|Year : 2013 | Volume
| Issue : 3 | Page : 129-134
Evaluation of selected trace elements in male type 2 diabetic patients in Nnewi, south eastern Nigeria
Christian Ejike Onah1, Samuel Chukwuemeka Meludu2, Chudi Emmanuel Dioka3, Ubuo Kalu Amah3, John Ekenedirichukwu Okwara3, Charles Ukachukwu Osuji4
1 Department of Chemical Pathology, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria
2 Department of Human Biochemistry, Faculty of Basic Medical Sciences; Department of Chemical Pathology, Faculty of Medicine, Nnamdi Azikiwe University, Nnewi Campus, Nigeria
3 Department of Chemical Pathology, Faculty of Medicine, Nnamdi Azikiwe University, Nnewi Campus, Nigeria
4 Department of Internal Medicine, Faculty of Medicine, Nnamdi Azikiwe University, Nnewi Campus, Nnewi, Nigeria
|Date of Web Publication||30-Oct-2013|
Christian Ejike Onah
Department of Chemical Pathology, Nnamdi Azikiwe University Teaching Hospital, Nnewi
Background: There is accumulating evidence that the metabolism of several trace elements is altered in type 2 diabetic patients.
Aims: We, therefore, investigated the levels of some of the trace elements in serum of male type 2 diabetic patients with a view to establishing their metabolic status in these subjects.
Materials and Methods: One hundred and twenty-five male type 2 diabetic subjects and 50 apparently healthy non-diabetic male individuals within the age range of 32 - 70 years were recruited for this study. Fasting plasma glucose (FPG), trace elements (zinc, selenium, manganese and chromium), and body mass index (BMI) were determined.
Results: The mean levels of Zn, Mn, Se and Cr were significantly lower in serum of type 2 diabetic patients when compared with non-diabetic controls (P < 0.001). Expectedly, the mean level of FPG in diabetic subjects was significantly higher when compared with the healthy controls (P < 0.001) however, there was no significant different in the level of BMI (P > 0.05). This study also observed a significant negative correlation between the serum levels of Trace Elements (Zn, Se, Cr and Mn) and the FPG in diabetic subjects.
Conclusion: Consequently, the decrease in levels of trace elements may play a role in pathogenesis of diabetes mellitus considering their roles in glucose metabolism. Therefore, proper dietary control and mineral supplementation is advised.
Keywords: Metabolism, pathogenesis, supplementation, trace elements, Type 2 diabetes mellitus
|How to cite this article:|
Onah CE, Meludu SC, Dioka CE, Amah UK, Okwara JE, Osuji CU. Evaluation of selected trace elements in male type 2 diabetic patients in Nnewi, south eastern Nigeria. J Health Spec 2013;1:129-34
|How to cite this URL:|
Onah CE, Meludu SC, Dioka CE, Amah UK, Okwara JE, Osuji CU. Evaluation of selected trace elements in male type 2 diabetic patients in Nnewi, south eastern Nigeria. J Health Spec [serial online] 2013 [cited 2020 Jun 6];1:129-34. Available from: http://www.thejhs.org/text.asp?2013/1/3/129/120848
| Introduction|| |
Diabetes mellitus is a metabolic disorders of carbohydrate metabolism in which glucose is underused, producing hyperglycaemia.  Diabetes affects over 150 million people worldwide and this number is expected to double by 2025,  90% of whom are type 2.  As the disease progresses, patients are at increased risk for the development of specific complications, including retinopathy leading to blindness, nephropathy leading to renal failure, neuropathy (nerve damage), and atherosclerosis. 
The International Diabetes Federation (IDF) estimated in 2012 that 366 million adults, aged 20 - 79 years, out of the world's 7 billion population have diabetes. This gives a comparative prevalence of 8.5%. In Africa, over 4.3% are estimated to have diabetes while 81.2% of Africans with diabetes are undiagnosed. This region has the highest mortality rate due to diabetes and it has been estimated that over the next 20 years, the number of people with diabetes in the region will almost double. According to the WHO standard, Nigeria has a comparative prevalence of 4.83% with over 88,681 diabetes-related deaths.  The work done by Osuji et al, on the prevalence of diabetes mellitus in a group of women attending "August meeting" at Naze South East Nigeria put the prevalence of diabetes at 6.7%. 
Trace elements are inorganic molecules which are essential for life. Although these elements constitute a relatively small amount of total body tissues, they are very essential in many physiological and biochemical processes. In states of absolute deficiency, death results and in limited intake biological functions are impaired.  Studies have shown that the metabolism of several essential trace elements is altered in diabetes and that these nutrients might have specific roles in the pathogenesis, complications and progress of this disease. 
Zinc (Zn) is an essential trace element that plays a vital role in maintaining many biological processes and cellular homeostasis. Zn plays a key role in the synthesis, secretion and action of insulin in both physiological and pathophysiological states.  It also plays a critical structural role for antioxidant enzyme superoxide dismutase and can stabilize biological membranes to decrease their susceptibility to oxidative damage that can impair cell functions.  Manganese(II) ions function as cofactors for a large variety of enzymes with many functions.  Manganese (Mn) enzymes are particularly essential in detoxification of superoxide-free radicals in organisms that must deal with elemental oxygen. It also plays an essential part in sex hormone production, proper bone and cartilage formation, and glucose metabolism. 
Chromium (Cr) is a well-known component of the glucose tolerance factor, which is involved in normal carbohydrate and lipid metabolism. It acts primarily by regulating insulin action; that is in the presence of Cr in physiological form, much lower amounts of insulin are required, since Cr acts by increasing insulin efficiency.  The selenium (Se) role in preventing glucose intolerance and the complications of diabetes mellitus has also been postulated. For instance, insulin reserves are decreased with Se deficiency causing glucose intolerance.  Se is a potent antioxidant that acts as an anti-inflammatory agent and is required for immune system function.  The biological functions associated with Se include male fertility, prevention of cancer, cardiovascular disease, viral mutation, endocrine and immune function as well as modulating inflammatory response. 
In view of all these putative roles, one can envisage that diminished levels of these trace elements may increase the severity of this disease. However, previous study has shown that appropriate trace element supplementation might prove beneficial in ameliorating some physiological deficiencies associated with diabetes and prevent or retard secondary complications. 
Since medications, genetics, medical conditions, lifestyle and dietary habits have been identified as the leading cause of type 2 diabetes mellitus and with the changing lifestyle and dietary trends in Nigeria, the prevalence of diabetes mellitus is bound to keep increasing with increasing effects on the metabolism of these trace elements. However, data concerning the level of trace elements in diabetic patient in South East Nigeria particularly in Anambra state is very scanty, hence the significance of this study. This study therefore, seeks to investigate the levels of some trace elements in male type 2 diabetic patient in our environment.
| Materials and Methods|| |
Study design and population
This is a cross-sectional study designed to investigate the levels of trace elements in male type 2 diabetic patients and in non-diabetic controls. The study design received an approval from the Ethics Committee of Nnamdi Azikiwe University Teaching Hospital (NAUTH) Nnewi. The informed consents of all the participants were sorted and all the participants freely volunteered.
A total number of 175 participants were recruited for this study. The study population is 125 known type 2 diabetic male patients with mean age (51.58 ± 8.55) and age range (32 - 70 years) attending Nnamdi Azikiwe University Teaching Hospital (NAUTH), Nnewi (Eastern Nigeria) and 50 non-diabetic male individuals who are staff of the NAUTH, Nnewi with mean age (49.18 ± 11.46) and age range (32 - 70 years).
Among non-diabetic control group, those that are under mineral supplements, consume alcohol or smoke cigarette regularly or have any form of chronic illness such as hypertension, renal disease, heart problems, etc., were disqualified. Out of 53 control individuals that were finally selected three were disqualified based on their fasting plasma glucose that are above 7.0 mmol/L as recommended by WHO. 
All male patients with type 2 diabetes mellitus were considered eligible for this study, irrespective of age, duration of diabetes and treatment except those that take mineral supplements, drink alcohol or smoke cigarette regularly. The diagnosis of diabetes mellitus was made based on the World Health Organization criteria: two fasting glucose measurements above 7.0 mmol/L were considered diagnostic for diabetes mellitus.  Patients' medical history such as age, diabetes treatment and duration of diabetes were obtained. Their BMI were calculated using their measured height and weight.
The minimum sample size for the study was calculated using the formula when population is more than 10000. 
n = Z 2 pq/d 2
where n = minimum sample size; Z = standard normal deviation at 95% confidence interval is 1.96; P = proportion of the population estimated to have the public health problem under study (the prevalence of diabetes in Nigeria is 4.83%. 
Blood sample collection and biochemical analysis
Five millilitres of fasting venous blood samples were collected from all respondents for the analysis. A part was dispensed into fluoride oxalate bottles for glucose determination using standard enzymatic spectrophotometric method (Glucose Oxidase method). The remaining part was dispensed into a plain bottle and allowed to clot, retract and the serum stored at -20°C until analysis of trace elements using Atomic Absorption Spectrophotometric method.
Reference values for Trace Elements
Zn: up to 1000 mcg/l. 
Mn: 0.3 - 1.04 mcg/l. 
Se: 50 - 145 mcg/l. 
Cr: 0.05 - 0.48 mcg/l. 
The version 20 of Statistical Package for Social Sciences (SPSS) was used in statistical analysis. All data were expressed as the mean ± standard deviations. Association between two variables was determined using Pearson's correlation coefficient. Student's t-test was used when comparing two groups. Differences with P-values <0.05 were considered significant.
| Results|| |
One hundred and twenty-five diabetic patients were studied. Out of this number 91 (72.8%) were in oral hypoglycaemics, 15 (12.0%) were in insulin therapy and 19 (15.2%) were in combined therapy. The mean age and BMI of diabetic subjects were 51.58 ± 8.55 years and 25.31 ± 2.72 kg/m 2 respectively while that of control subjects were 49.18 ± 11.46 years and 25.1 ± 1.6 kg/m 2 respectively. The mean duration of diabetes (DDM) was 7.68 ± 5.73 years and the range was 1 - 22 years.
The results showed that the mean values of Zn, Mn, Se, and Cr were significantly lower in serum of diabetic patients when compared with the non-diabetic controls. Expectedly, the mean FPG was significantly higher in diabetic subjects when compared with the healthy controls. However, the mean BMI of the type 2 diabetic subjects was not significantly different to that of the healthy controls [Table 1].
|Table 1: Age, BMI, FPG, and Trace Elements (Zn, Mn, Se, and Cr) in Type 2 diabetic subjects and in non-diabetic controls|
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The BMI, age, and DDM did not show any significant correlation with the Trace Elements (Zn, Se, Mn and Cr) in both Type 2 diabetic subjects and non-diabetic controls except Zn that showed a moderately significant negative correlation with Age in Type 2 diabetic subjects [Table 2]. In the same way, the FPG did not show significant correlation with the Trace Elements in non diabetic control subjects [Table 2]; however, FPG showed significant negative correlation with Trace Elements in diabetic subjects [Figure 1], [Figure 2], [Figure 3] and [Figure 4].
|Figure 1: Association between FPG and Manganese in Type 2 diabetic subjects|
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|Figure 3: Association between FPG and Chromium in Type 2 diabetic subjects|
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|Figure 4: Association between FPG and Selenium in Type 2 diabetic subjects|
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|Table 2: Association between BMI, Age, DDM, FPG, and Trace elements in type 2 diabetic subjects and normal controls|
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| Discussion|| |
Interest in the clinical significance of trace element metabolism has been steadily increasing. Trace elements have important physiological effects when present at concentrations other than those associated with classical toxicity or with extreme deficiency.  There is accumulating evidence that the metabolism of several trace elements is altered in diabetes mellitus. ,
In this study, there was a significantly lower Zn level in diabetic subjects than in normal controls. This agrees with the works done by other researchers. ,,, Zn homoeostasis is mostly affected by hyperglycaemia which results in hyperzincuria or decreased gastrointestinal absorption of Zn or even both. El-Yazigi et al., evaluated both type 1 and type 2 diabetes and found that Zn excretion were greater in diabetes than in matched controls.  It has been postulated that hyperglycaemia interferes with the active transport of Zn back into the renal tubular cells. In dogs, experimentally-induced hyperglycaemia resulted in significant hyperzincuria.  In streptozotocin-induced diabetic rats, increased Zn excretion has been routinely observed.  Even when the hyperglycaemia was reduced by the administration of insulin, hyperzincuria had been reported to persist though on a reduced level. ,
However, some studies have suggested a defect in Zn absorption associated with hyperglycaemia or diabetes. Kinlaw et al., demonstrated abnormal Zn tolerance tests in diabetic patients suggestive of decreased absorption.  Escobar et al also demonstrated a down regulation of fractional Zn transport which may be related to increased production of metallothionein in diabetics.  In relation to insulin, Quarteman demonstrated that diet induced Zn deficiency in rats, resulted in a decreased ability of the pancreas to secrete insulin in response to a glucose load.  Thereafter, Boquist et al., demonstrated a decrease in glucose tolerance with no change in insulin production in Zn-deficient hamsters in response to an intra-venous glucose load.  These suggest that Zn deficiency may reduce the ability of the pancreas to secret insulin in response to a glucose load.
Cr increases glucose tolerance by enhancing insulin efficiency.  This present study showed a significant decrease in mean levels of serum Cr in type 2 diabetic subjects than in normal controls. This agreed with the work done by Anderson et al., which showed Cr deficiency in type 2 diabetic subjects.  The reduction in levels of Cr in type 2 diabetes might be due to high level of glucose since hyperglycaemia have been suggested to increase the excretion of Cr.  Thus, it may not be surprising to find an inverse relationship between serum Cr levels and FPG in type 2 diabetic subjects as noted in this study.
The significant decrease in Mn in this work is in line with the findings of Kazi et al., which showed significantly lower level of Mn in 257 type 2 diabetic when compared with 166 non-diabetic controls.  The lower blood Mn in type 2 diabetic subjects might be as a result of increased urinary excretion of Mn. This finding agrees with the works of some authors, who reported that urinary Mn excretion was higher in diabetics compared to non-diabetic controls.  This study also observed a significant negative correlation between the serum level of Mn and FPG in diabetic subjects which is in line with the work of Farid.  In addition, a study on functional Mn status showed that the activity of the antioxidant isoenzyme, Mn-superoxide Dismutase (MnSod), was lower in the white blood cells of diabetics than in non-diabetic controls.  This suggests a poor handling of superoxide's generated in diabetes mellitus and this may increase diabetes complications.
The significant lower Se level observed in this study also agreed with the work of Burt  and Akinloye et al.,  which showed significantly lower Se concentration in diabetic patients than in healthy control subjects. Se acts as an antioxidant and peroxynitrite scavenger when incorporated into selenoprotein. It is the main element in glutathione peroxidase (an antioxidant) that reduces formation of free radicals and peroxidation of lipoproteins. The low concentration of Se and other relevant antioxidants in serum could potentially expose the subject to oxidative stress which is known to be associated with the pathogenesis of diabetes mellitus. Also, low Se level has been shown to reduce insulin secretion and increase insulin resistance, thereby possibly playing a role in the development and pathogenesis of type 2 diabetes. 
| Conclusions|| |
In this study we found that serum levels of Trace Elements (Zn, Se, Cr, and Mn) were significantly lower in type 2 diabetic patients than in non-diabetic controls while there was no significant difference in the levels of BMI in both type 2 diabetic subject and controls. This study also observed significant negative correlations between the serum levels of Trace Elements (Zn, Se, Cr and Mn) and the FPG in diabetic subjects. These observations might be as a result of poor glycaemic control. However, these observed low levels of Trace Elements in diabetics may play a role in the pathogenesis of diabetes mellitus considering their roles in glucose metabolism. Therefore, proper dietary control and mineral supplementation are advised. We advocate further clinical study that will involve larger study population and HbA 1c measurement with more sophisticated techniques in order to fully understand the role of Trace Elements in Type 2 diabetes mellitus.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]