Elevated HbA1c may raise risk for asthma-related hospitalization, impaired lung function

Elevated HbA1c level was associated with increased risk for asthma-related hospitalizations and a small decrease in lung function in adults with asthma who did not have diabetes, researchers reported.

“Asthma hospitalizations result from severe or poorly controlled disease and account for a high proportion of asthma-related health care costs,” Juan C. Celedón, MD, DrPH, FAAAI, the Niels K. Jerne Professor of Pediatrics and professor of medicine, epidemiology and human genetics at University of Pittsburgh and division chief of pulmonary medicine at UPMC Children’s Hospital of Pittsburgh, told Healio. Celedón is also president of the American Thoracic Society. “Whereas insulin resistance and glucose dysregulation had been associated with asthma and asthma severity, the role of an elevated glycated HbA1c on asthma control of severity is less clear.”

The researchers conducted a cross-sectional study to examine the relationship between HbA1c level and hospitalizations for asthma and lung function measures. Celedón and colleagues used data from the UK Biobank to identify a cohort of 47,606 adults aged 40 to 69 years with physician-diagnosed asthma but no diagnosis of diabetes. For this study, HbA1c levels were categorized as normal or as consistent with prediabetes or diabetes.

More than 3% of participants had one or more asthma-related hospitalization. In this group, the mean age was 55.6 years and 32.4% were men.

Researchers reported an association between one or more asthma-related hospitalization and both normal HbA1c level (OR = 1.03; 95% CI, 1.01-1.04) and HbA1c level in the prediabetes or diabetes range (OR = 1.68; 95% CI, 1.18-2.41) after adjusting for age, sex, ethnicity, BMI, average annual household income, current smoking status, pack-years of smoking, fasting time and C-reactive protein. Results also showed a significant, but weak, inverse association between FEV₁ and FVC and normal HbA1c and HbA1c in the prediabetes or diabetes range, according to the researchers.

The researchers cited several limitations of this study, including a lack of data on potential confounders or modifiers of the relationship between HbA1c level and asthma hospitalizations or lung function; possible misclassification of COPD as asthma; and findings that are not generalizable to individuals without asthma and younger populations.

“Pending confirmation in longitudinal studies, these findings suggest that physicians caring for adults with poorly controlled asthma should be aware of potentially undiagnosed prediabetes or diabetes, particularly in high-risk individuals such as those who are overweight or obese,” Celedón told Healio.

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Juan C. Celedón, MD, DrPH, FAAAI, can be reached at juan.celedon@chp.edu.