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People with both diabetes and asthma appear to face greater metabolic risks than those with either condition alone, according to new observational data.

In a study of more than 18,000 participants from the National Health and Nutrition Examination Survey during 2001-2020, individuals with both asthma and diabetes (most presumed to have type 2 diabetes) had significantly greater impairments in glucose regulation, insulin sensitivity, and lipid metabolism compared with those who had only one condition alone or neither.

Inflammatory markers C-reactive protein (CRP) and high-sensitivity CRP (hs-CRP) were also elevated in the comorbid group, “supporting a hypothesis of a shared inflammatory mechanism,” Sixtus Aguree, PhD, assistant professor at the Indiana University School of Public Health-Bloomington, and colleagues wrote in a poster presented at NUTRITION 2025, the annual meeting of the American Society for Nutrition.

The findings “emphasize the need for integrated clinical strategies that simultaneously target both inflammation and metabolic dysfunction in patients with asthma-diabetes comorbidity,” the authors wrote. “Routine screening for insulin resistance and inflammatory markers in [these] patients may aid in early intervention and risk reduction.”

This points to the need for integrated clinical care, Aguree told Medscape Medical News. “For managing these comorbid conditions, healthcare professionals need to work together. I think that’s a better way to treat the person than working in silos.”

Bidirectional Relationship

Commenting on the findings, Tianshi David Wu, MD, assistant professor of pulmonary and critical care at Baylor College of Medicine in Houston, told Medscape Medical News that these findings align with current evidence.

“Diabetes and asthma have a bidirectional relationship,” Wu explained. “Population studies have shown that patients with diabetes are at higher risk of developing asthma later on, and vice versa. What’s still unknown are the mechanisms that explain this finding.”

Wu added that the researchers had put forth a reasonable hypothesis — that systemic inflammation may play a key role in this association.

“The best way to prove this would be with a trial that specifically targets the type of inflammation you think is driving both asthma and diabetes to see how it affects these conditions.”

As a possible blueprint, he pointed to cardiology, where patients with heart failure and diabetes are preferentially treated with sodium-glucose cotransporter-2 inhibitors, which are effective at treating both conditions.

“In the asthma world, I don’t think the evidence is there yet to recommend any specific diabetes medication, but there is plenty of real-world data suggesting some benefit, and there are two clinical trials ongoing testing semaglutide and metformin to see if they can improve asthma,” Wu said.

Surprising Impact on Insulin Resistance

The study included 18,370 nationally representative US adults. Among them, 8.2% had diabetes without asthma, 7.4% had asthma without diabetes, 83.3% had neither (controls), and 1.2% had both. BMI was highest in the combined asthma-diabetes group (35.9 kg/m² vs 28.2 kg/m² in controls, P < .001), as was waist circumference (117.6 cm vs 97.3 cm, P < .001).

Insulin resistance, defined as a homeostasis model assessment of insulin resistance (HOMA-IR) > 2.5, was present in 41% of controls, 46.8% with asthma only, 77.3% with diabetes only, and 85.6% with both conditions.

The HOMA-IR score in the asthma-diabetes group was significantly higher than in controls (9.85 vs 2.96, P < .001).

Logistic regression analysis confirmed that the odds of insulin resistance were nearly eight times higher in the asthma-diabetes group than in the control group (odds ratio [OR], 7.89; P < .001), even after adjusting for BMI, sex, and medication use.

“We didn’t expect insulin resistance to be that much higher in the combination of asthma and diabetes. That shocked us,” Aguree said.

Asthma alone was not significantly associated with insulin resistance (OR, 0.76; P = .220), “underscoring the additive impact of coexisting diabetes,” the authors wrote in their poster.

Additional Metabolic Outcomes

Absolute values of low-density lipoprotein cholesterol were 115.9 mg/dL and 114.5 mg/dL, respectively, for controls and asthma only, vs 98.9 mg/dL and 104.8 mg/dL for diabetes only and asthma-diabetes groups, respectively. The lower value in those with diabetes is likely due to greater use of statins, Aguree noted.

In contrast, compared with controls, those in the asthma-diabetes group had significantly lower levels of high-density lipoprotein (HDL) cholesterol, while triglycerides and the triglyceride/HDL ratio were higher (P < .001 for all). Systolic blood pressure was also significantly higher in the comorbid group (P < .001), as was diastolic blood pressure, although to a lesser extent (P = .012).

A1c levels were 5.41% in controls and 5.46% in the asthma-only group, both significantly lower than levels in the diabetes group (7.34%) and the comorbid group (7.11%), Aguree said.

Log-CRP values were 0.530 units higher in the asthma-diabetes group than in controls (P < .001), as were hs-CRP (1.70 mg/L vs 0.60 mg/L, P < .001).

Aguree and colleagues are now expanding their analysis to include longitudinal data and evaluate integrated interventions, such as combined anti-inflammatory and glucose-lowering medications, as a means of reducing the burden of both conditions.

Aguree had no disclosures. Wu declared receiving funding from the National Institutes of Health and the American Lung Association. 

Miriam E. Tucker is a freelance journalist based in the Washington DC area. She is a regular contributor to Medscape Medical News, with other work appearing in the Washington Post, NPR’s Shots blog, and Diatribe. She is on X @MiriamETucker and BlueSky@miriametucker.bsky.social.