Pulmonary Function Trajectories Over Six Years and Their Determinants in Type 2 Diabetes:The Fremantle Diabetes Study Phase II

Objective: To assess whether there are clusters of people with type 2 diabetes with distinct temporal profiles of lung function changes and characteristics.

Research design and methods: Group-based trajectory modelling (GBTM) identified groups of participants with type 2 diabetes from the community-based observational Fremantle Diabetes Study Phase II (FDS2) who had ≥2 biennial measurements of forced expiratory volume in 1 s as a percentage of predicted (FEV1%pred) over six years. Independent associates of group membership were assessed using multinomial regression.

Results: Of 1,482 potential FDS2 participants, 1,074 (72.5%; mean age 65.2 years, 45.5% female, median diabetes duration 8.0 years) were included in the modelling. The best fitting GBTM model identified four groups; high (19.5%; baseline FEV1%pred 106.5±9.5%, slope 0 %/year), medium (47.7%; FEV1%pred 87.3±8.7%, slope -0.32 %/year), low (25.0%; baseline FEV1%pred 68.9±9.8%, slope -0.72 %/year) and very low (7.9%; baseline FEV1%pred 48.8±9.6 %; slope -0.68 %/year). Compared with the high group, the other groups were characterized by non-modifiable and modifiable risk factors associated with lung function decline in the general population (including ethnicity, marital status, smoking, obesity, coronary heart disease and chronic respiratory disease). The main diabetes-specific significant predictor of group membership was a higher HbA1c in the very low group. There was a graded increase in mortality from 6.7% in the high group to 22.4% in the very low group.

Conclusions: Measurement of lung function in type 2 diabetes could help optimize clinical management and improve prognosis, including addressing glycemic control in those with a very low FEV1%pred.