in English. Outcomes evaluated were overall complications, surgical complications, and longer hospital stay. Subgroup analysis investigated outcomes, such as implant/flap failure, infection, and necrosis. Results: Sixty-five studies met our inclusion criteria and 38 provided data to be included in the meta-analysis. A total of 151,585 patients were included, of which 9299 had diabetes. Women with diabetes were more likely to experience overall complications (11.6% vs 5.6%; p symbolscript 0.0001) and surgical complications (7.7% vs 3.3%; p symbolscript 0.0001), and were more likely to have a prolonged hospital stay ( p symbolscript 0.04) than women without diabetes. Subgroup analysis showed that implant loss (2.5% vs 1.6%; p symbolscript 0.0003), infection (6.8% vs 2.5%; p symbolscript 0.0001) and necrosis (23.8% vs 6.5; p symbolscript 0.001) were significantly higher in women with diabetes. Conclusions: This study provides evidence that diabetes mellitus increases the risk of compli-cations in patients with breast cancer undergoing BR after mastectomy. Prospective studies are required to establish whether diabetes that is well-controlled prior to reconstruction, including diabetes that is paired with adjuvant radiation therapy, reduces the perioperative risks. (c) 2022 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by El-sevier Ltd. All rights reserved.