OBJECTIVES: Chronic obstructive pulmonary disease (COPD) is highly prevalent in the elderly population and typically reduces overall quality of life. COPD exacerbations are commonly treated with corticosteroids. Importantly, rodent and tissue culture models have demonstrated that chronic corticosteroid exposure leads to skeletal muscle insulin resistance followed by type 2 diabetes (T2D).  Our objective is to assess the association between COPD exacerbations and the incidence of T2D in a COPD Medicare population. METHODS: We conducted a case control study of COPD patients from the 2011-2012 Medicare 5% sample Limited Data Set (LDS). Beneficiaries with at least 1 year of continuous enrollment and evidence of > 2 COPD-related claims (>1 primary diagnosis) were included in the study. Cases were defined as a beneficiary with a new claim for T2D, whereas controls lacked evidence of T2D (beneficiaries with evidence of non-incident T2D were excluded). Cases and controls were matched on their propensity to have a new claim for T2D using the Greedy matching algorithm. Rate of moderate (emergency department visits) and severe (hospitalizations) exacerbations, a proxy measure for corticosteroid exposure, were assessed from the first T2D claim or matched healthcare event in controls to the first claim for COPD.  RESULTS: Of 27,456 COPD beneficiaries, 1,457 had incident T2D. Differences between the groups included significantly higher congestive heart failure, arrhythmias, renal failure and obesity. After matching, 2,536 beneficiaries were assigned to cases (n=1,268) and controls (n=1,268). Cases had higher rate of any exacerbations in the Emergency Room (1.97 claims per person) (p=<0.01) and Hospitalizations (2.02 claims per person) (p=<0.01).   CONCLUSIONS: Our findings suggest that patients that were hospitalized and visited the Emergency Room for COPD exacerbations may contribute to the development of T2D.  We believe the risk for developing T2D may be associated with corticosteroid exposure during exacerbations.  Future work should investigate the risk for T2D in COPD patients using corticosteroids.