:: Physiology and Pharmacology ::

Key words : lung volumes, flow rates,diabetes mellitus

INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

INTRODUCTION

Diabetes is the most common metabolic disorder and its prevalence is increasing in several parts of the world, especially in developing countries like India. Recent epidemiological data showed that the prevalence of diabetes in India is 8-10 %. According to WHO survey, India will be the world's diabetes capital. It has been estimated that 2.4% of rural population and 8.4% of urban population is affected by diabetes (1). Western interference has lead to loss in physical activity and changes in food pattern from traditional unprocessed natural ingredients to highly refined energy dense fatty and sugary fast foods. These two core factors are responsible for the high incidence of diabetes in the years to come (2).

Diabetes mellitus precipitate certain systemic diseases that affects the eye, kidney, nervous system and heart. There is a higher incidence of systemic complications including nephropathy, retinopathy, neuropathy etc. (3). The respiratory diseases associated with diabetes may results in changes in pulmonary volumes, diffusion and elastic properties of the lung as well as the performance of respiratory muscle. In addition to lung disease, chest wall disorder, obesity, neuromuscular diseases, pleural diseases can also cause a similar restrictive pattern of pulmonary function (3). The prevalence of disease is increasing rapidly due to rapid change in life style. Life style factors such as diet, physical activity and mental stress have direct as well as confounding impact on glucose metabolism and insulin sensitivity and therefore could influence the development of diabetes (4).

Although a lot of research work is being carried out on diabetes mellitus (DM) its relation with respiratory function is to be traced out and hence the present study was undertaken to assess the lung functions in diabetic patients taking oral medication and insulin administration from this region of Kerala. The oral medication and insulin administered patient were separately categorized to assess the alterations in respiratory functions associated with the treatment. The study also expected to throws some light into the aspects of body mass index (BMI), Body surface area (BSA), Waist-Hip Ratio (WHR) and anthropometric measurements of DM patients. A survey on disease related with eye, foot, mouth ulcer, kidney problems in DM patients were also carried out along with the study based on the questionnaire.
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METHODS

Screening was done for diabetes and only subjects with proven diabetes mellitus were considered for the present study. The patients were undergoing treatment under medical practitioner in OPD/Ward with oral medication and insulin therapy. Random selection of patients were carried out for the sole purpose of studying lung function using Pulmonary function test (PFT) and categorized on the basis of severity of disease (oral medication and insulin treatment). Twenty subjects who administered oral hypoglycemic drug (Group I) and 20 subjects taking insulin (Group II) were selected from Medical Centre, Kottayam. Age, height, weight, body surface area (BSA), body mass index (BMI) and waist-hip ratio were measured. Only male subjects were selected for the study. Statistical package employed was Students t-test. Age and height matched forty subjects without any health ailment were selected as normal controls for the present study. Lung function tests were, carried out with Vitallograph Compact II Spirometer.
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RESULTS

Mean physical characteristics of oral pills used subjects were age 51.25 years, height - 1.64 m, weight 66.5 kg, BMI - 24.7, waist - 90.25 cm, hip 91.85 cm, chest 91.13 cm, waist -hip ratio 0.98, BSA - 1.72. Mean physical characteristics of insulin administered patients were age 50.8 years, height-1.64 m, weight-65.9 kg, BMI - 24.9, waist - 90.75 cm, Hip - 91.75 cm, chest - 91.5 cm, waist-hip ratio - 0.99, BSA - 1.71 (Table I).

Table I

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Table I: The anthropometric measurements of diabetic patients.

A significant reduction in FEV₁/FVC% (P<0.01) was observed in oral pills used subjects and insulin administered subjects compared to control (Table II). Significant decrease (P<0.05) in FEF_25-75% in Group I subjects was observed as compared to normal control. FMFT showed a significant increase (P<0.005) in Group 11 subjects in comparison to normal controls (Table III).

Table II

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Table II: Comparison of lung volumes between Group I and Group II with controls.

Table III

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Table III: Comparison of flow rates between Group I and Group II with controls.

In present study, the ancillary observation of parameters related to oral pills used patients and insulin-administered patients were collected on the basis of questionnaire (Table IV). From the questionnaire, Group I patients used diabetic pills. Among Group I subjects, 1-2 pills were taken by 7 patients, 3-4 pills were taken by 9 patients per day and 4-5 pills were taken by 2 patients per day.

Table IV

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Table IV: Ancillary observations of parameters related with diabetic patients based on questionnaire.

Among group I patients, sugar level of 5 patients were under the range of 80-120 mg, 6 patients were belong to a range of 121-220 mg and 7 were belong to a range of' 221-320. But in insulin administered group, 2 patients were belong to the range of 80-120 mg, 11 patients were belong to the range of 121-220 mg and only one patient shows the range of 221-320 mg.

Duration of diabetes mellitus in Group I patients, 16 were exposed to diabetes for period of 1-10 years and only one patient belong to the period of 11-20 years. Duration of diabetes in Group II patients, 13 subjects were exposed to diabetes for a period of 1-10 years and 6 patients were placed in the period of 11-20 years and only one subject were between 21-30 years of age group.

Among the patients in Group I the diet control were strictly followed by 10 patients and in Group II patients about 17 patients showed diet control. Among group I patients, 12 subjects show family history of diabetes. In Group II, 13 patients show family history of diabetes. 2 patients in Group I and 3 patients in Group II shows eye defects. Among Group I patients, 6 patients exhibit hypertension and in Group II, 5 patients exhibit high blood pressure. Only one patient shows allergy in both Group I and Group II patients. About 4 of Group I patients and 3 of insulin administering patients exhibit cardiopulmonary disease. The prediction quadrant based on lung function test, 2 oral pills used patients and 2 insulin administered patients shows restrictive diseases. 2 patients among Group I had restrictive and obstructive disease (combined). 4 patients in Group II have obstructive disease, 16 patients of Group I and 14 patients in Group II were normal.
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DISCUSSION

Diabetes mellitus is an important non-communicable chronic disease of global importance. This is characterised by increased sugar levels in the blood due to absolute or relative deficiency of insulin hormone. Nutrition plays an important role in the maintenance of good health. The diet of an Indian is rich in carbohydrates with almost an equal distribution of protein and fats (5). Due to the defect in the insulin secreted P-cell, hormonal level changes which adversely affects the glucose metabolism that lead to permanent diabetes mellitus with characteristic symptoms (4). Niranjan et al. (6) reported that there is a higher incidence of retinopathy, neuropathy, nephropathy etc. together with diabetes. They further shows that lung volumes, septal tissue volume, diffusing capacity were significantly reduced in both NIDDM and LDDM patients as compared to normals.

It is clear from the present study that body mass index (BMI) of Group I and Group II patients were 24.7 and 24.9 (Table I). The over weight range for BMI starts from 25 onwards. So, the patients can be considered to be over weight. Waist-Hip ratio of both Group I and Group II diabetic patients were overweight. Obesity is a well recognised risk factor for diabetes. Increase in BMI to 25 and above increase the risk of diabetes significantly (7). Waist-Hip ratio, a measure of upper body adiposity was also observed above the permissible limit in the present study. Body mass index (BMI) is used as an index of obesity even minimal excess of BMI has been seen to be risk factor for the development of NLDDM used subjects (8). Similar observations were also reported from West that upper body adiposity, measured as the waist to hip ratio (WHR) was associated with greater risk of NIDDM. Diabetic subjects had higher Waist-Hip ratio (WHR) as compared to the non diabetic subjects. There are strong association of oral pills used subjects with BMI and central adiposity, as found in men and women. The studies of Ramachandran et al. (9) showed that BMI increase in men and women may contribute towards the increased prevalence of diabetes. Besides, impaired glucose tolerance (IGT) is another factor for the diabetes. This condition of IGT can be related to BMI, WHR, age etc. The present study also showed that BMI, WHR were higher in diabetic patients.

The present study shows a reduction in FEV₁/FVC% among Group I patients and Group II compared to normals (Table 2). The decrease in FEV₁/FVC% in Group I and Group II subjects may be related with the poor mechanical properties of the lung viz. lung compliance and elastic recoil of lungs. The elastic behaviour of lung can be considered as a mechanical system with two parallel elements. An elastic component is responsible for pressure generated at a low lung volume, whereas less elastic component with high tensile strength causes large changes in pressure with changes in volumes and prevents over extension of the first element. Elastin and Collagen have been designated as morphologic equivalents of these two elements. Total lung capacity (TLC) was lower in diabetic groups. This implies that alteration in the collagen and elastin is the main factor in the diabetic patients (10). Schuyler et al. (11) reported a decrease in total lung capacity, loss of elastic recoil and low lung volumes and abnormal pressure volume relationship in IDDM patients. This may be due to the respiratory muscle weakness. This finding showed that loss of lung elastic recoil in IDDM patients is due to the alterations of both collagen and elastin. Studies conducted by Asanuma et al. (12) reported that forced vital capacity, vital capacity, diffusing capacity were decreased in diabetic patients. This is due to the abnormal peripheral airways, which increases with age and gas transfer was also affected by microangiopathy. Loss of elastic recoil leads to dynamic collapse of small airways during expiration. In addition, myopathic or neuropathic changes affecting the respiratory muscles further impairs the endurance, efficiency of ventilatory pump (6).

Significant reduction in lung volume ratio among Group I and Group II patients were observed in the patients. This denotes lower mechanical properties of lungs and hence restrictive lung disease cannot be ruled out. The lung volume ratios may be helpful in differentiating obstructive and restrictive diseases. The reduced lung capacity might result from abnormal collagen formation as well as decreased rates of connective tissue break down in diabetes patients which shows resistance to oxygen uptake across the alveolar capillary membrane. Significant reduction in FEV_25-75%, among group I subjects (Table III) were compared to normal controls shows a lower airway calibre and higher airway resistance and hence obstructive disease cannot be ruled out. Ashapherwani et al. (13) showed that the initial part of' expiratory FVC curve FEV_25-75% depends on non-bronchopulmonary factors like neuromuscular factors and mechanical equipment factors of inertial distortion of' lungs. The thickening of alveolar wall due to the increased amounts of collagen, elastin basal lamina results in the microangiopathy (14). The study conducted by Singh et al. (15) showed a restrictive pattern of lung disease in DM patients.

There is a decreased trend in expiratory flow rates among both Group I and Group II patients as compared to control which denotes the reduced force generating capacity of expiratory muscle and higher airway resistance. Obese nature of' insulin administered groups and oral pills used subjects may add more problems in performing forced expiratory manoeuvre. The ventilatory functions depend upon the compliance of the thorax-lung system, airway resistance and muscle strength rather than anatomical lung volume. Deterioration in the lung function with advancing age is mainly caused by the change in these functions.

Increase in FMFT in Group II subjects (Table III) showed the increase in duration to conduct the FVC test. This increased duration may be due to lower efficiency of airways and lesser force generating capacity of respiratory muscles and greater airway resistance. Side effects such as breathing difficulty in DM patients taking oral medication may be a factor for increased duration of FMFT and reduced FEV_25-75%.top

REFERENCES

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9. Ramachandran A, Snehalatha C, Latha E, Vijay V, Viswasanathan M. Rising prevalence of NIDDM in urban population in India. Diabetologia 1997; 40: 232-237.

10. Mark R, Schuyier Dennis E, Niewoehner, Scott R, Inkley, Robert Kohn. Abnormal lung elasticity in Juvenile Diabetes Mellitus. Am Rev Resp Dis 1976; 116:118.

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12. Asanuma Y, Fujiya S, Ide II, Agishi J. Characteristics of pulmonary function in patients with diabetes mellitus. Diab Res Clin Pract 1983; 1(2): 95-101.

13. Ashapherwani, Desai AG, Solepure AB. A study of pulmonary functions of competitive swimmers. Indian J Physiol Pharmacol 1989; 4: 228-232.

14. 'Malcolm Sandier. Is the lung a 'Target Organ' in diabetes mellitus. Arch Intern Med 1990;150: 1385 - 1388.

15. Singh S, Sircar SS, Singh KP. Are ventilatory impairments related to early onset and long history of Diabetes ? J Indian Med Assoc 1995; 93(12): 458-459.

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