OBJECTIVES: Our previous studies have shown that hypertensive patients with diabetes are susceptible to severe pulmonary complications. This study aims to determine if RAS-modifying medications (angiotensin converting enzyme [ACE] inhibitors and angiotensin receptor blockers [ARBs]) have a beneficial impact on pulmonary complications in patients with hypertension (HTN) controlling for type 1 diabetes (T1D) and type 2 diabetes (T2D). METHODS: Retrospective analyses were conducted using claims data from a US commercial insurance company. The study groups consisted of HTN patients taking either: ACE inhibitors, ARBs, or control (diuretics or calcium-channel blockers). Cox analyses were performed to determine the impact of ACE inhibitors and ARBs on incidence of respiratory complications controlled for comorbidities, demographics, and diagnosis of T1D or T2D as a risk factor. The events included pneumonia and influenza (ICD-9 480–488 [D48]), chronic obstructive pulmonary disease and allied conditions (ICD-9 490–496 [D49]), and other diseases (ICD-9 510–519 [D51]). RESULTS: Our cohort consisted of 97,182 patients with T1D, 123,045 with T2D and 758,695 non-diabetic patients. T1D analysis showed that patients treated with ACE inhibitors had lower incidence of D48 by 16% (hazard ratio [HR]=0.841, 95% confidence interval 0.823-0.860), D49 by 8% [HR=0.921 (0.912-0.931)], and D51 by 11% [HR=0.892 (0.881-0.903)] compared to patients treated with control drugs. ARBs patients also exhibited a lower risk of D48 by 15% [HR=0.850 (0.824-0.877)], D49 by 8% [HR=0.924 (0.911-0.938)] and D51 by 12% [HR=0.882 (0.867-0.896)]. T2D was associated with increased risk in all categories: D48, HR=1.489 (1.447-1.532); D49, HR=1.405 (1.383-1.427); D51, HR=1.391 (1.367-1.415). T1D analysis showed similar decreasing trends for each drug class while T1D increased the risk to a greater extent compared to T2D: D48, HR=2.320 (2.262-2.379); D49, HR=1.527 (1.506-1.548); D51, HR=1.779 (1.753-1.806). CONCLUSIONS: The use of ACE inhibitors and ARBs significantly reduced the risk of pulmonary complications in HTN patients. Both T1D and T2D were associated with increased risk.