The temporal relationship between poor lung function and the risk of diabetes

Background: The association between impaired lung function and diabetes risk has been established in the past, however the temporal and causal relationships between the two remain unclear. We assessed the relationship between baseline FEV₁ and FVC and risk of incident diabetes at different time intervals for participants in the Malmö Preventive Project cohort. Methods: Baseline lung function was assessed in 20,295 men and 7416 women during 1974-1992; mean age 43.4 ± 6.6 and 47.6 ± 7.8, respectively. Sex-specific quartiles of FEV₁%predicted and FVC%predicted were created (Q4 = highest; reference). Follow-up time was divided into 10-year time intervals from baseline examination. Cox proportional hazards regression was used to assess the incidence of diabetes according to quartiles of FEV₁ and FVC%predicted, after adjustments for baseline glucose and potential confounding factors. Results: Over 37-years' follow-up there were 3753 and 993 incident diabetes events in men and women, respectively. When comparing FEV₁%predicted in men (Q1 vs. Q4), the HR for diabetes was 1.64 (1.21-2.22) for events 30 years after baseline. A broadly similar pattern was seen for FVC%predicted and for women. Conclusions: Low FEV₁ precedes and significantly predicts future diabetes. This risk is still significant many years after the baseline FEV₁ measurement in middle-aged men. These results suggest that there is a relationship between impaired lung function and diabetes risk beyond the effects of hyperglycemia on lung function.