Effect of Glucose Improvement on Spirometric Maneuvers in Patients with Type 2 Diabetes: The Sweet Breath Study

Gutiérrez-Carrasquilla L, Sánchez E, Barbé F, et al. Diabetes Care. 2019 Apr;42(4):617-24. [CrossRef] [PubMed]

 The authors conducted a prospective interventional study to determine if an improvement in glycemic control affects pulmonary function. Sixty patients with type 2 diabetes and forced expiratory volume in 1 s (FEV1) <90% of predicted were studied. Spirometry was performed at baseline and after a 3-month period in which antidiabetic therapy was intensified. Those with an HbA1c reduction of >0.5% were considered to be good responders (n = 35). Good responders exhibited a significant improvement in spirometric values between baseline and the end of the study (forced vital capacity [FVC]: 78.5 + 12.6% vs. 83.3 + 14.7%, P = 0.029]; FEV1: 75.6 + 15.3% vs. 80.9 + 15.4%, P = 0.010; and peak expiratory flow [PEF]: 80.4 6 21.6% vs. 89.2 6 21.0%, P = 0.007). However, no changes were observed in the group of nonresponders when the same parameters were evaluated (P = 0.586, P = 0.987, and P = 0.413, respectively). Stepwise multivariate regression analysis showed that the absolute change in HbA1c independently predicted increased FEV1 (R² = 0.175) and PEF (R² = 0.323). In contrast, the known duration of type 2 diabetes, but not the amelioration of HbA1c, was related to changes in forced expiratory flow between 25% and 75% of the FVC. In type 2 diabetes, spirometric measurements reflecting central airway obstruction and explosive muscle strength exhibit significant amelioration after a short improvement in glycemic control. The reason for the nonsignificant improvement in spirometry with improved type 2 diabetes control was unclear.