The Effect of an Inhaled Corticosteroid on Glucose Control in Type 2 Diabetes

Objective: To determine the effect of inhaled corticosteroid (ICS) therapy on glucose control in adults with type 2 diabetes mellitus and coexisting asthma or chronic obstructive pulmonary disease (COPD). Design: A prospective randomized, double-blind, double-dummy placebo-controlled, crossover investigation of inhaled steroids and oral leukotriene blockers. Setting: A United States Department of Veterans Affairs Health Care System outpatient setting. Participants: Adults with type 2 diabetes and asthma or COPD. Methods: Subjects (n= 12) were randomized to receive either inhaled fluticasone propionate (440 mu g twice daily) and oral placebo, or inhaled placebo and oral montelukast (10 mg/ day). After 6 weeks, subjects were switched to the opposite therapy for 6 weeks. The primary outcome measure was the change in the percentage of glycosylated hemoglobin (% HbA1c) at 6 weeks relative to the baseline value. Results: Ten patients completed the study. The difference between the mean within-subject changes in % HbA1c associated with 6-week periods of fluticasone and the mean changes associated with montelukast therapy was small but statistically significant (mean difference= 0.25; P< 0.025). Neither fluticasone nor oral montelukast therapy for 6 weeks led to a significantly different mean % HbA1c compared with the relevant baseline (mean differences= 0.11 and -0.14, respectively). Conclusion: The absence of a clinically significant within-subject difference in the changes in % HbA1c associated with fluticasone versus oral montelukast therapy, or between either therapy or baseline does not warrant recommending changes in therapy for asthma or diabetes in patients with these co-morbid conditions. However, we suggest that clinicians carefully monitor blood glucose control when diabetic patients initiate ICS, especially with higher dosages.