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.