BMI Modifies the Relationship Between Glycemic Status and Asthma Severity in Children

To better understand the relationship between HbA1c and asthma outcomes in children living in urban areas, researchers assessed asthma control, lung function, and exacerbations. The researchers hypothesized that higher HbA1c levels were associated with higher asthma morbidity.  The results were published in Journal of Asthma and Allergy.

In their analysis, the researchers included children from the AIRWEIGHS study, which is a randomized controlled trial testing the hypothesis that children with overweight or obesity children would experience greater improvement in asthma control compared with children without overweight or obesity. The trial included 164 children aged 8 to 17 years with asthma from the Baltimore, MD, area; for this analysis, they were examined at baseline and at 3 months, during which HbA1c levels, asthma characterization, body anthropometric measurements, and lung function outcomes were assessed. BMI was also evaluated.

Of 164 children, 112 had available HbA1c measurements ranging from 4.2% to 6.1%, with a mean of 5.3%. Twenty participants had an HbA1c level of 5.7% or above, indicating prediabetes. The correlations between HbA1c and BMI percentile (r=0.023; P=0.74), waist-to-hip ratio (r=0.036, P=0.61), and waist circumference (r=0.08, P=0.26) indicate a weak linear association between HbA1c levels and BMI measures.

Higher HbA1c levels were associated with poorer asthma control, as indicated by a significant increase in Asthma Therapy Assessment Questionnaire (ATAQ) scores: a 1% rise in HbA1c corresponded to a 0.74-point increase in ATAQ score (95% CI, 0.07-1.41; P=0.03), reflecting worse asthma management.

No significant associations were found between HbA1c (as a continuous or categorical variable) and other asthma surveys, lung function, or exacerbations. However, BMI appeared to modify the relationship, with the strongest associations between HbA1c and both maximum symptom days and exacerbations observed in children with lower BMI.

The researchers noted that, “However, in the interaction analysis, BMI percentile and HbA1c were shown to have a significant interaction such that HbA1c’s association with maximum symptoms days and exacerbation risk were greater among those with low BMI 5th percentile when compared to the high BMI 95th percentile. This finding suggests that HbA1c could have a stronger influence among non-obese children with poor glycemic control and underlying metabolic dysfunction, highlighting the complexity of the HbA1c and BMI relationship and its effect on asthma morbidity.”

Reference

Pham H, et al. J Asthma Allergy. 2025;18:649-654. doi:10.2147/JAA.S498269