Decline of the lung function and quality of glycemic control in type 2 diabetes mellitus

•We evaluate the lung function changes over time in type 2 diabetic patients.•Glycemic control has been monitored during the follow-up of about 5 years.•Pulmonary diffusing capacity declines independently from the glycemic control.•A strict glycemic control slows the decline of the respiratory muscle efficiency.

ObjectiveThe aim of this study was to verify to which extent in type 2 diabetes mellitus respiratory function and respiratory muscle efficiency decline over time in relation to the quality of glycemic control (GC).MethodsForty-five non-smoker diabetic patients without pulmonary diseases performed a complete respiratory function assessment at baseline and after a follow-up of 4.9 ± 0.6 years. The respiratory muscle efficiency was assessed by maximal inspiratory pressure (MIP) and maximum voluntary ventilation (MVV). Patients with an average yearly value of glycosylated hemoglobin ≥ 7.5% at least in two years during follow-up were considered to have a poor GC.ResultsResidual volume and pulmonary diffusing capacity significantly declined over time in the whole sample of patients (p = 0.049 and 0.025, respectively), but without difference between patients with poor (n. 12) and good (n. 33) GC. MIP declined in patients with poor GC (from 83.75 ± 32.42 to 71.16 ± 30.43% pred), and increased in those with good GC (from 76.22 ± 26.00 to 82.42 ± 30.34% pred), but the difference between groups was not significant (p = 0.091). Finally, MVV significantly declined in patients with poor GC (from 70.60 ± 25.49 to 68.10 ± 18.82% pred) and increased in those with good GC (from 66.40 ± 20.39 to 84.00 ± 23.09% pred) with a significant difference between the two groups (p = 0.003).ConclusionThese results show that, in type 2 diabetic patients, respiratory muscle efficiency, but not lung volumes and diffusing capacity, might suffer from a poor GC over time.