Inhalers and blood sugar: Can asthma or COPD medicines raise glucose levels?

Inhaled medicines for asthma and chronic obstructive pulmonary disease (COPD) can potentially affect blood sugar levels, although the impact is typically minor compared to oral steroids. These inhalers, particularly those containing corticosteroids, work primarily inside the lungs but some of the medication can be absorbed into the bloodstream through lung tissue or, if a spacer is not used, through the digestive system.

Once in the bloodstream, corticosteroids can increase glucose production in the liver and reduce the sensitivity of muscles and fat cells to insulin. The extent of this effect depends on the potency of the steroid, the size of the particles, and how much of the dose actually reaches the bloodstream. Higher doses and larger particles are more likely to cause systemic absorption and potentially influence blood sugar levels.

People using high-dose inhaled corticosteroids long-term, especially those with diabetes, prediabetes, or other metabolic risk factors, are more likely to experience changes in blood sugar levels. Combination inhalers containing both a corticosteroid and a long-acting bronchodilator may also contribute to overall exposure. If you notice unexpected changes in your blood glucose readings after starting or changing an inhaler, it's important to monitor your blood sugar closely for one to two weeks and discuss these concerns with your healthcare provider.

Self-discontinuing the inhaler due to blood sugar concerns can be harmful, as uncontrolled asthma or COPD poses its own serious risks. Your doctor may consider adjusting your diabetes medication, changing the inhaler formulation, or adjusting the dose rather than stopping the inhaler independently.