OBJECTIVE - This population study examines the relationship between LDL density and persistent albuminuria in subjects with type 1 diabetes at the end of the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS - Subjects were classified as persistently normoalbuminuric (albumin excretion rate [AER] <30 mg/d, n = 1,056), microalbuminuric (AER ≥30-299 mg/day, n = 80), and macroalbuminuric (AER = 300 mg/day, n = 24) based on the last two AER measures. RESULTS - Triglyceride (P <0.01) and LDL cholesterol (P <0.01) levels were higher in macroalbuminuric subjects compared with normoalbuminuric subjects. Cholesterol distribution by density- gradient ultracentrifugation showed an increase in intermediate-density lipoprotein (IDL) and a shift in peak LDL from buoyant toward more dense particles with progressive albuminuria. In the entire group, there was a significant negative correlation between the peak buoyancy o f LDL particles and albuminuria (r = -0.238, P <0.001, n = 1,160). This correlation persisted in the normoalbuminuric DCCT group (r = -0.138, P <0.001, n = 1,056). CONCLUSIONS - As albuminuria increases in subjects with type 1 diabetes, dyslipidemia occurs with an increase in IDL and dense LDL that may lead to increased cardiovascular disease.