Swedish Study Finds Link Between Asthma and Diabetes

TOPLINE: 

A significant association was found between asthma and type 2 diabetes (T2D), even after adjusting for body mass index (BMI). Additionally, individuals with a sibling affected by one condition had an increased likelihood of having the other condition, indicating shared genetic and environmental factors.

METHODOLOGY:

• Researchers conducted a register-based cross-sectional study between 2009 and 2013 to examine the association between T2D and asthma in Swedish adults and the familial co-aggregation of these conditions.
• A total of 5,229,245 participants aged 25-85 years (50.7% women) were included, of whom 334,680 had only asthma, 241,656 had only T2D, and 25,292 had both conditions; data on physician-diagnosed asthma and T2D were extracted from the National Patient Register and the Swedish Prescribed Drug Register.
• The analysis included adjustments for sex, age, education level, income, and country of birth, with additional adjustment for body mass index (BMI) in a subset of participants. BMI data were obtained from the Swedish Conscription Register for men and the Medical Birth Register for women.
• Familial co-aggregation was assessed by analysing sibling pairs, including 750,153 brothers and 822,241 sisters from the same father and mother as affected individuals, to explore shared genetic and environmental factors.

TAKEAWAY:

• In the total population, individuals with T2D had a 47% increased likelihood of having asthma (odds ratio [OR], 1.47; 95% CI, 1.45-1.49).
• The association was slightly more prominent in men (OR, 1.51; 95% CI, 1.45-1.56) and women (OR, 2.04; 95% CI, 1.96-2.11) with available BMI measurements.
• In the BMI-adjusted analysis of a subset of participants, the association remained significant but was attenuated for both men (OR, 1.45; 95% CI, 1.40-1.51) and women (OR, 1.76; 95% CI, 1.68-1.84).
• Siblings of individuals with asthma had higher odds of developing T2D (OR, 1.13; 95% CI, 1.10-1.15) than siblings of individuals without asthma, indicating shared genetic and environmental risk factors.

IN PRACTICE:

“The family history of either disorder should indicate ascertainment of the other, and future studies should further investigate genetic variants underlying the co-occurrence,” the authors wrote.

SOURCE:

The study was led by Mwenya Mubanga, Karolinska Institutet, Stockholm, Sweden, and was published online on March 23, 2025, in Thorax.

LIMITATIONS: 

The study design could not account for childhood asthma as prescription data were available only from 2005. Additionally, the researchers could not identify individuals who had not been prescribed medication or diagnosed during hospitalisation. The study did not account for other potential confounding conditions, including autoimmune diseases, which may co-aggregate with asthma and T2D. Additionally, the possibility of surveillance bias due to more frequent healthcare contacts in patients with chronic illnesses could not be ruled out. 

DISCLOSURES:

The study received financial support from the Swedish Research Council, the Swedish Heart-Lung Foundation, Region Stockholm, and Stiftelsen Frimurare Barnhuset i Stockholm. The authors declared no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.