Association of erythrocyte indices with glycated haemoglobin in pre-menopausal women

The potential impact and diagnostic value of inflammatory markers on diabetic foot progression in type II diabetes mellitus: A case-control study

BACKGROUND

The wound-healing process in diabetic foot is affected by pro and anti-inflammatory markers, and any disruption in the inflammatory reaction interferes with tissue homeostasis, leading to chronic non-wound healing.

AIM

This study aimed to determine the diagnostic value and effect of CRP, IL-6, TNF, and HbA1c on initiation the and progression of diabetic foot ulcers.

METHOD

ELISA was used to quantify IL-6, TNF, CRP, and HbA1c in 205 patients with diabetes, and 105 were diabetic foot free. The prevalence and progression of diabetic foot were also evaluated. The area under the curve (AUC) was calculated using the receiver operating characteristic (ROC) curve to analyze the predictive values. Forward stepwise logistic regression analysis was used to compute the odds ratio (OR) and the corresponding 95% confidence intervals (CIs).

RESULTS

CRP, IL-6, and FBS were found to be significant predictors of diabetic foot (OR=1.717, 95% CI=1.250-2.358, P=0.001; OR=1.434, 95% CI=1.142-1.802, P=0.002; and OR=1.040, 95% CI=1.002-1.080, P=0.037), respectively. The AUCs for CRP, IL-6, and HbA1c in predicting diabetic foot were 0.839, 0.728, and 0.834, respectively, demonstrating a good predictive value for each diagnostic marker.

CONCLUSION

The current study demonstrated that IL-6, CRP, and HbA1c may be useful biomarkers to indicate diabetic foot progression. Furthermore, our findings showed a substantial relationship between CRP and HbA1c in individuals with diabetic foot conditions.

Age and Red Blood Cell Parameters Mainly Explain the Differences Between HbA1c and Glycemic Management Indicator Among Patients With Type 1 Diabetes Using Intermittent Continuous Glucose Monitoring

BACKGROUND

Glycated hemoglobin (HbA1c) is the gold standard to assess glycemic control in patients with diabetes. Glucose management indicator (GMI), a metric generated by continuous glucose monitoring (CGM), has been proposed as an alternative to HbA1c, but the two values may differ, complicating clinical decision-making. This study aimed to identify the factors that may explain the discrepancy between them.

METHODS

Subjects were patients with type 1 diabetes, with one or more HbA1c measurements after starting the use of the Freestyle Libre 2 intermittent CGM, who shared their data with the center on the Libreview platform. The 14-day glucometric reports were retrieved, with the end date coinciding with the date of each HbA1c measurement, and those with sensor use ≥70% were selected. Clinical data prior to the start of CGM use, glucometric data from each report, and other simultaneous laboratory measurements with HbA1c were collected.

RESULTS

A total of 646 HbA1c values and their corresponding glucometric reports were obtained from 339 patients. The absolute difference between HbA1c and GMI was <0.3% in only 38.7% of cases. Univariate analysis showed that the HbA1c-GMI value was associated with age, diabetes duration, estimated glomerular filtration rate, mean corpuscular volume (MCV), red cell distribution width (RDW), and time with glucose between 180 and 250 mg/dL. In a multilevel model, only age and RDW, positively, and MCV, negatively, were correlated to HbA1c-GMI.

CONCLUSION

The difference between HbA1c and GMI is clinically relevant in a high percentage of cases. Age and easily accessible hematological parameters (MCV and RDW) can help to interpret these differences.

Effect of anemia and erythrocyte indices on hemoglobin A1c levels among pregnant women

BACKGROUND

Anemia is a common disorder among pregnant women; however, the effect of anemia on hemoglobin A1c (HbA1c) levels has not been adequately explored. We aim to examine the influence of anemia on the HbA1c concentration and investigate the relationship between erythrocyte indices and HbA1c levels during pregnancy.

METHODS

We performed a retrospective analysis of 1369 pregnant Chinese women. The clinical and analytical data were collected. Independent t-test and Analysis of Variance were used for comparative studies, and multiple linear regression analysis was used to identify the association between erythrocyte indices and HbA1c.

RESULTS

The differences in HbA1c between non-anemia and mild anemia were negligible, and the differences in HbA1c between non-anemia and moderate anemia were well within the allowable variability for clinical practice (≥0.5% absolute changes). Mean corpuscular hemoglobin (MCH) correlated with HbA1c significantly, independent of pregnancy, trimester, and anemia. The distinction of HbA1c levels between grades of Hb became no significant (P = 0.955), while differences between trimesters persisted after adjusting for MCH.

CONCLUSION

Mild and moderate anemia should not be the primary concern when using HbA1c to monitor blood glucose in pregnancy. MCH showed negative correlations with HbA1c independently, suggesting a previously unknown mechanism affecting HbA1c levels.

Complete blood counts with red blood cell determinants associate with reduced beta-cell function in seroconverted Swedish TEDDY children

OBJECTIVES

To investigate whether changes in complete blood count (CBC) in islet autoantibody positive children with increased genetic risk for type 1 diabetes are associated with oral glucose tolerance tests (OGTT) and HbA1c over time.

METHODS

The Environmental Determinants of Diabetes in the Young (TEDDY) study follows children with increased risk for type 1 diabetes in the United States, Germany, Sweden and Finland. In the current study, 89 Swedish TEDDY children (median age 8.8 years) positive for one or multiple islet autoantibodies were followed up to 5 (median 2.3) years for CBC, OGTT and HbA1c. A statistical mixed effect model was used to investigate the association between CBC and OGTT or HbA1c.

RESULTS

HbA1c over time increased by the number of autoantibodies (p < .001). Reduction in mean corpuscular haemoglobin (MCH) and mean cell volume (MCV) was both associated with an increase in HbA1c (p < .001). A reduction in red blood cell (RBC) counts (p = .003), haemoglobin (p = .002) and haematocrit (p = .006) levels was associated with increased fasting glucose. Increased red blood cells, haemoglobin, haematocrit and MCH but decreased levels of red blood cell distribution widths (RDW) were all associated with increased fasting insulin.

CONCLUSIONS

The decrease in RBC indices with increasing HbA1c and the decrease in RBC and its parameters with increasing fasting glucose in seroconverted children may reflect an insidious deterioration in glucose metabolism associated with islet beta-cell autoimmunity.

Association of time in range with hemoglobin A1c, glycated albumin and 1,5-anhydro-d-glucitol

AIMS/INTRODUCTION

Hemoglobin A1c (HbA1c), glycated albumin (GA) and 1,5-anhydro-d-glucitol (1,5-AG) are used as indicators of glycemic control, whereas continuous glucose monitoring (CGM) is used to assess daily glucose profiles. The aim of this study was to investigate the relationships between CGM metrics, such as time in range (TIR), and glycemic control indicators.

MATERIALS AND METHODS

We carried out retrospective CGM and blood tests on 189 outpatients with impaired glucose tolerance (n = 22), type 1 diabetes mellitus (n = 67) or type 2 diabetes mellitus (n = 100).

RESULTS

In type 1 diabetes mellitus and type 2 diabetes mellitus patients, HbA1c and GA were negatively correlated with TIR, whereas 1,5-AG was positively correlated with TIR. In type 1 diabetes mellitus patients, a TIR of 70% corresponded to HbA1c, GA and 1,5-AG of 6.9% (95% confidence interval [CI] 6.5-7.2%), 20.3% (95% CI 19.0-21.7%) and 6.0 µg/mL (95% CI 5.1-6.9 µg/mL), respectively. In type 2 diabetes mellitus patients, a TIR of 70% corresponded to HbA1c, GA and 1,5-AG of 7.1% (95% CI 7.0-7.3%), 19.3% (95% CI 18.7-19.9%) and 10.0 µg/mL (95% CI 9.0-11.0 µg/mL), respectively. TIR values corresponding to HbA1c levels of 7.0% were 56.1% (95% CI 52.3-59.8%) and 74.2% (95% CI 71.3-77.2%) in type 1 diabetes mellitus and type 2 diabetes mellitus patients, respectively.

CONCLUSIONS

The results of this study showed that the estimated HbA1c corresponding to a TIR of 70% was approximately 7.0% for both type 1 diabetes mellitus and type 2 diabetes mellitus patients, and that the estimated 1,5-AG calculated from the TIR of 70% might be different between type 1 diabetes mellitus and type 2 diabetes mellitus patients.

Effect of anaemia and erythrocyte indices on canine glycated haemoglobin

BACKGROUND

The major fraction of glycated haemoglobin (HbA1c) depends on blood glucose concentration and erythrocyte lifespan, and consequently erythrocyte indices may affect HbA1c; our objective was to study this effect in dogs.

METHODS

Blood samples from two (healthy and anaemic) age- and sex-matched, normoglycaemic populations were prospectively included. Advia 120 and Capillarys 2 flex-piercing were used for the haematological and HbA1c analyses, respectively.

RESULTS

Lower mean HbA1c was found in dogs with regenerative (n = 8, 0.88 ± 0.58%) and non-regenerative anaemia (n = 12, 1.36 ± 0.56%) compared to healthy ones (n = 40, 1.68 ± 0.48%); the difference was significant (p < 0.001) between the healthy dogs and those with regenerative anaemia. HbA1c was significantly correlated (p < 0.05) with red blood cell count (r = 0.506), haemoglobin (r = 0.474), haematocrit (r = 0.467), mean corpuscular volume (r = -0.289), mean corpuscular haemoglobin concentration (r = 0.284), red cell distribution width (r = -0.286) and reticulocytes (r_s = -0.542).

CONCLUSION

Anaemia, particularly if regenerative, can lower HbA1c. The significant correlation between HbA1c and erythrocyte indices likely reflects the effect of erythrocyte turnover on HbA1c.

Association of hemoglobin H (HbH) disease with hemoglobin A1c and glycated albumin in diabetic and non-diabetic patients

OBJECTIVES

Hemoglobin A_1c (HbA_1c) and glycated albumin (GA) are glycemic control status indicators in patients with diabetes mellitus. Hemoglobin H (HbH) disease is a moderately severe form of α-thalassemia. Here we examine the usefulness of HbA_1c and GA in monitoring glycemic control in patients with HbH disease.

METHODS

HbA_1c, GA, and an oral glucose tolerance test were performed in 85 patients with HbH disease and 130 healthy adults. HbA_1c was measured using five methods, including two systems based on cation-exchange high-performance liquid chromatography (Variant II Turbo 2.0 and Bio-Rad D100), a capillary zone electrophoresis method (Capillarys 3 TERA), a boronate affinity HPLC method (Premier Hb9210), and an immunoassay (Cobas c501).

RESULTS

Significant lower levels of HbA_1c were observed in patients with HbH disease than in healthy adults. In contrast, GA showed no statistically significant differences between participants with and without HbH disease. A considerable number of diabetic patients with HbH disease would be missed if using HbA_1c as a diagnostic criterion for diabetes mellitus.

CONCLUSIONS

GA but not HbA_1c is suitable for monitoring glycemic control in patients with HbH disease that can modify the discriminative ability of HbA_1c for diagnosing diabetes.

Assessment of hematologic indices and their correlation to hemoglobin A1c among Bosnian children with type 1 diabetes mellitus and their healthy peers

Background

Altered levels of many hematological parameters have been directly associated with diabetes in adults, while studies on children with type 1 diabetes mellitus are lacking. The aim of this study was to determine hematological indices in diabetic Bosnian children in comparison to healthy controls as well as to correlate their levels to blood glucose and hemoglobin A1c.

Methods

100 healthy and 100 children with type 1 diabetes mellitus (age 1-18) were included in this study. Complete blood count, hemoglobin A1c, and glucose were tested. Results were analysed by IBM SPSS Statistics version 23.

Results

Significant differences (p<0.05) between healthy and diabetic children were found in relation to HbA1c, glucose, mean platelet volume, the number of white blood cells and erythrocytes, hematocrit, hemoglobin and MCH values. No gender differences or significant age differences were seen for hemoglobin, hematocrit, and MCV, while platelets, MPV, and MCH differed by age only in healthy children. When diabetic children were classified according to HbA1c levels, significant differences were seen for erythrocyte count and hematocrit value (p=0.013 and 0.019, respectively). The number of erythrocytes and white blood cells correlated significantly with HbA1c (p=0.037 and 0.027, respectively).

Conclusions

Lower levels of erythrocytes, hematocrit, and hemoglobin in diabetic compared to healthy children indicate possible development of anemia, while higher MCV, MCH, and MPV values indicate an alteration in erythrocyte morphology. Hematological indices could be a useful inexpensive tool in the diagnosis and follow up of type 1 diabetes in children.

Reference Interval of Hemoglobin A1c and Influence of Hematological Parameters on Its Serum Concentration in Dogs

HbA1c could be an alternative to fructosamine as a marker for glucose levels over a longer period. In this study, we calculated a reference interval for HbA1c in dogs and investigated the correlation of HbA1c with hemoglobin and different hematological parameters. In total, 110 blood samples from dogs were investigated. Significant negative correlations were found between HbA1c and erythrocyte count, hemoglobin concentration, as well as hematocrit. There was a tendency in the red cell distribution width. No significant correlation was found in the reticulocyte number and the erythrocyte indices. In conclusion, there is an association of different blood parameters with the HbA1c concentration, which have to be considered for the interpretation of HbA1c.

A multicenter all-inclusive prospective study on the relationship between glycemic control markers and maternal and neonatal outcomes in pregnant women

OBJECTIVE

Pregnant women afflicted with gestational diabetes mellitus (GDM) and diabetes mellitus (DM) are prone to both maternal and neonatal complications. Due to this, it is of importance to sustain a strict glycemic control during this time. Unfortunately, there is a lack of evidence-based medical research for the control criteria during pregnancy. Therefore, to develop better method of glycemic control for pregnant women, we conducted a multicenter all-inclusive prospective study to investigate the association between glycemic control markers and maternal and neonatal outcomes.Research design and methods: Four hundred fifty-two women were included in the study. Fasting blood glucose (FBG), HbA1c and glycated albumin (GA), and ferritin levels were measured at different gestational periods and compared to the pregnancy outcomes.

RESULTS

The reference interval of GA and HbA1c was determined in Trimester I, II, III: 11.0-16.3%, 10.1-15.2%, and 9.5-14.6%, and 4.8-5.7%, 4.4-5.4%, and 4.7-5.8%, respectively. It was found that at the later stages of pregnancy, there was a reduction in ferritin levels and increase in HbA1c levels. Only in the GDM group, it was noticed that the frequency of total neonatal and maternal complications were significantly higher on comparison with the normal group (30.1 vs. 18.4%, p = .017 and 21.0% vs. 12.0%, p = .031, respectively). For the frequency of cesarean section and macrosomia in GDM group, GA > 15.69% group was significant higher compared to those of GA ≤ 15.69% group (p = .021 and p = .001, respectively). For HbA1c, no significant differences were observed.

CONCLUSIONS

A reference interval of HbA1c and GA was developed for Chinese pregnant women. We found that the GDM group had a higher frequency of neonatal and maternal complications. As only GA levels and not HbA1c, were associated with cesarean section and macrosomia in GDM, we hypothesize that GA could be an appropriate glycemic control marker for pregnant mothers.

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

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

Correlation of Hemoglobin A1c with Red Cell Width Distribution and Other Parameters of Red Blood Cells in Type II Diabetes Mellitus

Objective

To determine the correlation of glycated hemoglobin (HbA1c) with red cell width (RDW) and other analytic parameters of red blood cells (RBCs) in type II diabetic patients.

Design

Cross-sectional analytical study.

Place and duration of the study

Al-Tibri Medical College and Hospital Karachi; from July 2017 to January 2018.

Patients and methods

This cross-sectional study was conducted on diagnosed type II diabetic patients visiting the outpatient department of medicine at Al-Tibri Medical College Hospital from July 2017 to January 2018. Diabetes mellitus was diagnosed according to American Diabetes Association (ADA) guidelines. After taking consent and conducting a clinical assessment (include history and physical examination), laboratory tests, such as fasting blood glucose, random blood glucose, complete blood count (CBC), and HbA1c, were collected on proforma.

Results

A total of 119 patients were eligible for the study with a mean age of 48.63±12.462 (range 24-76) years; among those, males were 74 (62.2%) and females were 45 (37.8%). The mean duration of diabetes mellitus (DM) was 6.735±3.759 (range 1-20) years. The mean hemoglobin of patients was 11.59±1.315 gm/dl. The mean corpuscular volume (MCV) was 76.65±11.121 fl and the mean RDW was found to be 18.287±4.352, with the highest value of 30.20. The mean MCH was 30.223±23.873 pg, with the highest value of 38.4 pg. The mean cell hemoglobin concentration (MCHC) was 28.214±4.7498 mg/dl.

The HbA1c of the study population was found to be moderately uncontrolled and the mean HbA1c was 8.278±5.015%, with the highest value of 16.2%. The mean fasting blood sugar was 158±39.50 mg/dl while the mean random blood sugar was 236±57.390 mg/dl.

The correlation of HbA1c with RDW turned out to be significant statistically (p-0.035) while other RBCs and/or hematological parameters, such as MCV, hemoglobin, and platelets, revealed no significant correlation.

Conclusion

The study highlighted that RDW has a significant correlation with HbA1c and is an inexpensive and freely available test so it may be used as a marker of glycemic status.

The ratio of fasting plasma glucose to hemoglobin A1c as a predictor of all-cause mortality in individuals with normal glucose levels: The Jichi Medical School cohort study

Objectives:

The fasting plasma glucose/hemoglobin A1c ratio is considered a marker associated with glucose metabolism disorders, including fasting hyperglycemia. However, it remains unclear whether this ratio can be used for the prevention of deaths in individuals with normal fasting plasma glucose levels. This study aimed to see the predictive value of the fasting plasma glucose/hemoglobin A1c ratio for all-cause mortality in a general population with normal fasting plasma glucose levels.

Methods:

The study investigated prospectively a cohort of 1087 multi-regional, community-dwelling Japanese participants (women, 69.2%) for a follow-up period of 11.3 years. We included individuals with fasting plasma glucose levels <6.11 mmol/L and excluded those meeting the diabetes criteria. All-cause mortality was the primary outcome and hazard ratios were calculated using the Cox proportional hazard model after dividing the fasting plasma glucose/hemoglobin A1c ratios into tertiles.

Results:

There were 54 deaths (25 women) during the follow-up period. The high tertile group had a significantly higher hazard ratio for all-cause mortality than the low tertile group in women (multivariate-adjusted hazard ratio = 4.45; 95% confidence interval = 1.26–15.72), but not clearly in men.

Conclusion:

The data of the population-based cohort study suggest that a high fasting plasma glucose/hemoglobin A1c ratio can predict all-cause mortality in women with normal fasting plasma glucose levels.

Impact of Anemia and Red Cell Indices on the Diagnosis of Pre-Diabetes and Diabetes in Indian Adult Population: Is there a Cut-off Guide for Clinicians?

BACKGROUND

It is well known that anemia and red cell turn over affects the HbA1c value. Iron deficiency anemia increases the HbA1c and haemolytic anemia lowers it. However, the cut-off of haemoglobin (Hb) or red-cell indices when the HbA1c value becomes unreliable is not known.

AIM

We sought to find out values of HbA1c and red-cell indices where there is considerable discordance between HbA1c and plasma glucose (PG) values in the diagnosis of diabetes (DM) and pre-diabetes (Pre-DM) making HbA1c values unreliable.

METHODS

A cross-sectional study of 237 non-diabetic subjects who attended our out-patient division of preventive health check-up clinics, between November 2016 and December 2017. Data was collected only from relatively healthy subjects who had voluntarily opted for undergoing a preventative health check-up (including a diabetes screening). Patients were classified as concordant (fasting and 2-hr post meal glucose values are in agreement with HbA1c) and discordant (values are not in agreement with HbA1c).

RESULTS

A total of 237 patients (73% males) with mean age was 47.2±9.7 years (range 25-75) were included in the study. The HbA1c definition group had more diagnosis of DM (153 vs 96) and but lesser numbers of pre-DM (66 vs 102) compared to the PG group. Out of 237 patients, 133 (56%) showed concordance and 104 (44%) were discordant. The FPG, 2h-PPBG and HbA1c are significantly higher in the concordant group. The Hb value and MCV were significantly higher (p<0.05) in concordant group whereas, RDW and platelets are significantly higher (p<0.05) in discordant group. The highest rate of discordance was noted in the HbA1c strata of 6.5-7% (72%) followed by HbA1c of 5-6.4% (42%) and least in the HbA1c strata >7% (20%). While no single Hb or MCV value could predict discordance, a RDW value >17 was consistently associated with discordance across all the HbA1c strata.

CONCLUSION

A HbA1c below 7% is significantly influenced by red-cell turn over indices and clinicians need to perform additional testing using plasma glucose levels to confirm the presence of diabetes or pre-diabetes. In patients whose RDW >17, HbA1c should be replaced by 75gm OGTT as a test of choice for diagnosis of diabetes or pre-diabetes.

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.

Beyond self-monitored plasma glucose and HbA1c: the role of non-traditional glycaemic markers in gestational diabetes mellitus

Strict glycaemic management is the cornerstone of metabolic control in gestational diabetes mellitus (GDM). Current monitoring standards involve self-monitoring plasma glucose (SMBG) and haemoglobin A1c (HbA1c). However, both have important limitations. SMBG only reflects instantaneous blood glucose and the inconvenience of self-collecting blood frequently results in poor compliance. HbA1c provides information on blood glucose levels from the previous 2 to 3 months and it is influenced by iron-deficient states, common during pregnancy. There is an urgent need for new shorter-term glycaemic markers, as glycated albumin, fructosamine or 1,5-anhydroglucitol. Glycated albumin seems especially interesting as it provides information on blood glucose levels over the foregoing 2-3 weeks and it is not influenced by iron deficiency or the dilutional anaemia of pregnancy. Fructosamine has a precise and inexpensive measurement and it is not affected by haemoglobin characteristics. This review further discusses the potential value of these non-traditional indicators of glycaemic control in patients with GDM, outlining their possible future applications.

Influence of Iron Deficiency on HbA1c Levels in Pregnant Women: Comparison with Non-Pregnant Women

Although HbA1c is widely used as a glycemic control indicator, HbA1c is known to show falsely high levels in patients in an iron deficient state (IDS). We compared the influence of IDS on HbA1c levels between pregnant women, due to mainly an increase in demand for iron without bleeding, and non-pregnant women, due to mainly bleeding (menstruation). We studied 42 non-diabetic pregnant women (pregnant group) and 42 age-matched non-pregnant women with normal glucose tolerance (non-pregnant group). We compared HbA1c and glycated albumin (GA) levels between IDS and normal iron state (NIS) in both groups. Furthermore, we analyzed the correlation between indicators of glycemic control and iron-related parameters [mean corpuscular hemoglobin, serum transferrin saturation (%Tf), and serum ferritin] in both groups. Compared with non-pregnant women, pregnant women had significantly lower %Tf and serum ferritin levels and significantly higher morbidity of IDS. HbA1c, but not GA, had significantly higher levels in pregnant women with IDS compared with NIS; however, HbA1c in non-pregnant women showed no significant difference for both IDS and NIS. In pregnant women, significant negative correlations were observed between HbA1c and iron-related parameters. In non-pregnant women, negative correlations were observed between HbA1c and these parameters, but they were not significant. No significant correlations were observed between GA and iron-related parameters in both groups. HbA1c levels in pregnant women were found to be largely affected by iron deficiency compared with non-pregnant women. For this reason, GA, which is not affected by iron deficiency, is desirable for use in the assessment of glycemic control during pregnancy.

Effect of iron supplementation on HbA1c levels in pregnant women with and without anaemia

BACKGROUND

Iron deficiency anaemia has been associated with higher HbA1c levels. However, during and after iron supplementation there is a decrease in HbA1c results, causing a misinterpretation. Our aim was to analyse the effect of iron supplementation on HbA1c levels in nondiabetic pregnant women with and without anaemia.

METHODS

Pregnant women in prenatal care, without gestational diabetes (GDM) or previous diabetes mellitus (DM) that performed an oral glucose tolerance test (OGTT) in the third trimester of pregnancy were invited to participate. Clinical and laboratorial analyses were performed, including standardized questionnaire, OGTT, full blood count and HbA1c.

RESULTS

A total of 231 pregnant women without DM or GDM were included in the study. According to anaemia and/or iron supplementation, we divided women in: no iron and no anaemia - Group 1 (N=86); no iron and with anaemia - Group 2 (N=29); iron and no anaemia - Group 3 (N=87); iron and anaemia - Group 4 (N=29). There was statistically a significant, although no clinically relevant, difference between HbA1c values in pregnant women in Groups 1 and 4 [5.1±0.4% (32±4.4mmol/mol) and 4.8±0.3% (29±3.3mmol/mol), P<0.01; respectively]. HbA1c values in pregnant women in Groups 1, 2 and 3 were similar, independently of anaemia [5.1±0.4% (32±4.4mmol/mol); 5.0±0.4% (31±4.4mmol/mol) and 5.0±0.4% (31±4.4mmol/mol); p>0.05; respectively].

CONCLUSIONS

Iron supplementation during pregnancy does not affect HbA1c levels and has no clinical impact in the final interpretation of results in the absence of anaemia or presence of mild anaemia. Interpreting HbA1c results in pregnant women during iron therapy and with moderate or severe anaemia still requires caution.

Iron deficiency anemia and glucose metabolism

Iron deficiency anemia (IDA) is a global public health problem affecting both developing and developed countries with major consequences for human health as well as social and economic development. It occurs at all stages of the life cycle, but is more prevalent in pregnant women and young children. IDA appears to be more common in diabetic patients compared to non-diabetic population. Iron deficiency (ID) and IDA can impair glucose homeostasis in animals and human and may negatively affect glycemic control and predispose to more complications in diabetic patients. On the other hand diabetes and its complications are associated with anemia and its correction improves diabetes control and may prevent or delay the occurrence of complications. Physicians treating this form of anemia should be aware of its negative effect on glycemic control in normal and diabetic patients (both type 1 and type 2). They should prevent ID and treat early all those with IDA.This brief review aims to enlighten the different effects of IDA on glucose metabolism in normal and diabetic patients.

Study of Glycated Haemoglobin (HbA1c) In Non-Diabetic Subjects with Subclinical Hypothyroidism

INTRODUCTION

India has the higher prevalence of prediabetes, diabetes and hypothyroidism. Subclinical Hypothyroidism (SH) is more prevalent in the females than in the males. Studies have shown the elevated HbA1c in the non-diabetic hypothyroid patients. SH is defined by normal serum triiodothyronine (T₃), thyroxine (T₄) levels and serum Thyroid Stimulating Hormone (TSH) level falling between 4.2 to 10 mU/L.

AIM

To study the HbA1c level in the non-diabetic SH patients and to compare the HbA1c level with the controls.

MATERIALS AND METHODS

This case-control study was conducted on 200 subjects. A total of 100 subjects of the SH without diabetes were selected on the basis of the serum TSH (> 4.2 to < 10 mU/L), Fasting Blood Sugar (FBS) (< 110 mg/dl) level and another 100 age and sex matched normal healthy individuals were selected as the control. The HbA1c levels were measured using Immunoturbidimetry method in the Cobas Integra 400 plus. An independent t-test is applied to find out the statistically significant difference in the level of HbA1c in the case and the control groups.

RESULTS

Subjects with the non-diabetic SH had a significant higher level (5.70±0.35 %) of the HbA1c than the controls (5.26±0.17 %) (p<0.0001). There was no significant difference between the cases and the controls for the age, sex, FBS, vitamin D₃, Haemoglobin (Hb), serum T₃ and serum T₄ levels.

CONCLUSION

Our data suggest that the non-diabetic subjects with SH show misleadingly high levels of the HbA1c. Therefore, the effect of altered levels of the serum TSH on the HbA1c must be considered when interpreting the HbA1c for the diagnosis of diabetes in the SH patients.

Impact of Mean Cell Hemoglobin on Hb A1c-Defined Glycemia Status

BACKGROUND

Several hematological alterations are associated with altered hemoglobin A_1c (Hb A_1c). However, there have been no reports of their influence on the rates of exceeding standard Hb A_1c thresholds by patients for whom Hb A_1c determination is requested in clinical practice.

METHODS

The initial data set included the first profiles (complete blood counts, Hb A_1c, fasting glucose, and renal and hepatic parameters) of all adult patients for whom such a profile was requested between 2008 and 2013 inclusive. After appropriate exclusions, 21844 patients remained in the study. Linear and logistic regression models were adjusted for demographic, hematological, and biochemical variables excluded from the predictors.

RESULTS

Mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) correlated negatively with Hb A_1c. Fasting glucose, MCH, and age emerged as predictors of Hb A_1c in a stepwise regression that discarded sex, hemoglobin, MCV, mean corpuscular hemoglobin concentration (MCHC), serum creatinine, and liver disease. Mean Hb A_1c in MCH interdecile intervals fell from 6.8% (51 mmol/mol) in the lowest (≤27.5 pg) to 6.0% (43 mmol/mol) in the highest (>32.5 pg), with similar results for MCV. After adjustment for fasting glucose and other correlates of Hb A_1c, a 1 pg increase in MCH reduced the odds of Hb A_1c-defined dysglycemia, diabetes and poor glycemia control by 10%-14%.

CONCLUSIONS

For at least 25% of patients, low or high MCH or MCV levels are associated with increased risk of an erroneous Hb A_1c-based identification of glycemia status. Although causality has not been demonstrated, these parameters should be taken into account in interpreting Hb A_1c levels in clinical practice.

Effect of iron deficiency anaemia on HbA1c levels is dependent on the degree of anaemia

OBJECTIVES

Studies suggest that iron deficiency anaemia (IDA) is associated with higher HbA1c levels. We conducted a control–case study to investigate the effect of IDA on HbA1c levels, measured by two commonly used methods, in non-diabetic individuals.

DESIGN AND METHODS

A total of 122 patients were included, 61 patients with IDA and 61 patients without anaemia. HbA1c was measured by both ion exchange HPLC Variant II Turbo BioRad and immunoturbidimetry (IT) Tina Quant II Roche Diagnostics in each sample. HbA1c results were compared between groups. For correlation analysis, patients were considered altogether.

RESULTS

There was a significant difference between the results of HbA1c in patients with IDA [HPLC 5.6 ± 0.4% (38 ± 4.4 mmol/mol) and IT 5.7 ± 0.4% (39 ± 4.4 mmol/mol)] and those measured in patients without anaemia [HPLC 5.3 ± 0.4% (34 ± 4.4 mmol/mol) and IT 5.3 ± 0.3% (34 ± 3.3 mmol/mol)], (p < 0.001). Significant negative correlations were observed between total haemoglobin (Hb), haematocrit, mean corpuscular volume (MCV) and ferritin with HbA1c values measured by IT (r = − 0.557; r = − 0.539; r = − 0.488; r = − 0.499; p < 0.01; respectively). These negative correlations were weaker with HbA1c measured by HPLC (r = − 0.272; r = − 0.250; r = − 0.273; r = − 0.229 for Hb, haematocrit, MCV and ferritin; p < 0.05; respectively). HbA1c results were higher in patients with moderate and severe anaemia. However mild anaemia did not show significant effects on HbA1c results measured by both methods.

CONCLUSIONS

IDA affects HbA1c results and this effect is dependent on anaemia degree. These upward changes are statistically significant but they may be not clinically relevant when the overall variability of the HbA1c test is considered. The presence of slight anaemia is likely to have a minor effect on HbA1c levels favouring its use to diagnose diabetes in patients with mild anaemia.

Indicators of glycemic control in patients with gestational diabetes mellitus and pregnant women with diabetes mellitus

Recently, it has become clear that mild abnormal glucose tolerance increases the incidence of perinatal maternal-infant complications, and so the definition and diagnostic criteria of gestational diabetes mellitus (GDM) have been changed. Therefore, in patients with GDM and pregnant women with diabetes mellitus, even stricter glycemic control than before is required to reduce the incidence of perinatal maternal-infant complications. Strict glycemic control cannot be attained without an indicator of glycemic control; this review proposes a reliable indicator. The gold standard indicator of glycemic control in patients with diabetes mellitus is hemoglobin A1c (HbA1c); however, we have demonstrated that HbA1c does not reflect glycemic control accurately during pregnancy because of iron deficiency. It has also become clear that glycated albumin, another indicator of glycemic control, is not influenced by iron deficiency and therefore might be a better indicator of glycemic control in patients with GDM and pregnant women with diabetes mellitus. However, large-population epidemiological studies are necessary in order to confirm our proposal. Here, we outline the most recent findings about the indicators of glycemic control during pregnancy including fructosamine and 1,5-anhydroglucitol.

The effect of anaemia and abnormalities of erythrocyte indices on HbA1c analysis: a systematic review

AIMS/HYPOTHESIS

The use of HbA1c for the diagnosis of diabetes is now widely advocated despite caveats to its use. Anaemia is cited as a major confounder to this use; however, the effect of erythrocyte indices and to what degree anaemia influences HbA1c levels is not known.

METHODS

A systematic electronic database search of MEDLINE, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL) and the Cochrane Library was conducted for relevant articles published between January 1990 and May 2014. Included studies had at least one measurement of HbA1c and glucose, and a least one index of haematinic deficiency, involving non-pregnant adults, not known to have diabetes.

RESULTS

A total of 12 articles from 544 were included. The majority of studies focused on iron deficiency anaemia (IDA) and, in general, demonstrated that the presence of iron deficiency with or without anaemia led to an increase in HbA1c values compared with controls, with no concomitant rise in glucose indices. Data on the effects of other indices of erythrocyte abnormalities on HbA1c are limited but show a possible decrease in HbA1c values with non-iron deficiency forms of anaemia.

CONCLUSIONS/INTERPRETATION

HbA1c is likely to be affected by iron deficiency and IDA with a spurious increase in HbA1c values; conversely, non-IDA may lead to a decreased HbA1c value. This may lead to confusion when diagnosing diabetes using HbA1c. This review clearly identifies the need for more evidence, especially in identifying the types and degrees of anaemia likely to have significant impact on the reliability of HbA1c.

Implications of iron deficiency/anemia on the classification of diabetes using HbA1c

Background/Objectives:

Nonglycemic factors like iron deficiency (ID) or anemia may interfere with classification of diabetes and prediabetes using hemoglobin A1c (HbA1c). However, few population-based studies of diabetes in areas with endemic ID/anemia have been conducted. We aimed to determine how mutually exclusive categories of ID alone, anemia alone and iron-deficiency anemia (IDA) were each associated with prediabetes and diabetes prevalence using fasting blood glucose (FBG) versus HbA1c in a population-based study of adults with endemic ID/anemia.

Subjects/Methods:

We used data from the China Health and Nutrition Survey, a longitudinal, population-based study across 228 communities within nine provinces of China. This analysis included 7308 adults seen in the 2009 survey aged 18–75 years. We used descriptive and covariate-adjusted models to examine relative risk of prediabetes and diabetes using FBG alone, HbA1c alone, HbA1c and FBG, or neither (normoglycemia) by anemia alone, ID alone, IDA or normal iron/hemoglobin.

Results:

Approximately 65% of individuals with diabetes in our sample were concordantly classified with diabetes using both FBG and HbA1c, while 35% had a discordant diabetes classification: they were classified using either FBG or HbA1c, but not both. Fewer participants with ID alone versus normal iron/hemoglobin were classified with diabetes using HbA1c only. From covariate-adjusted, multinomial regression analyses, the adjusted prevalence of prediabetes using HbA1c only was 22% for men with anemia alone, but 13% for men with normal iron/hemoglobin. In contrast, the predicted prevalence of prediabetes using HbA1c only was 8% for women with ID alone, compared with 13% for women with normal iron/hemoglobin.

Conclusions:

These findings suggest potential misclassification of diabetes using HbA1c in areas of endemic ID/anemia. Estimating diabetes prevalence using HbA1c may result in under-diagnosis in women with ID and over-diagnosis in men with anemia.

Haemoglobin A1c in the diagnosis and monitoring of diabetes mellitus

Haemoglobin A(1c) (HbA(1c)) is due to celebrate its 40th birthday. Many people would argue that the clinical studies relating the test to diabetes complications while in its late 20s are likely to be its finest ever achievement. However, this article looks at how HbA(1c) has matured since then and discusses in detail how its many strengths and idiosyncrasies as a marker of glycaemic risk have, as a 30-something, become more clearly understood. As HbA(1c) approaches middle age, this paper also describes how the test appears to be developing a mid-life crisis, as debate over how its results should be expressed seems likely to divide opinion among clinicians for some time to come.

Factors affecting A1C in non-diabetic individuals: Review and meta-analysis

We carried out a systematic review and meta-analyses of studies that evaluated the possible effects of anemia, variant hemoglobin, and uremia on A1C levels in individuals without diabetes (DM). Medline and Embase were searched for studies that measured A1C values in groups with and without iron deficiency anemia (IDA) and/or iron deficiency (ID), variant hemoglobin and/or uremia by standardized methods. The difference between A1C levels in the groups with and without interferences was obtained by using random-effects meta-analysis and the effect size was presented as absolute difference of means (95% CI). Ten studies fulfilled the inclusion criteria, providing data from 11,176 participants without DM. There were no statistically significant differences in A1C in the presence of IDA/ID, HbS, and uremia by HPLC and uremia by immunoassay [0.79% (95% IC -0.39; 1.97), -0.13% (95% IC -0.51; 0.26), 0.15% (95% CI -0.58; 0.88) and -0.19% (95% CI -0.78; 0.40), respectively]. The effects of HbAS and uremia on A1C levels are within the expected individual variation and should not affect A1C results to diagnose DM. However, the effects of IDA/ID remain inconclusive and further studies are needed to clarify the glycation mechanisms in individuals with IDA/ID without diabetes.

Interpretation of HbA1c : association with mean cell volume and haemoglobin concentration

AIM

The utility of HbA1c in diabetes diagnosis is reduced in settings associated with altered haemoglobin glycation. We have studied whether HbA1c varies with mean cell volume and mean cell haemoglobin concentration as measures of haemoglobin metabolism.

METHODS

Randomly selected adults from rural Victoria, Australia, were invited for biomedical assessment. After excluding patients with known diabetes and/or serum creatinine ≥ 0.12 mmol/l, 1315 adults were included. Demography, arthropometric measurements, oral glucose tolerance test, analyses of full blood count and HbA1c were undertaken.

RESULTS

After adjusting for age, sex, ethnicity, BMI, town and socio-economic status, there were no significant differences in haemoglobin, mean cell volume or mean cell haemoglobin concentration by glycaemic status (defined by oral glucose tolerance test). HbA1c was significantly and independently associated with fasting glucose, town, mean cell haemoglobin concentration, ethnicity, age and BMI among men < 50 years (R² = 33.8%); fasting glucose, 2-h glucose, mean cell haemoglobin concentration and town among men ≥ 50 years (R² = 47.9%); fasting glucose, mean cell volume, mean cell haemoglobin concentration, town, 2-h glucose and age among women < 50 years (R² = 46.3%); fasting glucose, mean cell haemoglobin concentration, mean cell volume and 2-h glucose among women ≥ 50 years (R² = 51.6%). A generalized linear model showed a gradient from an adjusted mean HbA1c of 36 (95% CI 34-38) mmol/mol with a mean cell haemoglobin concentration of ≤ 320 g/l to 30 (95% CI 29-31) mmol/mol with a mean cell haemoglobin concentration of > 370 g/l. The gradient across mean cell volume was negative, but only by 1 mmol/mol (0.1%) HbA1c .

CONCLUSION

A mean HbA1c difference of 5 mmol/mol (0.5%) across the mean cell haemoglobin concentration reference range suggests that an accompanying full blood count examination may be required for its use in the diagnosis of diabetes. Further studies are required to confirm this.

1,5-Anhydroglucitol and glycated albumin in glycemia

The main purpose of treating diabetes is to prevent the onset and the progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring the plasma glucose level in diabetic patients as close as possible to that in healthy subjects and try to maintain good glycemic control over the long term. Glycated hemoglobin (HbA1c), glycated albumin (GA), fructosamine, and 1,5-anhydroglucitol (1,5 AG) are used for evaluating glycemic control. At present, HbA1c is widely used as a gold standard index for glycemic control in clinical practice. While HbA1c reflects the long-term glycemic control state (for the past 1-2 months), it does not accurately reflect glycemic control in the clinical state in which glycemic control improves or deteriorates in the short-term. It is also known that HbA1c in patients with hematological disorders such as anemia and variant hemoglobin shows an abnormal value. In addition, HbA1c mainly reflects the mean plasma glucose but does not reflect the postprandial plasma glucose. On the other hand, GA and 1,5-AG reflect intermediate- or short-term glycemic control and are not influenced by hemoglobin metabolism. While 1,5-AG is known to reflect the postprandial plasma glucose, it was shown recently that GA also reflects the postprandial plasma glucose. This chapter summarizes the measurement methods, usage methods, evidence, and problems concerning such indices for glycemic control.

Inaccuracy of haemoglobin A1c among HIV-infected men: effects of CD4 cell count, antiretroviral therapies and haematological parameters

BACKGROUND

There is limited evidence that among HIV-infected patients haemoglobin A1c (HbA1c) values may not accurately reflect glycaemia. We assessed HbA1c discordance (observed HbA1c - expected HbA1c) and associated factors among HIV-infected participants in the Multicenter AIDS Cohort Study (MACS).

METHODS

Fasting glucose (FG) and HbA1c were measured at each semi-annual MACS visit since 1999. All HIV-infected and HIV-uninfected men for whom at least one FG and HbA1c pair measurement was available were evaluated. Univariate median regression determined the association between HbA1c and FG by HIV serostatus. The relationship between HbA1c and FG in HIV-uninfected men was used to determine the expected HbA1c. Generalized estimating equations determined factors associated with the Hb1Ac discordance among HIV-infected men. Clinically significant discordance was defined as observed HbA1c - expected HbA1c ≤-0.5%.

RESULTS

Over 13 years, 1500 HIV-uninfected and 1357 HIV-infected men were included, with a median of 11 visits for each participant. At an FG of 125 mg/dL, the median HbA1c among HIV-infected men was 0.21% lower than among HIV-uninfected men and the magnitude of this effect increased with FG >126 mg/dL. Sixty-three percent of HIV-infected men had at least one visit with clinically significant HbA1c discordance, which was independently associated with: low CD4 cell count (<500 cells/mm(3)); a regimen containing a protease inhibitor, a non-nucleoside reverse transcriptase inhibitor or zidovudine; high mean corpuscular volume; and abnormal corpuscular haemoglobin.

CONCLUSION

HbA1c underestimates glycaemia in HIV-infected patients and its use in patients with risk factors for HbA1c discordance may lead to under-diagnosis and to under-treatment of established diabetes mellitus.

Glycated albumin; clinical usefulness

The main purpose of treating diabetes is to prevent the onset and progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring plasma glucose levels as close as possible to those in healthy subjects and maintain good glycemic control over the long term. Since glycation among various proteins is increased in diabetic patients compared with non-diabetic subjects, glycated protein can be used as a glycemic control indicator. Currently, among these glycated proteins, HbA1c is used as the gold standard of glycemic control indicators. However, HbA1c does not accurately reflect the actual status of glycemic control in some conditions with rapid changes in glycemic control and in patients with anemia (hemolytic anemia, iron deficiency anemia, etc.) and variant hemoglobin. In comparison, glycated albumin (GA) more accurately reflects changes in plasma glucose during the short term and postprandial plasma glucose. GA also reflects glycemic control in patients with hematologic disorders whereas GA does not reflect glycemic control in patients with disorder of albumin metabolism. GA is a glycemic control indicator which overcomes most of the disadvantages of HbA1c, and could be therefore expected to replace HbA1c as the standard glycemic control indicator in the near future. However, it is necessary to accumulate more evidences from large research studies on the effective directions for measuring GA.

Elevation of HbA1C in Non-diabetic Hypothyroid Individuals: Is Anaemia the Connecting Link? -A Preliminary Study

AIM

Studies have shown elevated HbA1C in non-diabetic hypothyroid patients. Hypothyroid patients often show anaemia as an associated feature which is an another condition showing falsely elevated A1C. Hence this study is aimed to investigate whether elevated A1C in hypothyroidism can be attributed to anaemia.

MATERIAL AND METHODS

HbA1C levels of 120 non-diabetic hypothyroid patients (30 microcytic hypochromic anaemia, 30 normocytic normochromic anaemia and 60 non anemic patients) with 120 age, sex, plasma glucose levels and anaemia status matched controls were assessed. Anaemia status was determined by ferritin, Haemoglobin, red cell indices and peripheral smear. Glycemic status was determined by fasting Plasma glucose.

RESULTS

HbA1C levels in hypothyroid patients with hypochromic microcytic anaemia and normocytic normochromic anaemia were 6.82 ± 0.71% & 6.32 ± 0.75% against 6.43 ± 0.43% & 5.87 ± 0.46 % of euthyroid anaemia matched controls respectively. While hypothyroid non anemic patients showed A1C levels of 5.91 ± 0.31% against 5.46 ± 0.62% of euthyroid non anemic controls. Hypothyroid Patients with anaemia had a significant odds ratio 3.16 (95% CI 1.426-7.016) for HbA1C > 6.5.

DISCUSSION AND CONCLUSION

Non-diabetic hypothyroid individuals with anaemia shows elevate A1C levels in prediabetes range. Hence care should be excercised while using HbA1C as a diagnostic tool for diabetes in such patients.

Manjrekar P, P. Babu R, Hegde A, M.S. R. Influence of iron deficiency anemia on hemoglobin A1c levels in diabetic individuals with controlled plasma glucose levels

INTRODUCTION

Hemoglobin A1C (HbA1c) reflects patient's glycemic status over the previous 3 months. Previous studies have reported that iron deficiency may elevate A1C concentrations, independent of glycemia. This study is aimed to analyze the effect of iron deficiency anemia on HbA1c levels in diabetic population having plasma glucose levels in control.

METHODS

Totally, 120 diabetic, iron-deficient anemic individuals (70 females and 50 males) having controlled plasma glucose levels with same number of iron-sufficient non-anemic individuals were streamlined for the study. Their data of HbA1c (Bio-Rad D-10 HPLC analyzer), ferritin (cobas e411 ECLIA hormone analyzer), fasting plasma glucose (FPG, Roche Hitachi P800/917 chemistry analyzer), hemoglobin (Beckman Coulter LH780), peripheral smear examination, red cell indices, and medical history were recorded. Statistical analysis was carried out by student's t-test, Chi-square test, and Pearson's coefficient of regression.

RESULTS

We found elevated HbA1c (6.8 ± 1.4%) in iron-deficient individuals as compared to controls, and elevation was more in women (7.02 ± 1.58%). On further classification on the basis of FPG levels, A1C was elevated more in group having fasting glucose levels between 100-126 mg/dl (7.33 ± 1.55%) compared to the those with normal plasma glucose levels (<100 mg/dl). No significant correlation was found between HbA1c and ferritin and hemoglobin.

CONCLUSION

This study found a positive correlation between iron deficiency anemia and increased A1C levels, especially in the controlled diabetic women and individuals having FPG between 100-126 mg/dl. Hence, before altering the treatment regimen for diabetic patient, presence of iron deficiency anemia should be considered.

HbA1c and iron deficiency: a review

Conditions that affect erythrocyte turnover influence HbA1c concentrations and the International Expert Committee has warned clinicians to be aware of any conditions that could affect the turnover of red blood cells. Although many forms of anemia are associated with lowering of HbA1c, iron deficiency has been shown to shift HbA1c slightly upward. The exact mechanism through which iron deficiency anemia affects HbA1c levels, however still remains unclear. The explanations provided above are merely speculations, warranting further studies to confirm and elucidate the role of these factors. As little work has been done in this field so future and large scale studies are required which may address HbA1c enhancing effect and the mechanism of increased HbA glycation in iron deficiency properly.

Determinants of HbA1c in nondiabetic Dutch adults: genetic loci and clinical and lifestyle parameters, and their interactions in the Lifelines Cohort Study

OBJECTIVES

Glycated haemoglobin (HbA1c) is associated with cardiovascular disease risk in individuals without diabetes, and its use has been recommended for diagnosing diabetes. Therefore, it is important to gain further understanding of the determinants of HbA1c. The aim of this study was to investigate the effects of genetic loci and clinical and lifestyle parameters, and their interactions, on HbA1c in nondiabetic adults.

DESIGN

Population-based cohort study.

SETTING

Three northern provinces of the Netherlands.

SUBJECTS

A total of 2921 nondiabetic adults participating in the population-based LifeLines Cohort Study.

MEASUREMENTS

Body mass index (BMI), waist circumference, HbA1c, fasting plasma glucose (FPG) and erythrocyte indices were measured. Data on current smoking and alcohol consumption were collected through questionnaires. Genome-wide genotyping was performed, and 12 previously identified single-nucleotide polymorphisms (SNPs) were selected for replication and categorized as 'glycaemic' and 'nonglycaemic' SNPs according to their presumed mechanism(s) of action on HbA1c. Genetic risk scores (GRSs) were calculated as the sum of the weighted effect of HbA1c-increasing alleles.

RESULTS

Age, gender, BMI, FPG, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, current smoking and alcohol consumption were independent predictors of HbA1c, together explaining 26.2% of the variance in HbA1c, with FPG contributing 10.9%. We replicated three of the previously identified SNPs and the GRSs were also found to be independently associated with HbA1c. We found a smaller effect of the 'nonglycaemic GRS' in females compared with males and an attenuation of the effect of the GRS of all 12 SNPs with increasing BMI.

CONCLUSIONS

Our results suggest that a substantial portion of HbA1c is determined by nonglycaemic factors. This should be taken into account when considering the use of HbA1c as a diagnostic test for diabetes.

Influence of iron metabolism indices on HbA1c in non-diabetic pregnant women with and without iron-deficiency anemia: effect of iron supplementation

AIMS

Condition that influence erythrocyte turnover also affect HbA1c. Although many forms of anemia are associated with lowering of HbA1c, iron-deficiency anemia (IDA) tends to increase HbA1c. In this study, we examined the relationship between HbA1c and erythrocyte indices in non-diabetic pregnancy and assessed the effect of iron supplementation on HbA1c.

MATERIALS AND METHODS

150 women were studied (30 non-diabetic), non-pregnant, non-anemic women in child bearing women with varying parity as controls (Gp 1); 30 non-diabetic, non-anemic pregnant women in first trimester of pregnancy (Gp 2a); 30 non-diabetic, non-anemic pregnant women in second trimester of pregnancy (Gp 2b); 30 non-diabetic, non-anemic pregnant women in third trimester of pregnancy (Gp 2c) and 30 non-diabetic pregnant women with IDA (Gp 2d). HbA1c, OGTT, erythrocyte indices and iron metabolic indices were determined in Gp 2d subjects not supplemented with iron and repeated these indices after 3 months of iron-supplementation.

RESULTS

The mean fasting and postprandial blood glucose levels (79.9±8.0mg/dl, 108.1±14.1mg/dl) in Gp 1 were found to be significantly lower in first trimester among Gp 2a (74.4±5.3mg/dl and 97.2±11.1mg/dl), in second trimester among Gp 2b (76.2±5.2mg/dl and 103.4±7.9mg/dl) followed by increase in IIIrd trimester among Gp 2c (82.3±5.7mg/dl and 112.5±8.5mg/dl) subjects. A significant difference in HbA1c was also observed among the groups (HbA1c 4.7±0.3% in Gp 1; 4.6±0.4% in Gp 2a; 4.5±0.3 in Gp 2b; 4.7±0.3 in Gp 2c). Among Gp 2d subjects, HbA1c was 5.2±0.3% and the level decreased after iron supplementation to 5.1±0.3%. Significant correlation between erythrocyte indices, iron metabolic indices and HbA1c was also observed.

CONCLUSION

We conclude that consideration should be given for performing glucose testing in patients with IDA to ascertain the reliability of HbA1c in the diagnosis of diabetes. HbA1c concentrations in diabetic patients with IDA should be interpreted with caution.

Spuriously high prevalence of prediabetes diagnosed by HbA(1c) in young indians partly explained by hematological factors and iron deficiency anemia

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.

Reduction in glycated albumin can predict change in HbA1c: comparison of oral hypoglycaemic agent and insulin treatments

AIM

To investigate whether the change in glycated albumin 3 weeks after initiating anti-diabetes treatment (oral hypoglycaemic agent or insulin) could predict the corresponding change in HbA(1c) 3 months later in Korean patients with Type 2 diabetes.

METHODS

A total of 140 patients were enrolled into two groups: group I (insulin-based; n = 100) and group II (oral hypoglycaemic agent-based; n = 40). Both glycated albumin and HbA(1c) levels were measured as 'glucose control markers' during hospitalization. Glycated albumin was measured again at 3 weeks (first visit) after the initial measurement, and HbA(1c) was measured at 3 months (second visit) after the initial measurement.. The change in glucose control marker was defined as 100 × (follow-up glucose control marker--hospital glucose control marker)/hospital glucose control marker.

RESULTS

In both groups, the change in glycated albumin at the first visit and in HbA(1c) at the second visit showed a moderate linear relationship (r = 0.735; P < 0.01). In group II (r = 0.778; P < 0.01), a slightly stronger linear relationship was demonstrated than in group I (r = 0.738; P < 0.001); however, there was no statistically significant difference between the two groups. A correlation coefficient between the change in glycated albumin and HbA(1c) was not affected by sex, age, BMI, haemoglobin, serum creatinine or albumin.

CONCLUSION

The reduction in glycated albumin 3 weeks after the initiation of treatment corresponded with the reduction in HbA(1c) 3 months after starting treatment in both the group treated with a oral hypoglycaemic agent and the insulin-treated group of Korean patients with Type 2 diabetes.

Is there a relationship between mean blood glucose and glycated hemoglobin?

Measurement of hemoglobin A1c (HbA1c) is considered the gold standard for monitoring chronic glycemia of diabetes patients. Hemoglobin A1c indicates an average of blood glucose levels over the past 3 months. Its close association with the risk for the development of long-term complications is well established. However, HbA1c does not inform patients about blood glucose values on a daily basis; therefore, frequent measurements of blood glucose levels are necessary for the day-to-day management of diabetes. Clinicians understand what HbA1c means and how it relates to glucose, but this is not the case with patients. Therefore, the translation of the HbA1c results into something more familiar to patients seemed a necessity. The scope of this article is to review the literature to search for enough scientific evidence to support the idea of a close relationship between HbA1c and mean blood glucose (MBG), and to justify the translation of HbA1c into something that reflects the MBG. Most studies confirm a close relationship between HbA1c and MBG, although different studies result in different linear equations. Factors affecting this relationship may limit the usefulness and applicability of a unique mathematical equation to all diabetes populations.

Influence of iron metabolism indices on glycated haemoglobin but not glycated albumin levels in premenopausal women

We have recently shown that in premenopausal women without anaemia, glycated haemoglobin (HbA(1C)) is inversely associated with mean corpuscular haemoglobin (MCH). Based on the hypothesis that iron deficient state (IDS) due to menstruation may influence erythrocyte metabolism and thereby HbA(1C) levels, we examined the relation of iron metabolism indices with HbA(1C) in premenopausal women. HbA(1C), serum glycated albumin (GA) and iron metabolism indices were determined in 104 premenopausal women with normal glucose tolerance. Among them, 17 were diagnosed with iron deficiency anaemia (IDA) and 30 with IDS. The other 57 subjects were diagnosed with normal iron state (NIS). HbA(1C) levels showed significant inverse association with serum iron, serum transferrin saturation and serum ferritin in 104 study participants. Multivariate regression analysis identified serum ferritin as negatively associated with HbA(1C). These were also observed in 87 premenopausal women without IDA. HbA(1C) levels in IDA subjects and in IDS subjects were higher than it in NIS subjects, while GA levels were not different among the three groups of subjects. In conclusions, iron metabolism indices influence HbA(1C) levels, but not serum GA levels, in premenopausal women.

Association between iron deficiency and A1C Levels among adults without diabetes in the National Health and Nutrition Examination Survey, 1999-2006

OBJECTIVE

Iron deficiency has been reported to elevate A1C levels apart from glycemia. We examined the influence of iron deficiency on A1C distribution among adults without diabetes.

RESEARCH DESIGN AND METHODS

Participants included adults without self-reported diabetes or chronic kidney disease in the National Health and Nutrition Examination Survey 1999-2006 who were aged > or =18 years of age and had complete blood counts, iron studies, and A1C levels. Iron deficiency was defined as at least two abnormalities including free erythrocyte protoporphyrin >70 microg/dl erythrocytes, transferrin saturation <16%, or serum ferritin < or =15 microg/l. Anemia was defined as hemoglobin <13.5 g/dl in men and <12.0 g/dl in women.

RESULTS

Among women (n = 6,666), 13.7% had iron deficiency and 4.0% had iron deficiency anemia. Whereas 316 women with iron deficiency had A1C > or =5.5%, only 32 women with iron deficiency had A1C > or =6.5%. Among men (n = 3,869), only 13 had iron deficiency and A1C > or =5.5%, and only 1 had iron deficiency and A1C > or =6.5%. Among women, iron deficiency was associated with a greater odds of A1C > or =5.5% (odds ratio 1.39 [95% CI 1.11-1.73]) after adjustment for age, race/ethnicity, and waist circumference but not with a greater odds of A1C > or =6.5% (0.79 [0.33-1.85]).

CONCLUSIONS

Iron deficiency is common among women and is associated with shifts in A1C distribution from <5.5 to > or =5.5%. Further research is needed to examine whether iron deficiency is associated with shifts at higher A1C levels.

A1C but not serum glycated albumin is elevated because of iron deficiency in late pregnancy in diabetic women

OBJECTIVE We have already reported that A1C is elevated because of iron deficiency in late pregnancy among nondiabetic pregnant women. This report examined whether the same phenomenon is observed in pregnant women with diabetes. RESEARCH DESIGN AND METHODS This longitudinal study was conducted in 17 pregnant women with diabetes (20-35 weeks of pregnancy). A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were measured. RESULTS A1C levels were significantly increased in late pregnancy, whereas serum glycated albumin showed no significant changes. Glycated albumin/A1C ratio, mean corpuscular hemoglobin, serum transferrin saturation, and serum ferritin were significantly decreased in late pregnancy. Serum transferrin saturation showed a significant positive correlation with glycated albumin/A1C ratio. CONCLUSIONS A1C levels, but not serum glycated albumin levels, are elevated in late pregnancy because of iron deficiency in diabetic women. Serum glycated albumin may offer an adequate marker for glycemic control during pregnancy.

Clinical impact of glycated albumin as another glycemic control marker

It is known that glycation among various proteins is increased in diabetic patients compared with non-diabetic subjects. Currently, among these glycated proteins, glycated hemoglobin (HbA(1C)) is used as the gold standard index of glycemic control in clinical practice for diabetes treatment. However, HbA(1C) does not accurately reflect the actual status of glycemic control in some conditions where plasma glucose changes during short term, and in patients who have diseases such as anemia and variant hemoglobin. In comparison, another index of glycemic control, glycated albumin (GA), more accurately reflects changes in plasma glucose during short term and also postprandial plasma glucose. Although GA is not influenced by disorders of hemoglobin metabolism, it is affected by disorders of albumin metabolism. This review summarizes diseases and pathological conditions where GA measurement is useful. These include the status of glycemic control changes during short term, diseases which cause postprandial hyperglycemia, iron deficiency anemia, pregnancy, chronic liver disease (liver cirrhosis), chronic renal failure (diabetic nephropathy), and variant hemoglobin.

A1C underestimates glycemia in HIV infection

OBJECTIVE

The objective of this study was to determine the relationship between A1C and glycemia in HIV infection.

RESEARCH DESIGN AND METHODS

We completed a prospective cross-sectional study of 100 HIV-infected adults with type 2 diabetes (77%) or fasting hyperglycemia (23%) with measured glucose, A1C, mean corpuscular volume (MCV), and fructosamine. A total of 200 HIV-uninfected type 2 diabetic subjects matched for key demographic characteristics served as control subjects.

RESULTS

Relative to the control subjects, A1C underestimated glucose by 29 +/- 4 mg/dl in the HIV-infected subjects. Current nucleoside reverse transcriptase inhibitors (NRTIs), higher MCV and hemoglobin, and lower HIV RNA and haptoglobin were associated with greater A1C-glucose discordance. However, only MCV and current NTRI use, in particular abacavir, remained significant predictors in multivariate analyses. Fructosamine more closely reflected glycemia in the HIV-infected subjects.

CONCLUSIONS

A1C underestimates glycemia in HIV-infected patients and is related to NRTI use. Use of abacavir and increased MCV were key correlates in multivariate analyses. Fructosamine may be more appropriate in this setting.