Exploring the impact of chronic obstructive pulmonary disease (COPD) on diabetes control in diabetes patients: a prospective observational study in general practice.

Background: Little is known about the association between COPD and diabetes control parameters. Aims: To explore the association between comorbid COPD and longitudinal glycaemic control (HbA1C) and systolic blood pressure (SBP) in a primary care cohort of diabetes patients. Methods: This is a prospective cohort study of type 2 diabetes patients in the Netherlands. In a mixed model analysis, we tested differences in the 5-year longitudinal development of HbA1C and SBP according to COPD comorbidity (present/absent). We corrected for relevant covariates. In subgroup effect analyses, we tested whether potential differences between diabetes patients with/without COPD were modified by age, sex, socio-economic status (SES) and body mass index (BMI). Results: We analysed 610 diabetes patients. A total of 63 patients (10.3%) had comorbid COPD. The presence of COPD was not significantly associated with the longitudinal development of HbA1C (P=0.54) or SBP (P=0.33), but subgroup effect analyses showed significant effect modification by SES (P