|Year : 2008 | Volume
| Issue : 1 | Page : 9-13
Comparison of serum glucose and salivary glucose in diabetic patients
Sreedevi1, MC Shashikanth2, P Shambulingappa3
1 Department of Oral Medicine & Radiology, I.T.S. Centre for Dental Studies and Research, Delhi-Meerut Road, Murad Nagar, Ghaziabad, India
2 Department of Oral Medicine & Radiology, U.P. Dental College, Lucknow, India
3 Department of Oral Medicine & Radiology, M.M. College of Dental Sciences & Research, Mullana (Ambala), Haryana, India
Department of Oral Medicine and Radiology, ITS Centre for Dental Studies and Research, Delhi-Meerut Road, Murad Nagar, Ghaziabad-201 206, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background and Objectives: The importance of saliva for oral health is well known. Diabetes mellitus affects the salivary gland functioning and thus alters the salivary constituents. For many years the question of the presence of glucose in saliva has been a subject of debate and only few people found correlation between serum glucose and salivary glucose in diabetics. Hence, the purpose of this study was to estimate and correlate salivary glucose concentration and serum glucose concentration in diabetics and healthy controls. Materials and Methods: 60 newly diagnosed diabetic patients and 60 age and sex matched control subjects were included in the study. Blood and saliva samples from both the groups were collected at least two hours after the breakfast. The samples were centrifuged and subjected to glucose analysis using Semiautoanalyzer (BioSystems BTS-310 Photometer). For experimental group, the samples were collected again after the control of diabetes mellitus. The statistical comparisons were performed using paired and unpaired t -test. Results: A highly significant correlation was found between salivary glucose and serum glucose before the treatment and also after the control of diabetes. The correlation between salivary glucose and serum glucose was also highly significant in controls. The levels of salivary glucose did not vary with age and sex. Conclusion and Interpretation: As there was significant correlation between salivary glucose and serum glucose, salivary glucose holds the potential of being a marker in diabetes. Further, it has an added advantage of being non-invasive procedure with no need of special equipments and with fewer compliance problems as compared with collection of blood.
Keywords: Diabetes mellitus, salivary glucose and serum glucose
|How to cite this article:|
Sreedevi, Shashikanth M C, Shambulingappa P. Comparison of serum glucose and salivary glucose in diabetic patients. J Indian Acad Oral Med Radiol 2008;20:9-13
|How to cite this URL:|
Sreedevi, Shashikanth M C, Shambulingappa P. Comparison of serum glucose and salivary glucose in diabetic patients. J Indian Acad Oral Med Radiol [serial online] 2008 [cited 2020 Jan 28];20:9-13. Available from: http://www.jiaomr.in/text.asp?2008/20/1/9/44354
| Introduction|| |
Saliva is a complex fluid, whose important role is to maintain the well-being of oral cavity.  Saliva can be gland specific saliva and whole saliva.  The average daily flow of saliva varies between 1 and 1.5 l. About 99% of saliva is water. The remaining 1% consists of most part of the large organic molecules (e.g.: proteins, glycoproteins and lipids), small organic molecules (e.g.: glucose and urea) and electrolytes (e.g.: sodium, calcium, chloride and phosphates etc.). Parotid glands produce a watery secretion. Submandibular gland and sublingual gland produces more viscous fluid than parotid gland. 
The importance of well functioning salivary glands for oral health is well known. Impaired flow rate, altered composition of saliva and increased oral microbial counts may increase the susceptibility to caries, periodontal disease and oral mucosal lesions. 
The composition and secretion of saliva is influenced by local as well as systemic, neurochemical, hormonal, nutritional and metabolic factors.  One such factors is diabetes mellitus which is known to alter the constitution and flow of saliva. The extent of alteration and its clinical significance has been explored by some researchers.
Saliva offers some distinctive advantages. Whole saliva can be collected non-invasively and by individuals with limited training. No special equipment is needed for collection of the fluid. Diagnosis of disease via the analysis of saliva is potentially valuable for children and older adults. Collection of fluid is associated with fewer compliance problems as compared with the collection of blood. Analysis of saliva can provide a cost-effective approach for screening of large populations. Saliva can be useful in the monitoring of therapeutic drug levels and detection of illicit drug use. Further, it may provide valuable information regarding certain endocrine disorders. 
A significant correlation between salivary glucose level and serum glucose level has been observed. ,, There is paucity of data on the utility of salivary glucose level during the treatment and monitoring of diabetes mellitus.  Hence, this study was undertaken to explore the utility of salivary glucose estimation during the treatment and monitoring of diabetes mellitus as it is a non-invasive method of monitoring when compared to serum glucose estimation.
| Materials and Methods|| |
This study was conducted in the Department of Oral Medicine and Radiology and Oral Pathology, College of Dental Sciences, Bapuji Hospital and a Local Diabetic Care and Research Centre, Davangere.
Experimental group and controlled group comprised of 60 patients (37 males and 23 females in age group of 29-73) who were freshly diagnosed for diabetes mellitus. The subjects in the control group were matched for age and sex with those of experimental group [Table 1]. Newly diagnosed diabetic patients whose fasting glucose is more than 126 mg/dl or random blood glucose is more than 200 mg/dl were included in the study. Patients who are already taking treatment for diabetes and with other systemic diseases other than hypertension were excluded. Blood and saliva samples from both experimental and control groups were collected at least 2 h after the breakfast. 0.5 ml of blood was drawn from anticubital vein. 0.5 ml of whole saliva was collected by draining method. Salivary and serum glucose was estimated by glucose oxidase peroxidase method using semiautoanalyzer-Biosystems BTS 310.
| Results|| |
In control group the salivary glucose ranged from 0.7 to 1.3 mg% and the mean was 1.0 ± 0.1 mg%.
In study group, before the treatment of diabetes, the salivary glucose ranged from 1.5 to 8.0 mg% and the mean was 3.10 ± 1.04 mg%. After the control of diabetes, the salivary glucose ranged from 0.6 to 1.8 mg% and the mean was 1.1 ± 0.2 mg%.
The comparison of salivary glucose before treatment and after control of diabetes was done by using paired t -test as same samples were examined twice and difference was statistically highly significant ( P <0.001). Unpaired t -test was used to compare the diabetic and control groups and the difference was statistically significant ( P <0.01).
In control group the serum glucose ranged from 61 to 167 mg% and the mean was 105.7 ±22.3 mg%.
In study group, before the treatment of diabetes, the serum glucose ranged from 205 to 490 mg% and the mean was 309.5 ± 68.2 mg%. After the control of diabetes, the serum glucose ranged from 71 to 167 mg% and the mean was 119.7 ± 27.5 mg%.
The comparisons of serum glucose before treatment and after control of diabetes was done by using paired t -test as same samples were examined twice and the difference was statistically highly significant ( P <0.001). Unpaired t -test was used to compare the diabetic and control groups and the difference was statistically significant ( P <0.01) [Table 2].
The comparisons of serum glucose before treatment and after control of diabetes was done by using paired t -test as same samples were examined twice and the difference was statistically highly significant ( P <0.001). Unpaired t -test was used to compare the diabetic and control groups and the difference was statistically significant ( P <0.01).
The correlation coefficient ( r ) value for salivary and serum glucose in controls was +0.74. The value was found to be statistically highly significant ( P <0.001). The correlation coefficient ( r ) value for salivary and serum glucose before the treatment of diabetes was +0.67 and r value for salivary and serum glucose after diabetes is brought under control was +0.66. The values were found to be statistically highly significant before the treatment of diabetes and also after the control of diabetes ( P <0.001) [Table 3].
Salivary and serum glucose was correlated before the treatment of diabetes and after the control of diabetes and also in control group in different age groups. It was observed that there was no significant correlation between different age and sex groups and salivary and serum glucose ( P <0.05).
| Discussion|| |
Epidemiological studies in India have shown high prevalence of type II diabetes. A series of epidemiological studies in urban South Indians conducted by the Diabetes Research Centre, Madras showed increased prevalence of diabetes. It has increased from 5.2% in 1983 to 8.2% in 1989 and 11.6% in 1995. With the rising trend in the prevalence of diabetes, the number of diabetic patients in India in 2000 was 31.7 millions. India had the largest number of diabetic patients in the world. The number of people with diabetes in India is expected to be more than double by the year 2030, by which time almost 80 million people are expected to have diabetes. In India, the mean age of onset of type II diabetes in men is 44.0 ± 8.3 years and in women the mean age is 42.9 ± 10.0 years. Male predominance is seen, with male to female ratio of 2:1. ,
In our study, male predominance was observed. In present study, the salivary glucose values were higher among the diabetics than in controls and the difference was statistically highly significant ( P <0.001).
Mehrotra and Chawla,  Darwazeh et al.  and Anderson et al.  concluded that salivary sugar values were higher among diabetics than non-diabetics. However, Sharon et al.  found that the glucose concentration in whole saliva was similar in diabetics and in the controls whereas it was significantly higher in the parotid saliva of the diabetic patients.
In our study, correlation between salivary glucose and serum glucose in diabetics and controls was carried out based on Pearson's correlation coefficient. There was correlation between salivary and serum glucose in diabetic patients before the treatment of diabetes and also after the control of diabetes. In controls too, correlation between salivary and serum glucose was found like in diabetic patients. The correlation between salivary glucose and serum glucose was strong in both diabetics as well as in controls. Hence, salivary glucose appears to be a reliable indicator of serum glucose concentrations, particularly in diabetes.
Similar to our study, Darwazeh et al. ,  Belazi et al.  and Amer et al .  too found a positive correlation between salivary glucose and serum glucose. However, in contrast to our study, Sharon et al. ,  Forbat et al.  and Ben-Aryeh et al.  could not establish correlation between salivary glucose and serum glucose.
In a study conducted on metabolically well control adolescents with IDDM by Swanljung et al ,  the glucose level in saliva were of the same magnitude as in the controls which reflect the good metabolic control of the IDDM in these patients. Moreover, salivary glucose values for IDDM patients and controls were found to be significantly correlated with each other.
A decrease in mean salivary glucose was observed by Karjalainen et al.  in the newly diagnosed IDDM cases after 2 weeks on insulin treatment, while blood glucose levels decreased significantly. Salivary glucose levels and mean blood glucose levels in the hyperglycemic state were correlated. Magnitudes of the decrease in salivary glucose and blood glucose levels also correlated with each other. These results suggest that blood glucose levels are related, to certain extent, to salivary glucose levels.
Glucose is a small molecule which easily diffuses through semi-permeable membranes. Thus, large amounts of glucose become available to saliva when blood glucose levels are elevated as in diabetes. Factors other than elevated blood glucose may lead to elevated salivary glucose. Alterations in permeability occurring as a result of basement membrane changes in diabetes may be an additional explanation for the increased concentration of glucose in saliva.  Although membrane abnormalities of parotid gland have been reported in diabetes, there might also be other reasons for the increased salivary glucose content other than changes in glandular tissue. It is possible that part of the registered salivary glucose content originates from gingival fluid.
In the present study, no significant correlation was seen between age and salivary and serum glucose both in diabetic as well as control groups. It was observed that correlation values were less than one and as there was no increase in glucose levels with advancing age, no significant correlation was seen between age and salivary and serum glucose both in diabetic as well as control groups. Similar to our study, Darwazeh et al.  also could not find any significant difference in salivary glucose between either sex.
As a highly significant correlation coefficient was obtained in our study, a regression coefficient was calculated (41.5). Regression coefficient gives the amount of increase or decrease in the serum glucose for a unit change in the salivary glucose. Hence, for a given value of salivary glucose, serum glucose can be predicted by using the regression equation. [Serum glucose = 186 + 41.5 (Salivary glucose)] [Graph 1][Additional file 1] .
The diagnostic validity of salivary glucose was predicted so that it can be used as an indicator of serum glucose concentration. The sensitivity was 100% and was found to be significantly high. The specificity was 78%. Positive predictive value was 82% which was found to be significant. Negative predictive value was 100% which was significantly high. Overall accuracy was also significant which was 89%. Salivary glucose concentration of 1 mg% was taken as the cut-off value. A concentration higher than 1 mg% would mean presence of diabetes mellitus, while concentrations less than or equal to this value would rule out diabetes.
| Conclusion|| |
Although statistically salivary glucose is proved to be a good indicator of presence or absence of diabetes, attention must once again be drawn to the fact that glucose in whole saliva may not be entirely derived from salivary glands. Studies in larger samples and in patients undergoing anti-diabetic treatment would perhaps establish more definitively whether salivary glucose estimation would one day replace serum glucose estimation. Such an event would be in the interest of the patient, since collection of salivary samples is an easy, safe and non-invasive procedure. Our study involved a small sample size, therefore similar studies in larger populations would strengthen our results.
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[Table 1], [Table 2], [Table 3]