|Year : 2016 | Volume
| Issue : 1 | Page : 35-39
Pulmonary function tests in type 2 diabetes mellitus
Simran Kaur1, Nandini Agarwal2
1 Department of Physiology, All Institute of Medical Sciences, New Delhi, India
2 Department of Physiology, Maulana Azad Medical College, New Delhi, India
|Date of Web Publication||2-Jun-2016|
Department of Physiology, Maulana Azad Medical College, New Delhi - 110 002
Source of Support: None, Conflict of Interest: None
Background: Diabetes mellitus is a chronic disease with microvascular and macrovascular complications. Effect of diabetes on lung capacity has been reported previously but with controversial results. This study will help to reassess whether or not Pulmonary Function Tests should be done in diabetics or not. Aim and Objective: Our study aimed to evaluate pulmonary function testing in patients of type 2 diabetes mellitus (T2DM). Study Design: Randomized Case control study. Materials and Methods: 50 diabetics and 50 matched apparently healthy volunteers taken for this study. After taking an informed consent, all underwent screening with detailed history, anthropometry, blood sugar (fasting and post parandial), and pulmonary functions (using medspiror). Statistical Analysis: Student t test was used to compare PFTs of diabetic and control groups. Frequencies were generated for categorical variables and compared with chi square test. Results: There was significant reduction in all the PFT parameters (FVC%, FEV1% and FEV1/FVC) in diabetics as compared to controls. Thus, mixed obstructive-restrictive pattern of pulmonary dysfunction is seen in diabetics. Also strong positive correlation was seen between fasting blood sugar and FEV1/FVC in diabetics. Although body mass index (BMI) was more in study group versus control group, but the difference was not significant. Conclusion: Lungs are indeed effected in patients of diabetes and pulmonary function testing should be mandatory in diabetics in order to prevent complications thereby improving quality of life.
Keywords: Body mass index, diabetes, pulmonary function tests
|How to cite this article:|
Kaur S, Agarwal N. Pulmonary function tests in type 2 diabetes mellitus. Arch Med Health Sci 2016;4:35-9
| Introduction|| |
Diabetes is the most common metabolic disorder which is on increasing trend globally. According to the International Diabetes Federation, diabetes affects at least 285 million people worldwide, and that number is expected to reach 438 million by the year 2030, with two-thirds of all diabetes cases occurring in low- to middle-income countries. The recently published The Indian Council of Medical Research–India Diabetes (ICMR-INDIAB) national study reported that there are 62.4 million people with type 2 diabetes (T2DM) and 77 million people with pre-diabetes in India. In fact, developing countries like India have to bear the brunt of both communicable diseases as well as non-communicable diseases (NCD) as an epidemic [Table 1], [Table 2], [Table 3].
|Table 3: Diagnostic values for post prandial blood glucose for diabetes|
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Diabetes mellitus (DM) is accompanied by wide spread biochemical, morphological, and functional abnormalities which may precipitate certain complications that affect the neural, cardiovascular, renal systems, and also organs and tissues like skin, liver, collagen, and elastic fibers. It is indeed a multi-system disorder that affect many organs of the body.
The complications related to diabetes pose a significant healthcare burden and disrupt the overall quality of life.
The metabolic disorder is a risk factor precipitating microvascular pathologies leading to autonomic neuropathy, nephropathy, retinopathy, and macrovascular pathologies leading to coronary artery diseases, cerebrovascular accidents, and peripheral vascular diseases. The microvascular complications appear early, within 5 to 10 years and macrovascular complications appear within 15 to 20 years from the onset of diabetes. Among all, pulmonary dysfunction has been reported in patients of diabetes but with plausible pathophysiological mechanism. In fact, it is of debate whether or not spirometry is required in patients of diabetes.
The respiratory diseases associated with diabetes may result in changes in pulmonary volumes, diffusion, and elastic properties of lungs as well as the performance of respiratory muscles., Several histopathological changes are also seen in diabetics. Some researchers like Ljubic et al., showed that diabetes could lead to the development of pulmonary complications due to collagen and elastin changes. While others suggest that increased non-enzymatic glycation of proteins and peptides of the extracellular matrix at chronic high circulating glucose levels may also have an important role in the pathological changes of the lungs in DM patients. Autonomic neuropathy involving respiratory muscles may occur in these patients.
Clear relationship was found by Schnack et al ., between spirometric pulmonary function test and metabolic control. However, Ozmen et al ., failed to show significant differences between patients with diabetes and normal control subjects, differences from normal population-predicted values, or a relationship with diabetes control or duration of disease.
According to Sandler, lung should be considered a target organ in diabetes, but noted that the documented physiological abnormalities were modest in degree, and clinical implications of those findings were not clearly defined in terms of respiratory disease at that time.
Although there is discrepancy in school of thoughts of various researchers, it is important to estimate the relationship between diabetes and its implications on pulmonary reserve so that potential damage can be withheld. With this in mind, our study was designed to compare the pulmonary function in diabetics to those without the disease.
| Materials and Methods|| |
Sixty diabetic subjects of either sex attending/admitting to outpatient department (OPD)/ward at Acharya VinobhaBhave Rural Hospital, Sawangi (Meghe), Wardha, were enrolled for the study. Ten of them were unable to co-operate; in total, we had 50 diabetics and 50 matched apparently healthy staff members belonging to either sex were taken as control group.
Previously diagnosed diabetic patients of more than 1-year duration; with or without hypertension, non- smokers, boay mass index (BMI) < 30 kg/m 2 with no previous history of any respiratory diseases and clinically ruled out cardiovascular diseases.
Patients with acute or chronic respiratory disease or cardiorespiratory disease, with history of smoking or tobacco chewing, underwent abdominal or chest surgery. Pulmonary functions were carried out using the instrument medspiror (a computerized spirometer self-calibrating, which fulfill the criteria for standardized lung function tests) available in the Department of Physiology, Jawaharlal Nehru Medical College, Swangi (Meghe), Wardha. All tests were done according to American Thoracic Society/European Respiratory Society (ATS/ERS guidelines) in a quiet room in sitting position by a trained personnel.
After taking detailed history and relevant clinical examination, an informed consent was taken. Then, we recorded the anthropometric parameters like height and weight and BMI was calculated. Each subject was instructed to visit laboratory with 6 hours of fasting on a specific date, the blood samples (3 ml volume) was drawn for estimation Fasting Blood Sugar.
After demonstrating the technique for carrying out pulmonary function tests, subjects were made to undergo pulmonary function tests, using medspiror, for 3 times at every 15 minutes interval and best of 3 was taken into account.
The forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow rate (PEFR), FEV1/FVC, frontal eye fields (FEF) 25-75% were recorded. The subject was instructed to give blood sample for post prandial estimation of blood sugar 2 hours after the breakfast.
This study was approved by Institutional ethical committee.
Statistical analysis was carried out by statistical package of social sciences (SPSS) version 17.0. Mean and standard deviation were computed for all continuous variables and comparison was done using Student's t-test. Frequencies were generated for categorical variables and compared with chi-square test.
| Results|| |
The demographic profile of the study and control groups depicted in [Table 1] and [Figure 1]. There exists a non-significant (P > 0.05) between the anthropometric parameters, thus both the groups were comparable to one another. Although BMI was more in study group versus control group, but the difference was not significant.
As expected, blood sugar levels (fasting and post parandial) were significantly higher in study group versus the control group.
Our study revealed that FVC% was significantly decreased (P < 0.05) in study group (78.6 ± 8.8) with respect to control group (88.24 ± 15.6). Similarly, FEV1% was also significantly lower in study group (85.40 ± 7.30) as compared to controls (95.26 ± 16.14).
FEV1/FVC was 82.6 ± 4.28 in diabetics versus 87.77 ± 3.90 in controls (P< 0.05). When maximal voluntary ventilation (MVV) and PEFR were 69.0 ± 10.4 and 75.33 ± 13.05, respectively in study group vis a vis 72.0 ± 13.0 and 80.46 ± 19.2 in controls.
Since FVC was significantly decreased (78.6 ± 8.8) in the study group versus control group, which is pathognomic of restrictive airway disease. Although FEV1/FVC ratio was 82.6 ± 4.28, which is >70% but it was significantly decreased in diabetics versus control population; which reflects obstructive airway pattern (P< 0.05). Thus, a mixed (obstructive–restrictive) pattern is seen.
When, we calculated the correlation between fasting blood sugar and FEV1/FVC in study group, a strong positive correlation is seen (r = 0.45) as compared to controls, wherein correlation was 0.0067.
| Discussion|| |
Our study revealed that pulmonary function is indeed impaired in patients of DM as compared to controls. This is in accordance with majority of researchers.,,, But, we found mixed obstructive–restrictive pattern of dysfunction, whereas other studies predominantly emphasize restrictive pattern of dysfunction. Few studies have also published that there is no significant difference in pulmonary function test (PFT) parameters in diabetics as compared to controls.,
But, the main pathophysiology behind the involvement of lungs is an area of research to dwell upon. Conceivably, the non-enzymatic glycosylation of proteins in the lungs and chest wall makes the collagen less susceptible to proteolysis and leads to its accumulation in lung connective tissue.
Non-enzymatically glycosylated collagen seen in diabetic is considerably more resistant to digestion by pepsin and collagenase than non-diabetics. This is the likely explanation for chronic hyperglycemia causing glycosylation of lung collagen and hence less compliant lung parenchyma leading to restrictive changes in lungs. The study by David. A Kaminsky in 2004 speculates that abnormal lung function may precede the diagnosis of diabetes, suggesting that lung may contribute to or at least be commonly affected by factors involved in the pathogenesis of diabetes.
Meo SA et al ., conducted the similar study in Asian population in Saudi Arabia and had reported the similar findings when compared with controls. In 2009, Mo et al ., also observed that some spirometric lung function parameters were decreased in type 2 diabetics and the decline was more in patients with longer duration of diabetes. Post-mortem studies of diabetic people showed an increased thickness of the alveolar wall and small vessel. These changes might be responsible for the limitation of lung expansion and reduction in the ventilatory capacity. Whatever the cause, the findings of Davis et al ., suggested that lung function is an important marker of increased risk of death in patients with diabetes. Monitoring periodic lung function (FEV1 and FVC) has been advocated as a general measure of overall health status as well as a prognostic indicator of premature death from all causes, including cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer. Patients with DM admitted with pneumonia have increased risk of complications and mortality. An association has been found between impaired lung function and death. A 10% decrease in FEV1 was associated with a 12% increase in all-cause mortality in type 2 DM.
BMI, which is modifiable parameter, has often been neglected in various studies.
The effect of BMI in reducing lung function has been well documented by Li AM. The effect of BMI in reducing lung function may be due to reduced chest wall compliance and increased airway resistance. Our study revealed increase in BMI in study group versus controls but the difference was not significant.
Limitations: As this is a pilot study, we included those with diabetes of more than 1-year duration, and did not characterize them according to differences in duration. Also, due to small sample size, it cannot be extrapolated in general population. Larger prospective study will be able to confirm these findings.
| Conclusion|| |
The pulmonary parameters are effected in patients of diabetes, and PFT should be essentially done in these patients for better management. PFT if done in patients presenting with diabetes as a routine OPD procedure will not only help to delay the onset of various respiratory ailments but also help the patient to comply with the various diabetic complications in due course of time. Also, BMI is a modifiable factor, thus achieving and maintaining a normal BMI is paramount in diabetes care.
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[Table 1], [Table 2], [Table 3]