Previous research has shown a correlation between new and/or poorly controlled type 2 diabetes mellitus (T2DM) and inhaled corticosteroid (ICS) therapy for the treatment of chronic obstructive pulmonary disease (COPD), as well as a link between increased fracture risk and ICS therapy. Current data are conflicting and inconclusive, and the relationship remains unclear. This matched cohort study involving two UK databases spanning 1983 through 2016. Patients aged 40 years and older who initiated ICS or long-acting bronchodilator (LABP) for the treatment of COPD between 1990 and 2015 were included in the study and stratified into three study cohorts to evaluate the correlation between ICS treatment and diabetes onset (n = 17,970), diabetes progression (n = 804), and osteoporosis onset (n = 19,898). Patients had at least one year of baseline data and at least two years of outcome data and were matched using combined direct matching and propensity scores. Median follow-up for the treatment groups ranged from 3.7 to 5.6 years. ICS patients, compared to LABD patients, had a significantly greater risk for diabetes onset (adjusted hazard ratio [aHR]=1.27; 95% CI, 1.07 to 1.50), but diabetes progression risk was not greater (aHR=1.04; 95% CI, 0.87 to 1.25), nor was osteoporosis risk (aHR=1.13; 95% CI, 0.93 to 1.39). At mean ICS exposures of 500 µg/day or greater, however, compared to less than 250 µg/day, fluticasone propionate–equivalent, the risk of diabetes onset and progression and osteoporosis onset significantly increased.