Impact of Islet Transplantation on Type 1 Diabetes-Related Complication: A Systematic Review

Islet transplantation is a valuable therapy for selected type 1 diabetes mellitus (T1DM) patients, especially those with recurrent severe hypoglycemia, glycemic variability, or impaired hypoglycemia awareness. It improves glycemic control and protects against hypoglycemic episodes. Beyond glucose regulation, islet transplantation may mitigate diabetes-related microvascular and macrovascular complications. We conducted a systematic review to assess its impact on vascular outcomes in T1DM, focusing on islet transplantation alone (ITA) and islet-after-kidney transplantation (IAK). We included studies that quantitatively assessed vascular complications after ITA or IAK in adults with T1DM. Eligible studies compared pre-and post-transplant outcomes or posttransplant outcomes with control groups receiving standard treatment. Twenty-five studies (1,373 patients) evaluated microvascular and macrovascular outcomes using eGFR, ophthalmic e xams, and nerve conduction studies. Islet transplantation was associated with stabilization or improvement in most microvascular complications and longterm renal function preservation. While macrovascular data were less frequent, improvements in vascular health markers such as reduced procoagulant states and atherosclerosis progression were reported, suggesting possible reductions in cardiovascular events and mortality, though data remain limited. Islet transplantation shows clear benefits for microvascular complications and potential advantages for macrovascular outcomes, alongside its established role in improving glycemic stability and quality of life. Systematic Review Registration: PROSPERO Identifier CRD420251036400.