Background: The use of renin–angiotensin–aldosterone system inhibitors has increased over the past few years. There are conflicting data as to their relationship with acute kidney injury following surgery. Objectives: The objective of the article was to evaluate the risk of acute kidney injury in diabetic older patients treated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers and their medical outcomes following fragility hip fracture surgery. Methods: Consecutive diabetic patients presenting with fragility hip fractures to our primary trauma center between January 2012 and June 2016 were included. Demographic and clinical data, including co-morbidities, medication use, and laboratory results, were collected from the electronic medical records. The primary outcome was the incidence of acute kidney injury; the secondary outcome was 1-year mortality. Results: Two hundred and seventeen patients were included; 125 were receiving treatment with medications targeting the renin–angiotensin–aldosterone system. Demographic and clinical characteristics were similar between groups. No association was found between the use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and the risk of acute kidney injury, which occurred in 25% of the cohort. Univariate analysis revealed that diuretic use, particularly furosemide, increased the risk of acute kidney injury during hospitalization (p = 0.003). However, in a multivariate analysis, only age and estimated glomerular filtration rates were associated with an increased risk of acute kidney injury. Patients with acute kidney injury were found to have increased mortality during the first post-operative year (p < 0.001). Conclusions: Acute kidney injury is a frequent complication after hip fracture surgery in elderly diabetic patients and is associated with increased 1-year mortality; however, it was not found to be associated with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker pre-fracture treatment.