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Year : 2014  |  Volume : 2  |  Issue : 2  |  Page : 105-108

High HbA1C in anemic patients: Is hypovitaminosis D that link?

Department of Biochemistry, Kasturba Medical College, Manipal University, Manipal, Karnataka, India

Date of Web Publication17-Nov-2014

Correspondence Address:
Krishnananda Prabhu
Department of Biochemistry, Kasturba Medical College, Manipal University, Manipal - 576 104, Karnataka
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Source of Support: Manipal University, Conflict of Interest: None

DOI: 10.4103/2348-0149.144846

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Context: Glycated hemoglobin is a form of hemoglobin that is measured primarily to identify the average plasma glucose concentration over prolonged periods of time, formed due to non-enzymatic glycation. Previous studies have suggested increased glycated hemoglobin levels in anemic patients despite the shortened life span of the erythrocytes. Several reports have suggested an active role of vitamin D in the functional regulation of pancreatic β-cells. Hypovitaminosis D may be an independent risk factor for type 2 diabetes mellitus (T2DM) with higher HbA1c levels. Studies have also demonstrate association of vitamin D deficiency and greater risk of anemia in children. Aims: The aim of this study is to estimate and analyse hemoglobin A1c, vitamin D and hemoglobin levels in non diabetic anemic adults and assess the relationship between above mentioned parameters. Materials and Methods: The study was conducted at Kasturba Medical College, Manipal. Serum vitamin D, hemoglobin and HbA1c measured in 187 non-diabetic anemic adults of 25-55 years of age, glycated hemoglobin measured in BIORAD variant turbo II using ion exchange HPLC method, and vitamin D by Eletrochemiluminescene method. Hemoglobin estimation was done by Drabkin's method. Results and Conclusion: The study found negative correlation between vitamin D and HbA1c in both males and females (r = -0.5, r = -0.4 P ≤ 0.001), HbA1c and hemoglobin (r = -0.4, r = -0.3 P ≤ 0.002). Also, there was significant positive correlation between the vit D and hemoglobin (r = 0.4, r = 0.3 P ≤ 0.001) values in the study population. Thus, there could be a role of vitamin D in the management of anemia. Since the sample size was small further study is recommended with larger sample size for reliable results.

Keywords: Anaemia, glycated haemoglobin, non diabetic, vitamin D

How to cite this article:
Datta P, Belle VS, Singh K, Prabhu K. High HbA1C in anemic patients: Is hypovitaminosis D that link? . Niger J Exp Clin Biosci 2014;2:105-8

How to cite this URL:
Datta P, Belle VS, Singh K, Prabhu K. High HbA1C in anemic patients: Is hypovitaminosis D that link? . Niger J Exp Clin Biosci [serial online] 2014 [cited 2021 May 12];2:105-8. Available from: https://www.njecbonline.org/text.asp?2014/2/2/105/144846

  Introduction Top

Glycated hemoglobin is produced by a non enzymatic reaction between glucose and the N-terminal valine of both ί-chains of the hemoglobin molecule. The major form of glycated hemoglobin is hemoglobin A1c (HbA1c). [1],[2]. When plasma glucose is persistently elevated, the non-enzymatic glycation of hemoglobin increases. So it reflects the glycemic history over the previous 2-3 months, since erythrocytes have an average lifespan of 120 days. [3],[4] The HbA1c fraction is abnormally elevated in patients with chronic hyperglycemic diabetes mellitus and it correlates positively with the metabolic control. [5] According to the American Diabetes Association (ADA) guidelines, the value of HbA1c should be kept below 7% in all the diabetics. [6] The values which are greater than 7% indicate an increased chance of progression to the diabetic complications, especially the micro vascular ones.

However, certain studies have proven that the HbA1c levels are altered by other coexisting factors, along with diabetes. They are also altered in hemolytic anemia, [7] hemoglobinopathies, [8] acute and chronic blood loss, [9] pregnancy, [10] and uremia. [11]

In addition to its role in regulation of bone and mineral metabolism, vitamin D has been implicated in a wide array of biological actions including muscle strengthening, [12] cellular proliferation and differentiation, [13] immune system modulation, [14] inhibition of renin synthesis, [15] and insulin production. [16] Vitamin D has been demonstrated to affect marrow function. [17]

Moreover, levels of 1, 25 hydroxyvitamin D (the active form of vitamin D) are several hundred-fold higher in bone marrow compared with plasma. [18] Despite these intriguing observations, there is overall paucity of clinical studies investigating whether adequacy of vitamin D affects blood hemoglobin (Hb) levels.

Initial studies by Sluiter et al., [19] and Mitchell et al., [20] revealed a relationship between iron deficiency anaemia and HbA1c levels and attempted to explain the alteration in HbA1c levels in iron deficiency anaemia on the basis of both modifications to the structure of hemoglobin and levels of HbA1c in old and new red blood cells. But there are no studies of vitamin D status on adult patients who are anemic but not diagnosed with iron deficiency, vitamin B12 deficiency or chronic diseases.

Study on children and adolescents in National Health and Nutrition Examination Survey USA showed children with vitamin D levels below 30 ng/ml were nearly twice as likely to have anemia as those with normal vitamin D levels.

Therefore, since no such studies had been conducted on the Indian adult anemic population, we conducted the current study to check the effects of anemia on HbA1c levels in Indian patients, and also to evaluate the existence of any association between vitamin D with anemia.

The objective of the present study was to determine whether vitamin D is responsible for the increased HbA1c levels among the anaemic patients without diabetes.


The aim of this study was to estimate and analyse HbA1c and vitamin D level in non-diabetic, anemic adults.

Study subjects

Between March 2013 to August 2013, 187 non diabetic individuals of 25-55years age-group, who had anemia (Hb male <12 g/dl and Female <11 g/dl) and without history of prior history of diabetes.

Exclusion criteria

Patients suffering from mal-absorption, pregnant women, patients of significant cardiac, hepatic, renal, oncologic diseases, iron deficiency anemia.

Any glucose tolerance abnormalities (impaired glucose tolerance or diabetes mellitus), hemoglobinopathies, hemolyticanemia, chronic alcohol ingestion, and chronic renal failure, post-surgery patient, history of recent blood transfusion and those on long term medications which affects these parameters were excluded from the study.

Ethical statement

Ethics clearance was obtained prior to data collection from the institutional ethics committee Kasturba Hospital, Manipal University, Manipal, India. Consent was obtained from all the study individuals before the collection of blood sample.

Sample collection

After an overnight fast, using aseptic precautions 4 ml of venous blood samples were collected in red and lavender capped vaccutainer. Red capped vaccutainers were used for estimation of total vitamin D and hemoglobin and lavender vaccutainer used for hemoglobin and HbA1c.


Total serum vitamin D assay was estimated by Electrochemiluminesence method. HbA1cwas measured in BIORAD variant turbo II using ion exchange HPLC method. Hemoglobin estimation was done by Drabkin's s modified cyanomethemoglobin method.

Statistical analysis

Data was compiled and statistical evaluation was done using Statistical Package for the Social Sciences (SPSS) 16.0 Chicago SPSS Inc. Data were expressed as mean ± standard deviation (SD). Spearman's correlation coefficient was performed to look for correlations between variables. P value < 0.01 taken as significant.

  Results Top

In our study we found Hemoglobin levels in male to be (N = 91) 10.5 ± 2.8 g/dl and in females (N = 96) 9.1 ± 1.25 g/dl.

Vitamin D levels were in males 22.6 ± 10.8 ng/ml and in females 17.1 ± 8.5 ng/ml. Glycated Hb level were male 6.52 ± 1.13 females 6.4 ± 1.7 [Table 1].
Table 1: Result of comparison between different parameters in males and females

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Vitamin D levels are directly proportional with hemoglobin levels. As vitamin D levels are increasing hemoglobin values are increasing.

Hemoglobin levels are inversely correlated with HbA1c levels in study population.

Vitamin D levels are inversely correlation with HbA1c levels. As Vitamin D levels are decreasing HbA1c values are increasing.

  Discussion Top

In the present study we confirmed a significant inverse correlation between HbA1C and serum vitamin D level in both male (r = −0.5) and female (r = −0.4). The study findings that a high vitamin D status protects against diabetes in anemic patients as we got negative correlation which was significant in both male and female patients. In this regard, the need to identify the required daily intake of vitamin D should include the possible effect on reducing the risk of type 2 diabetes.

Thereby suggesting a protective role of vitamin D against the development of the disease, as suggested previously by Knekt P. [21]

This study demonstrates a prevalence and risk of anemia in individuals with D deficiency compared with those with normal D levels.

Cross-sectional study of 10,410 children and adolescents ages 1-21 years from the 2001-2006 National Health and Nutrition Examination Survey in USA shows Kids with vitamin D levels below 30 ng/ml were nearly twice as likely to have anemia as those with normal vitamin D levels. [22]

Vitamin D appears to be associated with anemia, one possibility is that vitamin modulates the level of systemic cytokine production thus reducing the inflammatory milieu that leads to anemia of chronic disease. Both in vivo and in vitro studies have demonstrated that calcitriol (1, 25 hydroxyvitamin D) reduces cytokine production. [18]

Another possible mechanism is that vitamin D directly stimulates erythroid precursors. Vitamin D receptors have been discovered in numerous non-renal target tissues including the bone marrow. [17] Normalizing tissue vitD25 levels may provide an adequate substrate for local tissue production of 1, 25 hydroxyvitamin D [25(OH) D] in hematopoietic tissues via extra-renal tissue activity of the 1alphahydroxylaseenzyme. Hematons (the buffy coat of bone marrow containing erythroid precursors, fibroblast, endothelial cells, lipid laden cells and macrophages) have been demonstrated to contain significantly higher concentrations of 1, 25-hydroxyvitamin D levels than bone marrow. [23]

Alemzadeh et al., found a significant relationship between 25(OH) D and HbA1c in Caucasians but not in African Americans. [24] This study concluded that the association between vitamin D status and HbA1c is age dependent. These studies may also reflect a role of ethnicity in this relationship.

Vitamin D has been shown to have a role in insulin production, secretion and insulin resistance. In recent years it has become apparent that for optimal functioning of many organs and tissues throughout the body adequate levels of Vitamin D is also important. Vitamin D receptors are identified in heart, smooth muscle, islets cells of pancreas which secretes insulin and immune cells. It has been also demonstrated that Islets cells of pancreas and immune cells possesses 1 α hydroxylase enzyme required for synthesis of vitamin D, vitamin D receptor and vitamin D dependent calcium binding proteins suggesting an important role of vitamin D in insulin secretion.

Further studies with larger numbers of participants are needed to elucidate the relation between vitamin D and the mechanism of anemia. Randomized clinical intervention studies are required to elucidate the impact of vitamin D on the risk of type 2 diabetes.


Small sample size. Patients were not recruited in a random manner as it is a hospital based study, so selection bias cannot be excluded.

  Conclusion Top

Study results showed that anaemia is associated with higher proportions of HbA1c, which could cause problem in the diagnosis of uncontrolled diabetes mellitus in anaemic patients. The vitamin D status must be considered during the interpretation of the HbA1c concentrations in diabetes mellitus.

  Acknowledgement Top

We are grateful to the Dean, Kasturba Medical College, Manipal for providing the facilities for conducting the study.

  References Top

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Knekt P, Laaksonen M, Mattila C, Harkanen T, Marniemi J Heliovaara M, et al. Serum vitamin D and subsequent occurrence of type 2 diabetes. Epidemiology 2008;19:666-7.  Back to cited text no. 21
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Aucella F, Scalzulli RP, Gatta G, Vigilante M, Carella AM, Stallone C. Calcitriol increases burst-forming unit-erythroid proliferation in chronic renal failure, a synergistic effect with r-HuEpo. Nephron Clin Pract 2003;95:121-7.  Back to cited text no. 23
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  [Table 1]


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