Is peak expiratory flow rate a predictor of complications in diabetes? The Wisconsin Epidemiologic Study of Diabetic Retinopathy.

The Objective of this study was to determine whether peak expiratory flow rate is a predictor of complications of diabetes. Peak expiratory flow rate was measured at the 10-year follow-up (third examination) of a cohort of persons with younger-onset diabetes. The relationships of progression of diabetic retinopathy by two steps, progression to proliferative retinopathy and of incidences of macular edema, sore or ulcers on feet or ankles, lower extremity amputation, proteinuria, and cardiovascular disease 4 years after this examination with respect to peak expiratory flow rate were evaluated. Study procedures including measurements of blood pressure, height and weight, grading of fundus photographs, peak expiratory flow rate, urinalysis, and medical history were performed according to standard protocols. Peak expiratory flow rate was not associated in univariate analyses with progression of retinopathy, incidences of proliferative retinopathy, macular edema or lower extremity amputation, sores or ulcers on feet or ankles, gross proteinuria, or self-reported cardiovascular disease. However, when using multivariable models to include the effects of other risk factors, peak expiratory flow rate was significantly associated with the combined incidences of sores or ulcers on feet and ankles, or lower extremity amputations (OR=0.61, 95% CI 0.42-0.88). These data suggest that peak expiratory flow rate is a predictor of subsequent complications in the lower extremities in those with long duration of younger-onset diabetes. Evaluating this association in an incipient cohort would illuminate whether the relationship we found is likely to be causal.