Systemic side effects of inhaler corticosteroids (IC) are quite rarely. It is also well known that systemic use of corticosteroids for a long period of time may have diabetogenic effects. In this study, the relationship between use of IC in patients with bronchial asthma and tendency of development of diabetes was investigated via oral glucose tolerance test. Eighty three patients with bronchial asthma and 34 healthy subjects without any known disease as a control group were enrolled the study. Asthma group and control group were similar according to gender, age and BMI. Mean period for the diagnosis of asthma was 8.9±6.4 years, for IC use was 4.2±2.7 years and mean daily dose of IC was 616.66±355.62 µgr. Fasting blood glucose (FBG) for asthma group who were on IC and for control group were 92.96±6.82 mg/dl and 93.05±12.51 mg/dl, respectively. Following 75 gr OGTT, glucose levels for asthma group and control group were 110.21±32.17 mg/dl and 109.08±28.41 mg/dl, respectively. FBG levels and 2-hour glucose levels separately in both groups were not statistically significant (p0.05). In asthma group, correlations between duration of IC use and, FBG and 2-hour glucose levels, and also between dose of IC and FBG and 2-hour glucose levels were evaluated. Statistically significant but mild positive correlation was seen between duration of IC (4.2±2.7 year) use and 2-hour glucose levels (110.21±32.17 mg/dl) (p=0.007, r=0.292). In conclusion, in patients with asthma, mild positive correlation between IC use and 2-hour glucose levels was observed. Our findings may point out that IC use over a long period of time may lead glucose intolerance.