Context: The effect of glycemic control on persisting albuminuria remains unclear. Insulin delivery and glucose variability may be important. Objective: This study aimed to investigate the effect of 1-year treatment with sensor-augmented insulin pump (SAP) or multiple daily injections (MDIs) on albuminuria. Design, Patients, and Methods: This was a randomized controlled open-label parallel trial composed of 60 patients with type 1 diabetes with a history of albuminuria and on stable reninangiotensin system inhibition, were randomly assigned to SAP or MDI. Urine albumin creatinine ratio (UACR) was measured in three urine samples at all visits. Glucose variability and glomerular filtration rate (51Cr-EDTA-GFR) were measured at beginning and study end. Using linear mixed model, change in UACR between groups was analyzed as intention to treat. Main Outcome Measure: Change in UACR was measured. Results: Fifty-five patients (SAP, n = 26; MDI, n = 29) completed the study. Diabetes duration (mean ± SD, 33 ± 12 y), UACR (geometric mean, 99 mg/g; interquartile range, 37-233 mg/g), 51Cr-EDTA-GFR (94 ± 22 mL/min/1.73m2), glycosylated hemoglobin (HbA1c) (9.0 ± 1.1%), glucose variability (calculated as SD), 4.0 ± 1.0 mmol/l; no-group differences (P ≥ .06 for all). After 1 year, change inUACRwas mean,-13%;95%confidence interval,-39 to 22 with SAP vs mean,30%;95% CI,-12 to 92% on MDI treatment (unadjusted P = .051; adjusted for HbA1c, P= .04). HbA1c decreased 1.3 ± 1.0 vs 0.6 ± 1.0% (P = .013), glucose variability decreased 0.9± 1.1 vs 0.3± 1.0 mmol/L (P = .04), and 51Cr-EDTA-GFR declined 5.6 ± 9.6 vs 3.4 ± 13 mL/min/1.73m2 (P = .50) with SAP vs MDI treatment. There were no changes in blood pressure (P = .27). Conclusion: SAP treatment reduced UACR in a randomized controlled trial in type 1 diabetes patients with a history of albuminuria on stable renin-angiotensin system inhibition. Significance was reached after adjustment. SAP treatment reduced HbA1c and glucose variability (calculated as SD).