Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality and is associated with several systemic diseases, such as type 2 diabetes. It has been suggested that comorbidity between COPD and type 2 diabetes is due to shared genetic factors.
To examine the relationship between type 2 diabetes and chronic bronchitis and COPD in adult twins, and to examine to what extent comorbidity between these diseases is explained by shared genetic or environmental factors.
Questionnaire data on chronic bronchitis and hospital discharge data on diagnosed COPD in 13,649 twins, aged 50-71 years, from the Danish Twin Registry were cross-linked with hospital discharge diagnosis data on type 2 diabetes from the Danish National Patient Registry.
The risk of type 2 diabetes was higher in persons with symptoms of chronic bronchitis than in those without symptoms (3.5 vs. 2.3%), OR = 1.57 (1.10-2.26), p = 0.014, and in individuals with diagnosed COPD than in those without the diagnosis (6.6 vs. 2.3%), OR = 2.62 (1.63-4.2), p