Association of glycated hemoglobin with hemoglobin levels in elderly nondiabetic subjects

Relationship between glycosylated hemoglobin and iron deficiency anemia: A common but overlooked problem

INTRODUCTION

Both diabetes mellitus (DM) and iron deficiency anemia (IDA) are prevalent in every area of the world, and so, the possibility of these two diseases co-existing is also very high. It is our belief that clinical results of any correlation between iron status of the body and glycosylated haemoglobin (HbA1c) would be beneficial to many patients, therefore in this study, the effect of IDA on HbA1c was investigated.

MATERIALS - METHODS

A total of 146 patients with DM and IDA were evaluated prospectively. While the patients were administered 270 mg/day of ferrous sulphate (80 mg elemental iron) orally for three months for the treatment of IDA, no interventions were made for the treatment of DM. Patient levels of hemoglobin (Hb), hematocrit, red blood cells (RBC), mean corpuscular volume (MCV), platelet, white blood cells (WBC), serum iron, serum iron binding capacity (SIBC), ferritin, fasting plasma glucose (FPG), HbA1c, body mass index (BMI), C-reactive protein (CRP) values were measured at baseline and at the third month of treatment with iron, and were compared.

RESULTS

The median age of our patients was 45 (40-50) and median duration of diabetes was 3 years (1,75-5). While the baseline median Hb was 10.4 (mg/dL) (9.5-11.1), MCV was 74 (fL) (70.8-77), ferritin was 4 (ug/L) (3-6) at three months, Hb was measured at 12.6 (mg/dL) (12.1-13.2), MCV was measured at 82 (fL) (80-86), ferritin was measured at 15 (ug/L) (9-21.2) and was significantly higher compared to baseline values (p < 0.001). The baseline median HBA1c of patients was 7.09 ± 0.51 (%) and three month HBA1c was 6.69 ± 0.53 (%), which was significantly lower than when comparing baseline values with values at third month (p < 0.001). Baseline and three month values for FPG were 118 (mg/dL) (108-132) and 116 (mg/dL) (106-125) respectively, and there was no significant difference (p:0.07). A 2.2 mg/dL (1.5-3.5) increase in median Hb level accompanied a 0.4 % (0.2-0.6) decrease in median HbA1c levels (Spearman rho = -0.362; p < 0.001).

CONCLUSION

Our study has shown conclusivly that IDA is related to increased HbA1c concentrations and HbA1c decreases significantly following treatment with iron. IDA should be considered before making any decisions regarding diagnosis or treatment according to HbA1c.

Hemoglobin within normal range is negatively related to hemoglobin A1c in a nondiabetic American population aged 16 years and older

BACKGROUND

Protein glycosylated hemoglobin, hemoglobin A1c (HbA1c) binds hemoglobin (Hb) in red blood cells to blood glucose. However, the relationship between Hb and HbA1c remains unclear.

AIM

To elucidate their relationship in a nondiabetic population aged ≥ 16 years in the United States, using data from the 1999-2018 National Health and Nutrition Examination Survey.

METHODS

This study was based on data from 44560 adults aged ≥ 16 years, excluding those with diabetes. The relationship was estimated using a multivariate regression. We also used piecewise linear regression for subgroup analysis based on age and sex stratification and analysis of the threshold effects of Hb on HbA1c.

RESULTS

Hb and HbA1c levels were negatively correlated in the unadjusted model (β = -0.01; 95%CI: -0.01, -0.01). The correlation was significantly negative when the regression model was minimally regulated and stratified by age and sex, and remained negative when the model was further regulated (more than 10%) to identify covariates with the HbA1c level influence estimates. In subgroup analyses based on age and sex stratification, the association remained negative when the covariates were controlled. A nonlinear relationship was observed between them when the Hb levels reached the tipping point (13.2 g/dL) (adjusted odds ratio, -0.04; 95%CI: -0.05, -0.03) and when the Hb levels exceeded 13.2 g/dL (adjusted odds ratio, -0.10; 95%CI: -0.10, -0.09).

CONCLUSION

Our study shows that normal Hb levels are negatively correlated with HbA1c in nondiabetic Americans aged ≥ 16 years.

Determinants of Longitudinal Change of Glycated Hemoglobin in a Large Non-Diabetic Population

Although many cross-section studies have assessed the determinants of glycated hemoglobin (HbA_1c), there have been limited studies designed to evaluate the temporal correlates of HbA_1c in non-diabetic patients. This study aimed to identify the major determinants of longitudinal change of HbA_1c in non-diabetic patients. This study included subjects from the 104,451 participants enrolled between 2012 and 2018 in the Taiwan Biobank. We only included participants with complete data at baseline and follow-up (n = 27,209). Patients with diabetes at baseline or follow-up (n = 3983) were excluded. Finally, 23,226 participants without diabetes at baseline and follow-up were selected in this study. △Parameters was defined as the difference between the measurement baseline and follow-up. Multivariable linear regression analysis was used to identify the major determinants of HbA_1c longitudinal change (△HbA_1c). During a mean 3.8 year follow-up, after multivariable analysis, new-onset hypertension (coefficient β: 0.014, p < 0.001), high △heart rate (coefficient β: 0.020, p = 0.002), high △BMI (coefficient β: 0.171, p = 0.028), high △fasting glucose (coefficient β: 0.107, p < 0.001), low △creatinine (coefficient β: −0.042, p < 0.001), high △total cholesterol (coefficient β: 0.040, p < 0.001), high △hemoglobin (coefficient β: 0.062, p < 0.001), high △GPT (coefficient β: 0.041, p = 0.001), and low △albumin (coefficient β: −0.070, p < 0.001) were significantly associated with high △HbA_1c. In non-diabetic population, strategies to decrease the development of new-onset hypertension, resting heart rate, body mass index, fasting glucose, total cholesterol, and GPT and increase serum albumin level might be helpful in slowing the longitudinal change of HbA_1c. In addition, increased hemoglobin and decreased serum creatinine over time also had an impact on the HbA_1c elevation over time in non-diabetic population.

Association between hemoglobin within the normal range and hemoglobin A1c among Chinese non-diabetes adults

BACKGROUND

Hemoglobin A1c (HbA1c) is the product of a non-enzymatic chemical reaction between hemoglobin (Hb) and glucose. However, the association between Hb and HbA1c remains to be fully elucidated in view of the controversial findings reported to date. Therefore, our aim in this study was to evaluate the association between Hb levels within the normal range and HbA1c levels among Chinese non-diabetes adults using cross-sectional data from the China Health and Nutrition Survey 2009.

METHODS

Our analysis was based on the data of 1659 non-diabete adults 20-49 years of age. Multivariable linear models were applied to examine the association between Hb and HbA1c levels. Subgroup analyses stratified by age and sex were also performed.

RESULTS

The association between Hb and HbA1c levels was positive in the unadjusted model (β =0.020, 95% CI: 0.008, 0.032). However, this association did not remain significant when the regression model was minimally adjusted for age and sex (β =0.006, 95% CI: - 0.014, 0.024); this association became negative when the model was further adjusted for covariates whose effect estimates of HbA1c levels more than 10% (β = - 0.042, 95% CI: - 0.064, - 0.020). The association remained negative on subgroup analyses stratified by age (20-34 years: β = - 0.052, 95% CI: - 0.091, - 0.013; 35-49 years: β = - 0.041, 95% CI: - 0.068, - 0.014) and sex (men: β = - 0.042, 95% CI: - 0.074, - 0.010; women: β = - 0.042, 95% CI: - 0.073, - 0.012) when controlling for covariates.

CONCLUSIONS

Our findings revealed that Hb levels within the normal range were negatively associated with HbA1c levels among Chinese non-diabetes adults. Confounding factors, such as red blood cell counts can affect the association between Hb and HbA1c levels.

Use of proton pump inhibitors is associated with lower rates of first-time ischemic stroke in community-dwelling elderly

AIM

Data on cardiovascular outcomes in elderly using proton pump inhibitors (PPI) are scant. We aimed to test the association between PPI use and the occurrence of first-time ischemic stroke (FTIS) among elderly.

METHODS

The electronic database of a centrally located district branch of a large health maintenance organization in Israel was retrospectively screened (2002-2016) for community-dwelling individuals (≥65-95 years) for demographics and co-morbidities. Follow-up was until FTIS, death or end of study. Findings were analyzed by PPI use and occurrence of FTIS.

RESULTS

29,639 subjects (without history of stroke and use of antiplatelet aggregation drugs) mean age of 82.2 ± 5.5 years (range: 65-95 years, 38% male) were analyzed: 8,600 (29%) used PPIs. Mean follow up was 10.58 years (SD ± 5.44). Similar total and annual occurrence rates of FTIS were depicted in PPI users and non-users (20.9% vs. 21% and 2% vs. 2.1%, respectively). On a Cox regression analysis, upon adjustment for age, gender and cardiovascular disease related risk factors, PPI use was significantly associated with lower rates of FTIS (HR 0.73, 95% C.I. 0.69-0.77, p < 0.001). The risk for FTIS was significantly lower in subjects using PPI at any dose and for any time period compared to non-users (HR 0.9, 95% C.I. 0.85-0.96 for 7-48 yearly prescriptions and HR 0.51, 95% C.I. 0.46-0.55 for ≥49 yearly prescriptions).

CONCLUSIONS

PPI use was associated with lower rates of FTIS in community-dwelling elders. Prospective large-scale studies are needed to fully elucidate the effect of PPI in this aging population.

Associations of anemia and hemoglobin with hemoglobin A1c among non-diabetic workers in Japan

AIMS/INTRODUCTION

We examined the association between hemoglobin A1c (HbA1c) and anemia, which was categorized into three groups according to mean corpuscular volume (MCV), as well as the association between hemoglobin in the non-anemic range and HbA1c.

MATERIALS AND METHODS

We used the 2016 health checkup data from 36,422 workers without diabetes. Anemic people were divided into three groups based on MCV: <80, 80-90 and >90 fL. Non-anemic people were divided into four groups based on their hemoglobin levels. We carried out multiple linear regression models to estimate the means and 95% confidence intervals (CIs) of HbA1c.

RESULTS

For men, 0.2% had anemia with MCV <80 fL, 0.5% had anemia with MCV 80-90 fL, 0.9% had anemia with MCV >90 fL and 98.4% had no anemia. For women, the corresponding values were 6.1, 6.4, 2.8 and 84.7%, respectively. The adjusted mean HbA1c (%) values for men with anemia with MCV <80, 80-90 and >90 fL were 5.67 (95% CI 5.60-5.74), 5.58 (95% CI 5.54-5.62) and 5.41 (95% CI 5.37-5.44), respectively. Among men without anemia, HbA1c (%) increased from 5.36 (95% CI 5.34-5.39) in those with hemoglobin ≥17.5 mg/dL to 5.45 (95% CI 5.45-5.46) in those with hemoglobin 13.0 to <14.5 mg/dL (P for trend <0.001). The HbA1c values were higher in men with anemia with MCV <80 fL or MCV 80-90 fL, but lower in men with MCV >90 fL, compared with non-anemic men with hemoglobin 13.0 to <14.5 mg/dL (All P < 0.001). Similar findings were observed in women.

CONCLUSIONS

We observed elevated HbA1c among anemic people with MCV <80 fL or MCV 80-90 fL, and decreased HbA1c among anemic people with MCV >90 fL, suggesting that different types of anemia might influence HbA1c differently. In addition, non-anemic people with lower hemoglobin levels had higher HbA1c levels, suggesting that hemoglobin levels are in need of consideration when interpreting HbA1c values among non-anemic people.

The association and discordance between glycated hemoglobin A1c and glycated albumin, assessed using a blend of multiple linear regression and random forest regression

BACKGROUND

Due to a high prevalence of thalassemia in southwest China, the diagnostic value of glycated hemoglobin A1c (HbA1c) is limited in the local population. Glycated albumin (GA) must also be measured for glucose monitoring. We sought to explore the relationships between HbA1c and GA.

METHODS

We analyzed 3,414 participants and allocated to four groups: GA > 14% and HbA1c > 5.7% (group 1), GA > 14% and HbA1c ≤ 5.7% (group 2), GA ≤ 14% and HbA1c > 5.7% (group 3), and GA ≤ 14% and HbA1c ≤ 5.7% (group 4). We used stepwise multivariable logistic regression analysis to study the inconsistency of HbA1c and GA. Furthermore, we explored their association using multiple linear regression (MLR), random forest regression (RFR), and 3 blended models. Finally, we performed sensitivity analyses by changing the thresholds of HbA1c (6.5%) and GA (12% or 16%).

RESULTS

There were 934 participants in group 1, 86 in group 2, 964 in group 3, and 1,430 in group 4. Age, high-density lipoprotein-cholesterol concentration, and red blood cell count were associated with the discordance in HbA1c and GA values. We constructed an RFR model that included MLR predictions as independent variables and could explain 97.80% of the variance in HbA1c in the training set, and 91.65% in the cross-validation set. Our results remained robust in 3 sensitivity analyses.

CONCLUSIONS

HbA1c and GA values are inconsistent in the population we studied. A model that blends MLR and RFR can be used to correct HbA1c values when conflicting HbA1c and GA values are encountered in patients.

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.

Glycosylated Hemoglobin in Subjects Affected by Iron-Deficiency Anemia

Previous studies have suggested that iron-deficiency anemia affects glycosylated hemoglobin (HbA1c) measurements, but the results were contradictory. We conducted a retrospective case-control study to determine the effects of iron deficiency on HbA1c levels. Starting with the large computerized database of the Italian Hospital of Desio, including data from 2000 to 2016, all non-pregnant individuals older than 12 years of age with at least one measurement of HbA1c, cell blood count, ferritin, and fasting blood glucose on the same date of blood collection were enrolled. A total of 2,831 patients met the study criteria. Eighty-six individuals were diagnosed with iron-deficiency anemia, while 2,745 had a normal iron state. The adjusted means of HbA1c were significantly higher in anemic subjects (5.59% [37.37 mmol/mol]), than those measured in individuals without anemia (5.34% [34.81 mmol/mol]) (P<0.0001). These results suggest that clinicians should be cautious about diagnosing prediabetes and diabetes in individuals with anemia.

Iron reduction response and demographic differences between diabetics and non-diabetics with cardiovascular disease entered into a controlled clinical trial

Filings of elemental iron separated magnetically from a homogenate of breakfast cereal implicated in the risk of cardiovascular disease and diabetes.

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.