ObjectivesTo determine the association between type 2 diabetes (T2D) and pulmonary function tests.MethodsAfter conducting an exhaustive literature search, we performed a meta-analysis. We employed the inverse variance method with a random effects model to calculate the effect estimate as the mean difference (MD) and 95% confidence interval (CI). We calculated the heterogeneity with the I2 statistic and performed a meta-regression analysis by sex, body mass index (BMI), smoking and geographical region. We also conducted a sensitivity analysis according to the studies’ publication date, size of the T2D group and the study quality, excluding the study with the greatest weight in the effect.ResultsThe meta-analysis included 66 studies, one longitudinal, 2 case-control and 63 cross-sectional ones, with 11 134 patients with T2D and 48 377 control participants. The pooled MD (95%CI) for the predicted percentage of FEV1, FVC, FEF25–75%, PEF and DLCO were −7.15 (95%CI −8.27, −6.03; p<0.001), −9.21 (95%CI −11.15, −7.26; p<0.001), −9.89 (95%CI −14.42, −5.36; p<0.001), −9.79 (95%CI −13.42, −6.15; p<0.001) and −7.13 (95%CI −10.62, −3.64; p<0.001), respectively. There was no difference in the ratio of FEV1/FVC (95%CI −0.27; −1.63, 1.08; p=0.69). In all cases, there was considerable heterogeneity. The meta-regression analysis showed that between studies heterogeneity was not explained by patient sex, BMI, smoking or geographical region. The findings were consistent in the sensitivity analysis.ConclusionsT2D is associated with impaired pulmonary function, independently of sex, smoking, BMI, and geographical region. Longitudinal studies are needed to investigate outcomes for patients with T2D and impaired pulmonary function.
