Evaluation of serum and salivary glucose in insulin-dependent diabetes mellitus patients

INTRODUCTION

Currently it is estimated that nearly 61.3 million people are suffering from diabetes mellitus in India. It is estimated that by the year 2030, around 101.2 million will be affected by this disease. Diabetes mellitus is an endocrine disease characterized by a shortfall in the production of insulin with consequent alteration of the process of assimilation, metabolism and balance of blood glucose concentration. According to etiology, it is classified, as type I and type II. Type I results in the destruction of the beta cells of the pancreas causing absolute deficiency of insulin, while type II results from cellular dysfunction in resistance to insulin by peripheral tissues.¹

Saliva indeed is a mirror of our blood as these bio-fluids and their molecular components share many similarities. Realization of this fact and the possible utility of saliva as a diagnostic bio-fluid using recent technological advances over the past decades enabled many researchers to develop saliva based technology to detect the transition between health and disease. Tests based on saliva have already made substantial inroads into diagnosis^{2, 6}.

Monitoring people with diabetes involve repeated estimations of plasma glucose either by finger pricks or by intravenous blood sampling. In recent times interest has been increasing in non-invasive diagnostic testing. It is becoming more and more apparent to investigators and clinicians in a variety of disciplines that saliva has many diagnostic uses especially in large scale screening and epidemiological studies.²

The purpose of this study was to evaluate the salivary glucose in IDDM and to compare with healthy non-diabetic controls and also to correlate between serum and salivary glucose levels in IDDM.

MATERIALS AND METHODS

The study was conducted on 20 patients with IDDM and 20 age-matched healthy non-diabetic individuals. The patients were collected from District General Hospital, Dr. Rudrawadi Diabetic Care Centre & Our Dental College & Hospital. Patients with IDDM and individuals who volunteered to participate in the study were included and informed consent was obtained from both the groups, and ethical clearance was obtained from institutional ethical committee. Patients having systemic diseases other than diabetes mellitus and patients with type II diabetes mellitus were excluded from the study.

The saliva samples and intravenous blood samples were collected from the patients with IDDM and age matched healthy non-diabetic controls. The saliva samples were collected between 8-10 am. 2 hours before collection of saliva, the patients were restrained from eating or drinking. Unstimulated whole saliva was collected in a sterilized container over a period of 5 min by spitting method.

Estimation of blood and salivary glucose was done by GOD-POD Method, End Point: determination of glucose after enzymatic oxidation by glucose oxidase. The colorimetric indicator is quinoneimine, which is generated from 4- aminoantipyrine and phenol by hydrogen peroxide under the catalytic action of peroxidase.^{3, 4}

All the estimations were done using auto analyzer, ERBA, Mannheim, chem-5, plus V2. 

RESULTS

The results showed mean salivary values for glucose in IDDM & control group were 2.118±0.41 & 0.813±0.077, respectively. Mean serum glucose values for IDDM group was 213.8±39 mg/dl & for control group was 83.5±6.81 mg/dl respectively. (Table 1)

The t-test & significance of salivary glucose in IDDM & control group was t=14.03, p<0.001 VHS. The t-test & significance of serum glucose in IDDM & control group was t=14.72, p<0.001 VHS. The Karl Pierson co-efficient for correlation between serum & salivary glucose in IDDM group was r=0.984, p<0.01. It showed highly significant +ve correlation between serum & salivary glucose (Table 2 & Fig 1). 

DISCUSSION

Saliva is an organic fluid which will indicate local and systemic alterations, such that the components of saliva can be related to the hormonal, immunologic, neurologic, nutritional and metabolic state of the individual.

As a diagnostic fluid, saliva offers distinctive advantages over serum because it can be collected non–invasively by individuals with modest training. Furthermore, saliva may provide a cost–effective approach to screen larger population.⁶

Our study was intended to evaluate salivary glucose in IDDM patients to compare with healthy non-diabetic control group and also to compare and correlate serum and salivary glucose levels in patients with IDDM. We have included 20 IDDM patients and 20 healthy controls, with their consent. The results revealed that the serum glucose level in IDDM group was 213.8±39 mg/dl (mean±S.D) and in control group it was 83.5±6.81 mg/dl. The salivary glucose levels in IDDM group were 2.118±0.41 mg/dl and in control group it was 0.813±0.077 mg/dl.

The Karl Pierson co-efficient for correlation between serum & salivary glucose in IDDM group was r=0.984, p<0.01, it showed highly significant +ve correlation between serum & salivary glucose.

IDDM is a severe disease that raises blood glucose concentration because of hyperglycaemia and insulinopenia. Fluctuations in water and electrolyte levels may result in xerostomia and other changes in salivary composition.⁷ 

In our study, the salivary glucose levels in IDDM group were significantly higher compared to control group. Further the serum and salivary glucose levels in IDDM group were significantly correlated(r=0.984), these two findings are in agreement with the previous studies done by Maria. A. Belazi et al⁷ , Campbell MJA⁹ , Sharon A et al¹⁰, Kaisa M. Karjalainen⁸ and Darwazeh A et al¹¹ . However other authors such as Marder MZ et al¹² and Mandel ID¹³ have concluded that there is no correlation between glucose levels in saliva and serum of IDDM patients. This conflict could be explained by the different method of saliva collection they performed. The increased permeability of basement membrane in IDDM may lead to an enhanced leakage of serum derived components into whole saliva via gingival crevices. The small molecule of glucose can easily diffuse via the semi-permeable basement membrane. Thus a significant rise in glucose levels of saliva in patients with IDDM could be manifested.⁷

It is generally accepted that diabetes influences varied changes in salivary composition, a very few studies have been carried out and done on IDDM, in our study of IDDM patients we observed that there is increased level of salivary glucose as compared to the control group of healthy subjects and further significant correlation was seen between serum and salivary glucose levels in IDDM patients. The observation derived from the study requires more comprehensive evaluation with large sample size, as our study sample was small but the results of our study will definitely add new dimensions and lay foundation for further research.

CONCLUSION

It can be concluded that there are definite changes in salivary composition, with increased levels of salivary glucose in IDDM patients compared to the healthy controls and further significant positive correlation was seen between the serum and salivary glucose levels in the IDDM patients. The levels of glucose in serum of IDDM patients could be reflected in saliva, hence the estimation of glucose and large scale screening for diabetes could be non-invasive.