Pulmonary Function Tests and Their Associated Factors Among Type 2 Diabetic Patients at Jimma Medical Center, in 2019; Comparative Cross-Sectional Study

BACKGROUND: The presence of widespread lung microvascular circulation and abundant connective tissue with a large reserve raises the possibility that the lung may be a target organ of the pathologic processes induced by type 2 diabetes. Pulmonary function tests (PFTs) are noninvasive medical tests that show how well the lungs are working. OBJECTIVE: The aim was to compare pulmonary function tests (PFTs) and their associated factors among type 2 diabetic patients and non-diabetics at Jimma Medical Center (JMC). METHODS: A comparative cross-sectional study was conducted at JMC, Jimma, Southwest Ethiopia among 298 study participants from April 1 to May 30, 2019. A face-to-face interview with semi-structured questionnaire was conducted. Forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), ratio of FEV(1)/FVC, peak expiratory flow (PEF), and forced expiratory flow (FEF(25−75)) were recorded by using a digital Spirometer. Independent samples t-test, simple and multiple linear regression analysis were used. RESULTS: The present study indicated that means of the PFTs among type 2 diabetics were significantly reduced when compared to their matched non-diabetics (FVC (%) (m=73.7±13.8 vs m=93.8±12.3), FEV(1) (%) (m=76.4±13.4 vs m=93.3±12.4), FEV(1)/FVC (%) (m=78.99±11.4 vs m=96.6±9.33), PEF (L/s) (m=3.91±0.28 vs m=5.03±0.35), and FEF(25–75) (L/s) (m=2.89±0.75 vs m=3.39±0.82)). This study also indicated that body mass index (BMI) (β=−1.93, P<0.001) and fasting blood sugar (FBS) (β=−0.22, P<0.001) were negative predictors of FVC%. BMI (β=−1.93, P<0.001) and FBS (β=−0.29, P<0.001) were negative predictors of FEV1%. BMI (β=−1.403, P<0.001) was a negative predictor of mean FEV(1)/FVC. BMI (β=−1.39 P<0.001) and FBS (β=−0.15, P<0.001) were negative predictors of mean PEF (L/s). BMI (β=−0.075, P<0.001) and FBS (β=−0.075, P<0.001) were negative predictors of FEF(25–75) (L/s). CONCLUSION: The present study showed that there were significantly reduced mean scores of FVC, FEV(1), FEV(1)/FVC, PEF, and FEF(25–75) among type 2 diabetic patients as compared to non-diabetic participants. The FBS and BMI were independent risk factors of the PFTs among the diabetics, unlike among non-diabetic participants.