformin. The spurious effect of metformin on Hb glycation could have serious clinical implications and should be considered when interpreting the results of clinical trials.
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Affiliation(s)
- Carles Zafon
- Diabetes and Metabolism Research Unit (VHIR) and Department of Endocrinology, Hospital Vall d'Hebron and Universitat Autònoma de Barcelona, Barcelona, Spain.
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Hare MJL, Magliano DJ, Zimmet PZ, Söderberg S, Joonas N, Pauvaday V, Larhubarbe J, Tuomilehto J, Kowlessur S, Alberti KGMM, Shaw JE. Glucose-independent ethnic differences in HbA1c in people without known diabetes. Diabetes Care 2013; 36:1534-40. [PMID: 23275368 PMCID: PMC3661823 DOI: 10.2337/dc12-1210] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine whether glucose-independent differences in HbA1c exist between people of African, South Asian, and Chinese ethnicities. RESEARCH DESIGN AND METHODS Data from 6,701 people aged 19-78 years, without known diabetes, from Mauritius, and participating in the population-based Non-Communicable Disease Surveys of the main island and the island of Rodrigues were included. Participants were African (n = 1,219 from main island, n = 1,505 from Rodrigues), South Asian (n = 3,820), and Chinese (n = 157). Survey data included HbA1c, plasma glucose during oral glucose tolerance testing (OGTT), anthropometry, demographics, and medical and lifestyle history. RESULTS Mean HbA1c, after adjustment for fasting and 2-h plasma glucose and other factors known to influence HbA1c, was higher in Africans from Rodrigues (6.1%) than in South Asians (5.7%, P < 0.001), Chinese (5.7%, P < 0.001), or Africans from the main island of Mauritius (5.7%, P < 0.001). The age-standardized prevalence of diabetes among Africans from Rodrigues differed substantially depending on the diagnostic criteria used [OGTT 7.9% (95% CI 5.8-10.0); HbA1c 17.3% (15.3-19.2)]. Changing diagnostic criteria resulted in no significant change in the prevalence of diabetes within the other ethnic groups. CONCLUSIONS People of African ethnicity from Rodrigues have higher HbA1c than those of South Asian or African ethnicity from the main island of Mauritius for reasons not explained by plasma glucose during an OGTT or traditional factors known to affect glycemia. Further research should be directed at determining the mechanism behind this disparity and its relevance to clinical outcomes.
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Cosson E, Chiheb S, Cussac-Pillegand C, Banu I, Hamo-Tchatchouang E, Nguyen MT, Aout M, Charnaux N, Valensi P. Haemoglobin glycation may partly explain the discordance between HbA1c measurement and oral glucose tolerance test to diagnose dysglycaemia in overweight/obese subjects. DIABETES & METABOLISM 2013; 39:118-25. [DOI: 10.1016/j.diabet.2012.08.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/19/2012] [Accepted: 08/01/2012] [Indexed: 11/27/2022]
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Abstract
HbA1c has become the gold standard for monitoring glycemic control in patients with diabetes mellitus. The use of this test has been expanded to diagnose and screen for diabetes mellitus with the endorsement of influential diabetes societies and the World Health Organization. The literature on the use of HbA1c for the diagnosis and screening of diabetes mellitus was critically examined. There is substantial recent literature on this topic with strong advocates for the use of HbA1c to diagnose and screen for diabetes and equally strong detractors for its use. Advocates of the use of HbA1c cite challenges in respect of patient compliance and the analysis of glucose and inconsistency of diagnosis with glucose-based diabetes diagnosis with the elimination or reduction in these challenges in HbA1c-based diagnosis. Detractors of its use cite increased cost, concerns about the availability of HbA1c testing, and the influence of demographic and clinical factors on HbA1c results that make the use of a single-threshold values questionable for different ethnic and age groups. Despite the recommendation of many international diabetes societies that HbA1c be used for screening and diagnosis of diabetes mellitus, there is a wide divergence of opinion on this use.
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Affiliation(s)
- Trefor Higgins
- DynaLIFEDx, #200, 10150 102 St, Edmonton, AB, T6L 1X2, Canada.
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Lledó-García R, Mazer NA, Karlsson MO. A semi-mechanistic model of the relationship between average glucose and HbA1c in healthy and diabetic subjects. J Pharmacokinet Pharmacodyn 2013; 40:129-42. [PMID: 23307170 DOI: 10.1007/s10928-012-9289-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 12/11/2012] [Indexed: 11/29/2022]
Abstract
HbA1c is the most commonly used biomarker for the adequacy of glycemic management in diabetic patients and a surrogate endpoint for anti-diabetic drug approval. In spite of an empirical description for the relationship between average glucose (AG) and HbA1c concentrations, obtained from the A1c-derived average glucose (ADAG) study by Nathan et al., a model for the non-steady-state relationship is still lacking. Using data from the ADAG study, we here develop such models that utilize literature information on (patho)physiological processes and assay characteristics. The model incorporates the red blood cell (RBC) aging description, and uses prior values of the glycosylation rate constant (KG), mean RBC life-span (LS) and mean RBC precursor LS obtained from the literature. Different hypothesis were tested to explain the observed non-proportional relationship between AG and HbA1c. Both an inverse dependence of LS on AG and a non-specificity of the National Glycohemoglobin Standardization Program assay used could well describe the data. Both explanations have mechanistic support and could be incorporated, alone or in combination, in models allowing prediction of the time-course of HbA1c changes associated with changes in AG from, for example dietary or therapeutic interventions, and vice versa, to infer changes in AG from observed changes in HbA1c. The selection between the alternative mechanistic models require gathering of new information.
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Affiliation(s)
- Rocío Lledó-García
- Pharmacometrics Research Group, Department of Pharmaceutical Biosciences, Uppsala University, Box 591, SE 751 24, Uppsala, Sweden.
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Ma H, Xu C, Xu L, Yu C, Miao M, Li Y. Independent association of HbA1c and nonalcoholic fatty liver disease in an elderly Chinese population. BMC Gastroenterol 2013; 13:3. [PMID: 23294935 PMCID: PMC3543719 DOI: 10.1186/1471-230x-13-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 12/14/2012] [Indexed: 01/07/2023] Open
Abstract
Background To investigate the association between serum glycosylated hemoglobin (HbA1c) levels and nonalcoholic fatty liver disease (NAFLD) in an elderly Chinese population. Methods A cross-sectional study was performed among the 949 retired elderly employees of Zhenhai Refining & Chemical Company Ltd., Ningbo, China. Results A total of 257 (27.08%) subjects fulfilled the diagnostic criteria of NAFLD, and NAFLD patients had significantly higher serum HbA1c levels than controls (P <0.001). The prevalence of NAFLD was significantly higher in subjects with increased serum HbA1c level (HbA1c ≥6.5%) than in those with normal range of serum HbA1c level (51.71% vs. 25.20%; P <0.001), and the prevalence increased along with progressively higher serum HbA1c levels (P for trend <0.001). Stepwise logistic regression analysis showed that serum HbA1c level was significantly associated with the risk for NAFLD (odds ratio: 1.547, 95% confidence interval: 1.054 – 2.270; P =0.026). Conclusions Our results suggest that serum HbA1c level is associated with NAFLD, and increased serum HbA1c level is an independent risk factor for NAFLD in elderly Chinese.
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Affiliation(s)
- Han Ma
- Department of Gastroenterology, the First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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Mosca A, Lapolla A, Gillery P. Glycemic control in the clinical management of diabetic patients. Clin Chem Lab Med 2013; 51:753-66. [DOI: 10.1515/cclm-2012-0594] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 11/07/2012] [Indexed: 11/15/2022]
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Cohen RM, Lindsell CJ. When the blood glucose and the HbA(1c) don't match: turning uncertainty into opportunity. Diabetes Care 2012; 35:2421-3. [PMID: 23173128 PMCID: PMC3507598 DOI: 10.2337/dc12-1479] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Robert M Cohen
- Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
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Chapp-Jumbo E, Edeoga C, Wan J, Dagogo-Jack S. Ethnic disparity in hemoglobin A1c levels among normoglycemic offspring of parents with type 2 diabetes mellitus. Endocr Pract 2012; 18:356-62. [PMID: 22138077 DOI: 10.4158/ep11245.or] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To investigate the racial/ethnic disparities in hemoglobin A1c levels among nondiabetic persons with similar parental history of type 2 diabetes mellitus. METHODS We studied a community-based sample of adult offspring of parents with type 2 diabetes mellitus. Measurements included anthropometry, hematology assessments, serial fasting plasma glucose, oral glucose tolerance testing, plasma insulin, hemoglobin A1c, insulin sensitivity, and β-cell function, using a homeostasis model assessment. RESULTS The study included 302 participants (135 white, 167 black). Compared with white participants, black participants had lower fasting plasma glucose levels (91.9 ± 0.51 mg/dL vs 93.6 ± 0.50 mg/dL, P = .015), lower area under the curve of plasma glucose during oral glucose tolerance testing (P = <.001), higher body mass index (31.1 ± 0.61 kg/m² vs 28.5 ± 0.57 kg/m², P = <.001), and similar insulin sensitivity and β-cell function. Hemoglobin A1c was higher in black participants than in white participants (5.68 ± 0.033% vs 5.45 ± 0.028%, P<.001). The absolute black-white difference in hemoglobin A1c level of approximately 0.22% persisted after adjusting for age, hemoglobin, hematocrit, body mass index, waist circumference, fasting plasma glucose, glucose area under the curve, and other covariates. CONCLUSIONS Among healthy offspring of parents with type 2 diabetes mellitus in this study, African American participants had higher hemoglobin A1c levels than white participants after adjusting for age, adiposity, blood glucose, and known variables. Thus, plasma glucose level is more valid than hemoglobin A1c for diagnosing prediabetes or diabetes in black persons.
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Affiliation(s)
- Emmanuel Chapp-Jumbo
- Division of Endocrinology, Diabetes, and Metabolism, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Higgins T. HbA1c — An analyte of increasing importance. Clin Biochem 2012; 45:1038-45. [DOI: 10.1016/j.clinbiochem.2012.06.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 06/04/2012] [Accepted: 06/06/2012] [Indexed: 11/29/2022]
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Affiliation(s)
- Silvio E Inzucchi
- Section of Endocrinology, Yale University School of Medicine, New Haven, CT 06520, USA.
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Yang W, Fu J, Yu M, Huang Q, Wang D, Xu J, Deng Q, Yao P, Huang F, Liu L. Effects of flaxseed oil on anti-oxidative system and membrane deformation of human peripheral blood erythrocytes in high glucose level. Lipids Health Dis 2012; 11:88. [PMID: 22768971 PMCID: PMC3459705 DOI: 10.1186/1476-511x-11-88] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 06/25/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The erythrocyte membrane lesion is a serious diabetic complication. A number of studies suggested that n-3 fatty acid could reduce lipid peroxidation and elevate α- or γ-tocopherol contents in membrane of erythrocytes. However, evidence regarding the protective effects of flaxseed oil, a natural product rich in n-3 fatty acid, on lipid peroxidation, antioxidative capacity and membrane deformation of erythrocytes exposed to high glucose is limited. METHODS Human peripheral blood erythrocytes were isolated and treated with 50 mM glucose to mimic hyperglycemia in the absence or presence of three different doses of flaxseed oil (50, 100 or 200 μM) in the culture medium for 24 h. The malondialdehyde (MDA) and L-glutathione (GSH) were measured by HPLC and LC/MS respectively. The phospholipids symmetry and membrane fatty acid composition of human erythrocytes were detected by flow cytometry and gas chromatograph (GC). The morphology of human erythrocyte was illuminated by ultra scanning electron microscopy. RESULTS Flaxseed oil attenuated hyperglycemia-induced increase of MDA and decrease of GSH in human erythrocytes. Human erythrocytes treated with flaxseed oil contained higher C22:5 and C22:6 than those in the 50 mM glucose control group, indicating that flaxseed oil could reduce lipid asymmetric distribution and membrane perturbation. The ultra scanning electron microscopy and flow cytometer have also indicated that flaxseed oil could protect the membrane of human erythrocytes from deformation at high glucose level. CONCLUSION The flaxseed oil supplementation may prevent lipid peroxidation and membrane dysfunction of human erythrocytes in hyperglycemia.
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Affiliation(s)
- Wei Yang
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, China
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72
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Herman WH, Cohen RM. Racial and ethnic differences in the relationship between HbA1c and blood glucose: implications for the diagnosis of diabetes. J Clin Endocrinol Metab 2012; 97:1067-72. [PMID: 22238408 PMCID: PMC3319188 DOI: 10.1210/jc.2011-1894] [Citation(s) in RCA: 201] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hemoglobin A1c (HbA1c) is widely used as an index of mean glycemia in diabetes, as a measure of risk for the development of diabetic complications, and as a measure of the quality of diabetes care. In 2010, the American Diabetes Association recommended that HbA1c tests, performed in a laboratory using a method certified by the National Glycohemoglobin Standardization Program, be used for the diagnosis of diabetes. Although HbA1c has a number of advantages compared to traditional glucose criteria, it has a number of disadvantages. Hemoglobinopathies, thalassemia syndromes, factors that impact red blood cell survival and red blood cell age, uremia, hyperbilirubinemia, and iron deficiency may alter HbA1c test results as a measure of average glycemia. Recently, racial and ethnic differences in the relationship between HbA1c and blood glucose have also been described. Although the reasons for racial and ethnic differences remain unknown, factors such as differences in red cell survival, extracellular-intracellular glucose balance, and nonglycemic genetic determinants of hemoglobin glycation are being explored as contributors. Until the reasons for these differences are more clearly defined, reliance on HbA1c as the sole, or even preferred, criterion for the diagnosis of diabetes creates the potential for systematic error and misclassification. HbA1c must be used thoughtfully and in combination with traditional glucose criteria when screening for and diagnosing diabetes.
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Affiliation(s)
- William H Herman
- University of Michigan, 1000 Wall Street, Room 6100/SPC 5714, Ann Arbor, Michigan 48105-1912, USA.
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73
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Hardikar PS, Joshi SM, Bhat DS, Raut DA, Katre PA, Lubree HG, Jere A, Pandit AN, Fall CHD, Yajnik CS. Spuriously high prevalence of prediabetes diagnosed by HbA(1c) in young indians partly explained by hematological factors and iron deficiency anemia. Diabetes Care 2012; 35:797-802. [PMID: 22323413 PMCID: PMC3308281 DOI: 10.2337/dc11-1321] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To examine the influence of glycemic and nonglycemic parameters on HbA(1c) concentrations in young adults, the majority of whom had normal glucose tolerance. RESEARCH DESIGN AND METHODS We compared the diagnosis of normal glucose tolerance, prediabetes, and diabetes between a standard oral glucose tolerance test (OGTT; World Health Organization 2006 criteria) and HbA(1c) concentrations (American Diabetes Association [ADA] 2009 criteria) in 116 young adults (average age 21.6 years) from the Pune Children's Study. We also studied the contribution of glycemic and nonglycemic determinants to HbA(1c) concentrations. RESULTS The OGTT showed that 7.8% of participants were prediabetic and 2.6% were diabetic. By ADA HbA(1c) criteria, 23.3% were prediabetic and 2.6% were diabetic. The negative predictive value of HbA(1c) was 93% and the positive predictive value was 20% (only 20% had prediabetes or diabetes according to the OGTT; this figure was 7% in anemic participants). Of participants, 34% were anemic, 37% were iron deficient (ferritin <15 ng/mL), 40% were vitamin B(12) deficient (<150 pmol/L), and 22% were folate deficient (<7 nmol/L). On multiple linear regression analysis, HbA(1c) was predicted by higher 2-h glucose (R(2) = 25.6%) and lower hemoglobin (R(2) = 7.7%). When hematological parameters were replaced by ferritin, vitamin B(12), and folate, HbA(1c) was predicted by higher glycemia (R(2) = 25.6%) and lower ferritin (R(2) = 4.3%). CONCLUSIONS The use of HbA(1c) to diagnose prediabetes and diabetes in iron-deficient populations may lead to a spuriously exaggerated prevalence. Further investigation is required before using HbA(1c) as a screening tool in nutritionally compromised populations.
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Affiliation(s)
- Pallavi S Hardikar
- Bajaj Diabetology Research Centre, King Edward Memorial Hospital Research Centre, Pune, India
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74
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Lyons TJ, Basu A. Biomarkers in diabetes: hemoglobin A1c, vascular and tissue markers. Transl Res 2012; 159:303-12. [PMID: 22424433 PMCID: PMC3339236 DOI: 10.1016/j.trsl.2012.01.009] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 01/08/2012] [Accepted: 01/09/2012] [Indexed: 12/19/2022]
Abstract
Biomarkers are conventionally defined as "biological molecules that represent health and disease states." They typically are measured in readily available body fluids (blood or urine), lie outside the causal pathway, are able to detect subclinical disease, and are used to monitor clinical and subclinical disease burden and response to treatments. Biomarkers can be "direct" endpoints of the disease itself, or "indirect" or surrogate endpoints. New technologies (such as metabolomics, proteomics, genomics) bring a wealth of opportunity to develop new biomarkers. Other new technologies enable the development of nonmolecular, functional, or biophysical tissue-based biomarkers. Diabetes mellitus is a complex disease affecting almost every tissue and organ system, with metabolic ramifications extending far beyond impaired glucose metabolism. Biomarkers may reflect the presence and severity of hyperglycemia (ie, diabetes itself) or the presence and severity of the vascular complications of diabetes. Illustrative examples are considered in this brief review. In blood, hemoglobin A1c (HbA1c) may be considered as a biomarker for the presence and severity of hyperglycemia, implying diabetes or prediabetes, or, over time, as a "biomarker for a risk factor," ie, hyperglycemia as a risk factor for diabetic retinopathy, nephropathy, and other vascular complications of diabetes. In tissues, glycation and oxidative stress resulting from hyperglycemia and dyslipidemia lead to widespread modification of biomolecules by advanced glycation end products (AGEs). Some of these altered species may serve as biomarkers, whereas others may lie in the causal pathway for vascular damage. New noninvasive technologies can detect tissue damage mediated by AGE formation: these include indirect measures such as pulse wave analysis (a marker of vascular dysfunction) and more direct markers such as skin autofluorescence (a marker of long-term accumulation of AGEs). In the future, we can be optimistic that new blood and tissue-based biomarkers will enable the detection, prevention, and treatment of diabetes and its complications long before overt disease develops.
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Affiliation(s)
- Timothy J Lyons
- Harold Hamm Diabetes Center and Section of Endocrinology and Diabetes, University of Oklahoma Health Sciences Center, 1000 N. Lincoln Blvd., Oklahoma City, OK 73104-5020, USA.
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75
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Abstract
Haemoglobin A(1c) (HbA(1c)) has recently been adopted by the World Health Organization into its recommended criteria for diabetes diagnosis. Much debate continues regarding the relative benefits and potential disadvantages surrounding the use of HbA(1c) for this purpose. There is a lack of consensus as to whether this alteration to the definition of diabetes is a step forward or whether it could add further confusion and ambiguity to the debate on the method and criteria for the diagnosis of this globally important disease. This review provides a comprehensive overview of the current issues surrounding how HbA(1c) is measured and reported; and of the evidence for and against its use in diagnosis.
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Affiliation(s)
- M J L Hare
- Baker IDI Heart and Diabetes Institute, Melbourne, Vic., Australia.
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76
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Hinzmann R, Schlaeger C, Tran CT. What do we need beyond hemoglobin A1c to get the complete picture of glycemia in people with diabetes? Int J Med Sci 2012; 9:665-81. [PMID: 23055818 PMCID: PMC3465850 DOI: 10.7150/ijms.4520] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 08/19/2012] [Indexed: 02/06/2023] Open
Abstract
Hemoglobin A1c (HbA1c) is currently the most commonly used marker for the determination of the glycemic status in people with diabetes and it is frequently used to guide therapy and especially medical treatment of people with diabetes. The measurement of HbA1c has reached a high level of analytical quality and, therefore, this biomarker is currently also suggested to be used for the diagnosis of diabetes. Nevertheless, it is crucial for people with diabetes and their treating physicians to be aware of possible interferences during its measurement as well as physiological or pathological factors that contribute to the HbA1c concentration without being related to glycemia, which are discussed in this review. We performed a comprehensive review of the literature based on PubMed searches on HbA1c in the treatment and diagnosis of diabetes including its most relevant limitations, glycemic variability and self-monitoring of blood glucose (SMBG). Although the high analytical quality of the HbA1c test is widely acknowledged, the clinical relevance of this marker regarding risk reduction of cardiovascular morbidity and mortality is still under debate. In this respect, we argue that glycemic variability as a further risk factor should deserve more attention in the treatment of diabetes.
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77
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Neuhold S, Resl M, Huelsmann M, Strunk G, Adlbrecht C, Rath C, Prager R, Luger A, Clodi M, Pacher R. Repeat measurements of glycated haemoglobin A(1c) and N-terminal pro-B-type natriuretic peptide: divergent behaviour in diabetes mellitus. Eur J Clin Invest 2011; 41:1292-8. [PMID: 21615391 DOI: 10.1111/j.1365-2362.2011.02539.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Patients with diabetes mellitus have a substantially increased risk of developing cardiovascular disease. However, the absolute risk greatly varies not only among patients, but the risk profile for an individual patient may also change over time. We investigated the prognostic role of repetitive measurements of Glycated haemoglobin A(1c) (HbA(1c) ) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with longstanding diabetes. MATERIALS AND METHODS For this prospective, observational study data from 544 consecutive patients were collected between 2005 and 2008. HbA(1c) and NT-proBNP were measured at baseline and after 1 year. The median observation period was 40 months. Endpoints were all-cause mortality, cardiac, cardiovascular and all-cause hospitalizations. RESULTS N-terminal pro-B-type natriuretic peptide concentrations significantly increased from 230 ± 385 to 280 ± 449 pg mL(-1) (P < 0·001); during the same time, HbA(1c) significantly decreased from 7·6 ± 1·5 to 7·3 ± 1·2 (P < 0·001). NT-proBNP was the best baseline predictor in a Cox regression model consisting of NT-proBNP, HbA(1c) , age, gender and duration of diabetes for all endpoints (P < 0·001). NT-proBNP at follow-up was the best predictor for the remaining period (P < 0·001, all endpoints). HbA(1c) at baseline and follow-up was predictive for all-cause hospitalizations (P = 0·005 both). In a third model that investigated the plasticity of both markers, changes in HbA(1c) concentration had no predictive value, but a change of NT-proBNP concentration was highly predictive (P = 0·025 all-cause mortality, P < 0·001 all other endpoints). CONCLUSIONS N-terminal pro-B-type natriuretic peptide and HbA(1c) concentrations significantly diverged over a 1-year period. NT-proBNP was the most potent predictor of outcome at baseline and follow-up, and changes in NT-proBNP concentrations were linked to an altered risk profile, unlike changes in HbA(1c) levels.
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Affiliation(s)
- Stephanie Neuhold
- Division of Cardio-Thoracic-Vascular Anaesthesia and Intensive Care Medicine, Department of Anaesthesia, General Intensive Care and Pain Medicine, Medical University Vienna, Austria
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78
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Nayak AU, Holland MR, Macdonald DR, Nevill A, Singh BM. Evidence for consistency of the glycation gap in diabetes. Diabetes Care 2011; 34:1712-6. [PMID: 21715524 PMCID: PMC3142043 DOI: 10.2337/dc10-1767] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Discordance between HbA(1c) and fructosamine estimations in the assessment of glycemia is often encountered. A number of mechanisms might explain such discordance, but whether it is consistent is uncertain. This study aims to coanalyze paired glycosylated hemoglobin (HbA(1c))-fructosamine estimations by using fructosamine to determine a predicted HbA(1c), to calculate a glycation gap (G-gap) and to determine whether the G-gap is consistent over time. RESEARCH DESIGN AND METHODS We included 2,263 individuals with diabetes who had at least two paired HbA(1c)-fructosamine estimations that were separated by 10 ± 8 months. Of these, 1,217 individuals had a third pair. The G-gap was calculated as G-gap = HbA(1c) minus the standardized fructosamine-derived HbA(1c) equivalent (FHbA(1c)). The hypothesis that the G-gap would remain consistent in individuals over time was tested. RESULTS The G-gaps were similar in the first, second, and third paired samples (0.0 ± 1.2, 0.0 ± 1.3, and 0.0 ± 1.3, respectively). Despite significant changes in the HbA(1c) and fructosamine, the G-gap did not differ in absolute or relative terms and showed no significant within-subject variability. The direction of the G-gap remained consistent. CONCLUSIONS The G-gap appears consistent over time; thus, by inference any key underlying mechanisms are likely to be consistent. G-gap calculation may be a method of exploring and evaluating any such underlying mechanisms.
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Affiliation(s)
- Ananth U Nayak
- Wolverhampton Diabetes Centre, New Cross Hospital, Wolverhampton, UK.
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79
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Lapolla A, Mosca A, Fedele D. The general use of glycated haemoglobin for the diagnosis of diabetes and other categories of glucose intolerance: still a long way to go. Nutr Metab Cardiovasc Dis 2011; 21:467-475. [PMID: 21641782 DOI: 10.1016/j.numecd.2011.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 01/31/2011] [Accepted: 02/06/2011] [Indexed: 12/16/2022]
Abstract
Glycated haemoglobin (HbA(1c)) is considered the 'gold standard' for monitoring metabolic control in diabetes. An International Expert Committee recently recommended HbA(1c) as a better method than measurement of glucose to use in the diagnosis of diabetes, based on its strong association with microvascular complications, a lower day-to-day variability and ease of use, not necessarily in the fasting state. These recommendations have been embraced by the American Diabetes Association (ADA), which stated in its Standards of Medical Care in Diabetes 2010 that "A(1c), fasting plasma glucose or the 2 h 75 g oral glucose tolerance test (OGTT) are appropriate for testing diabetes and assessing the risk of future diabetes," and that "a confirmed A(1c) ≥ 6.5% is diagnostic for diabetes." Measuring HbA(1c) has several advantages over glucose measurements, but its exclusive use should only be considered if the test is conducted under standardised conditions and its limitations are taken into due account. The impact of its use on the epidemiology of diabetes and other categories of glucose intolerance, as seen from recent reports, is also discussed.
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Affiliation(s)
- A Lapolla
- Dipartimento di Scienze Mediche e Chirurgiche, Cattedra di Malattie del Metabolismo, Università degli Studi di Padova, Padova, Italy.
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Diagnosing diabetes with A1C: implications and considerations for measurement and surrogate markers. Nurse Pract 2010; 35:16-23; quiz 23-4. [PMID: 20827232 DOI: 10.1097/01.npr.0000388206.16357.02] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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81
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Rodríguez-Segade S, Rodríguez J, Cabezas-Agricola JM, Casanueva FF, Camiña F. Progression of nephropathy in type 2 diabetes: the glycation gap is a significant predictor after adjustment for glycohemoglobin (Hb A1c). Clin Chem 2010; 57:264-71. [PMID: 21147957 DOI: 10.1373/clinchem.2010.144949] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND The glycation gap has been proposed as an index of nonglycemic determinants of glycated hemoglobin (Hb A(1c)). We investigated whether it predicts progression of nephropathy in type 2 diabetic patients. METHODS We recorded albumin excretion rate, Hb A(1c), and serum fructosamine in 2314 patients over an average of 6.5 years. Hb A(1c) was regressed on fructosamine by using a repeated-measures longitudinal regression model and data for all visits of all patients; the raw glycation gap gg was calculated at each visit, as measured by Hb A(1c) minus the value predicted by the regression; and the mean glycation gap (GG) was defined for each patient as the mean of the values for the raw glycation gap (gg) calculated at each visit. The study group was divided into high-, medium- and low-GG groups of equal sizes, which were compared for progression of nephropathy by Cox regression analyses controlling for age, sex, duration of diabetes, initial nephropathy status, therapy, baseline Hb A(1c), mean Hb A(1c), and mean fructosamine. The design of the study was a retrospective cohort study with follow-up for 6.5 (SD 4.2) years. RESULTS The gg exhibited considerable stability over time. In the high- and medium-GG groups, the risk of progression of nephropathy was respectively 2.5 and 1.6 times that of the low-GG group (P < 0.0001 and P = 0.001, respectively) after adjustment as described above. CONCLUSIONS GG predicts the progression of nephropathy in type 2 diabetic patients independently of fructosamine and even after adjustment for Hb A(1c). The joint use of the glycation gap and fructosamine as measures of nonglycemic and glycemic determinants of glycation, respectively, may improve evaluation of the risk of nephropathy and of the glycemic control desirable for the individual patient.
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Affiliation(s)
- Santiago Rodríguez-Segade
- Department of Biochemistry and Molecular Biology, University of Santiago de Compostela, Santiago de Compostela, Spain.
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82
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Cohen RM, Haggerty S, Herman WH. HbA1c for the diagnosis of diabetes and prediabetes: is it time for a mid-course correction? J Clin Endocrinol Metab 2010; 95:5203-6. [PMID: 21131541 PMCID: PMC2999978 DOI: 10.1210/jc.2010-2352] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Soros AA, Chalew SA, McCarter RJ, Shepard R, Hempe JM. Hemoglobin glycation index: a robust measure of hemoglobin A1c bias in pediatric type 1 diabetes patients. Pediatr Diabetes 2010; 11:455-61. [PMID: 20088859 DOI: 10.1111/j.1399-5448.2009.00630.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The hemoglobin glycation index (HGI) assesses biological variation in A1c after accounting for the effect of mean blood glucose (MBG). Previous studies minimized analytical variation that could mask biological variation and showed that HGI was consistent within individuals over time and positively associated with risk for microvascular complications. We tested the hypothesis that biological variation in A1c can be assessed by HGI calculated using routine MBG and A1c data obtained from a typical diabetes clinic. METHODS Self-monitored MBG and A1c were collected from charts of 202 pediatric type 1 diabetes patients attending 1612 clinic visits over 6 yr. Predicted A1c was calculated from the linear regression equation of A1c on MBG in the study population. HGI was calculated by subtracting predicted A1c from observed A1c. Patients were divided into low, moderate, and high HGI tertile groups. RESULTS Patients used 12 models of glucose meters. Download protocols varied with clinical practice over time. A1c was measured by multiple assays and laboratories. Despite this analytical heterogeneity, HGI was significantly different between individuals and correlated within individuals. MBG (mean ± SD, mg/dL) was similar in the low (186 ± 31), moderate (195 ± 28), and high (199 ± 42) HGI groups. A1c (%) was significantly different (p < 0.0001) in the low (7.6 ± 0.7), moderate (8.4 ± 0.7), and high (9.6 ± 1.1) HGI groups. CONCLUSION Biological variation in A1c is a robust quantitative trait that can be assessed using HGI calculated from routine clinic data. This suggests that HGI could be used clinically for more personalized assessment of complications risk.
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Affiliation(s)
- Arlette A Soros
- Department of Pediatrics, Louisiana State University Health Sciences Center, New Orleans, LA, USA
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84
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Abstract
The purpose of a diagnostic test is to identify individuals who have a disorder and reassure those who do not. An HbA₁(c)-based diagnosis of diabetes mellitus or prediabetes fails to meet that purpose. Diabetes mellitus is a disorder of glucose, not HbA₁(c), metabolism. Microvascular complications in diabetes mellitus are driven by chronic hyperglycemia. The correlation of these complications with HbA₁(c) levels is convenient; however, unlike the direct information provided by glucose, HbA₁(c) values reflect glycemic and nonglycemic factors. The latter include modulators of glucose transport across the erythrocyte membrane, intracellular protein glycation and deglycation, erythrocyte turnover, systemic illness and hematological and medical disorders, among others. Genetic rather than glycemic factors explain most of the variance in HbA₁(c) levels. Finally, HbA₁(c) values are misleading as a measure of average blood glucose among persons of African, Asian, Hispanic and other non-European ancestry. Given the numerous pitfalls, the use of HbA₁(c) levels for diagnosing diabetes mellitus or prediabetes is ill-advised.
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85
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Chalew SA, McCarter RJ, Ory-Ascani J, Hempe JM. Labile A1C is inversely correlated with the hemoglobin glycation index in children with type 1 diabetes. Diabetes Care 2010; 33:273-4. [PMID: 19918006 PMCID: PMC2809262 DOI: 10.2337/dc08-2220] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE We hypothesized that labile A1C (LA1C) is directly correlated with stable A1C (SA1C) and between-patient differences in SA1C, which are independent of mean blood glucose (MBG). RESEARCH DESIGN AND METHODS We measured SA1C, LA1C, MBG, and a single clinic capillary glucose (CCG) from 152 pediatric patients with type 1 diabetes. Patients were grouped as high, moderate, or low glycators by hemoglobin glycation index (HGI). RESULTS LA1C and SA1C were correlated with CCG and MBG. LA1C was not correlated with SA1C (r = 0.06, P = 0.453). LA1C level was significantly associated with glycator group status (P < 0.0019) and CCG (P < 0.0001). Adjusted LA1C levels were highest in the low-HGI patients and lowest in the high-HGI group. CONCLUSIONS A conventional model of SA1C being directly correlated with LA1C concentration was not confirmed. Between-patient differences in SA1C at the same MBG may be due to complex intracellular factors influencing formation of SA1C from LA1C.
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Affiliation(s)
- Stuart A Chalew
- Division of Pediatric Endocrinology, Department of Pediatrics, Louisiana State University Health Sciences Center and the Children's Hospital of New Orleans, New Orleans, Louisiana, USA.
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van 't Riet E, Alssema M, Rijkelijkhuizen JM, Kostense PJ, Nijpels G, Dekker JM. Relationship between A1C and glucose levels in the general Dutch population: the new Hoorn study. Diabetes Care 2010; 33:61-6. [PMID: 19808928 PMCID: PMC2797987 DOI: 10.2337/dc09-0677] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To investigate the relationship among A1C, fasting plasma glucose (FPG), and 2-h postload plasma glucose in the Dutch general population and to evaluate the results of using A1C for screening and diagnosis of diabetes. RESEARCH DESIGN AND METHODS In 2006-2007, 2,753 participants of the New Hoorn Study, aged 40-65 years, who were randomly selected from the population of Hoorn, the Netherlands, underwent an oral glucose tolerance test (OGTT). Glucose status (normal glucose metabolism [NGM], intermediate hyperglycemia, newly diagnosed diabetes, and known diabetes) was defined by the 2006 World Health Organization criteria. Spearman correlations were used to investigate the agreement between markers of hyperglycemia, and a receiver operating characteristic (ROC) curve was calculated to evaluate the use of A1C to identify newly diagnosed diabetes. RESULTS In the total population, the correlations between fasting plasma glucose and A1C and between 2-h postload plasma glucose and A1C were 0.46 and 0.33, respectively. In patients with known diabetes, these correlations were 0.71 and 0.79. An A1C level of > or =5.8%, representing 12% of the population, had the highest combination of sensitivity (72%) and specificity (91%) for identifying newly diagnosed diabetes. This cutoff point would identify 72% of the patients with newly diagnosed diabetes and include 30% of the individuals with intermediate hyperglycemia. CONCLUSIONS In patients with known diabetes, correlations between glucose and A1C are strong; however, moderate correlations were found in the general population. In addition, based on the diagnostic properties of A1C defined by ROC curve analysis, the advantage of A1C compared with OGTT for the diagnosis of diabetes is limited.
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Affiliation(s)
- Esther van 't Riet
- EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
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88
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Elleri D, Acerini CL, Allen JM, Larsen AMF, Wilinska ME, Dunger DB, Hovorka R. Effect of delay on measurement of blood glucose levels in young subjects with type 1 diabetes. Diabetes Res Clin Pract 2009; 86:e31-3. [PMID: 19643507 DOI: 10.1016/j.diabres.2009.06.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 06/20/2009] [Accepted: 06/29/2009] [Indexed: 11/18/2022]
Abstract
We investigated the effect of a 3-h time-lag between blood sampling and glucose measurement in type 1 diabetes. Blood glucose decreased by 0.47 mmol/L despite samples being collected in fluoride tubes and placed on ice. The extent of reduction differs among subjects, prevailing blood glucose and time-of-day of sample withdrawal.
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Affiliation(s)
- Daniela Elleri
- Department of Paediatrics, University of Cambridge, Hills Road, Cambridge CB2 0QQ, UK
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Leslie RDG, Cohen RM. Biologic variability in plasma glucose, hemoglobin A1c, and advanced glycation end products associated with diabetes complications. J Diabetes Sci Technol 2009; 3:635-43. [PMID: 20144305 PMCID: PMC2769979 DOI: 10.1177/193229680900300403] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Plasma glucose plays a key role in the complications of diabetes mellitus. Hemoglobin A1c (HbA1c) and circulating concentrations of advanced glycation end products (AGEs) are central to diabetes clinical care and pathophysiology. However, there is evidence for variation between individuals in the relationship of plasma glucose to both these measures and to specific complications. The glycation gap (GG) and hemoglobin glycation index represent tools for quantitating the variability in the relationship between plasma glucose and HbA1c useful for identification of underlying mechanisms. Recent evidence demonstrates the heritability of HbA1c, the GG, and AGEs, yet not of glycated serum proteins. There has been tremendous effort devoted to identifying the heritable basis of types 1 and 2 diabetes; however, studies on the heritable contributors to these mediators of glucose effect on complications are only beginning. New evidence for normal biologic variation in the distribution of glucose into the red blood cell (RBC) intracellular compartment and RBC lifespan in people with and without diabetes represent candidates for heritable mechanisms and contributors to the rise in HbA1c with age. Taken as a whole, genetic and mechanistic evidence suggests new potential targets for complications prevention and improvement in complications risk estimation. These observations could help tilt the risk-benefit balance in glycemic control toward a more beneficial outcome.
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Affiliation(s)
- R. David G. Leslie
- Centre for Diabetes and Metabolic Medicine, Institute of Cell and Molecular Science, St. Bartholomew's Hospital, London, United Kingdom
| | - Robert M. Cohen
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Cincinnati, Cincinnati, Ohio
- Medical Service, Cincinnati Veterans Affairs Medical Center, Cincinnati, Ohio
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90
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Abstract
Hemoglobin HbA(1c) (A(1c)) has been used clinically since the 1980s as a test of glycemic control in individuals with diabetes. The Diabetes Control and Complications Trial (DCCT) demonstrated that tight glycemic control, quantified by lower blood glucose and A(1c) levels, reduced the risk of the development of complications from diabetes. Subsequently, standardization of A(1c) measurement was introduced in different countries to ensure accuracy in A(1c) results. Recently, the International Federation of Clinical Chemists (IFCC) introduced a more precise measurement of A(1c) , which has gained international acceptance. However, if the IFCC A(1c) result is expressed as a percentage, it is lower than the current DCCT-aligned A(1c) result, which may lead to confusion and deterioration in diabetic control. Alternative methods of reporting have been proposed, including A(1c) -derived average glucose (ADAG), which derives an average glucose from the A(1c) result. Herein, we review A(1c) , the components involved in A(1c) formation, and the interindividual and assay variations that can lead to differences in A(1c) results, despite comparable glycemic control. We discuss the proposed introduction of ADAG as a surrogate for A(1c) reporting, review imprecisions that may result, and suggest alternative clinical approaches.
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Affiliation(s)
- Emily Jane Gallagher
- Division of Endocrinology, Diabetes and Bone Disease, Mount Sinai School of Medicine, New York City, New York 10029, USA.
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91
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Current literature in diabetes. Diabetes Metab Res Rev 2009; 25:i-x. [PMID: 19219862 DOI: 10.1002/dmrr.918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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92
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Red cell life span heterogeneity in hematologically normal people is sufficient to alter HbA1c. Blood 2008; 112:4284-91. [PMID: 18694998 DOI: 10.1182/blood-2008-04-154112] [Citation(s) in RCA: 312] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although red blood cell (RBC) life span is a known determinant of percentage hemoglobin A1c (HbA1c), its variation has been considered insufficient to affect clinical decisions in hematologically normal persons. However, an unexplained discordance between HbA1c and other measures of glycemic control can be observed that could be, in part, the result of differences in RBC life span. To explore the hypothesis that variation in RBC life span could alter measured HbA1c sufficiently to explain some of this discordance, we determined RBC life span using a biotin label in 6 people with diabetes and 6 nondiabetic controls. Mean RBC age was calculated from the RBC survival curve for all circulating RBCs and for labeled RBCs at multiple time points as they aged. In addition, HbA1c in magnetically isolated labeled RBCs and in isolated transferrin receptor-positivereticulocytes was used to determine the in vivo synthetic rate of HbA1c. The mean age of circulating RBCs ranged from 39 to 56 days in diabetic subjects and 38 to 60 days in nondiabetic controls. HbA1c synthesis was linear and correlated with mean whole blood HbA1c (R(2) = 0.91). The observed variation in RBC survival was large enough to cause clinically important differences in HbA1c for a given mean blood glucose.
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