The Relationship of Retinopathy Severity to Renal Morphometry in Pre-Clinical Nephropathy in Type 1 Diabetes (DM)
Abstract Number: 1006-P
Authors: RONALD KLEIN, BERNIE ZINMAN, ROBERT GARDINER, PAUL GOODYER, SAMY SUISSA, SANDRA DONNELLY, ALAN SINAIKO, MICHAEL KRAMER, SCOT MOSS, MICHAEL MAUER
Institutions: Madison, WI; Toronto, ON, Canada; Montreal, QC, Canada; Minneapolis, MN
Results: Few epidemiological data exist regarding the correlation of anatomic measures of diabetic retinopathy (DR) and nephropathy (DN), especially early in these disease processes. The aim was to examine the association of severity of retinopathy with histologic measures of DN in persons with Type 1 DM (n=263 at baseline) who were 16 years of age or older with 2 to 20 years of DM and were participants in the Renin-Angiotensin System Study (RASS), a multicenter DN primary prevention trial. All had normal baseline renal function measures including albumin excretion rate (AER), blood pressure (BP), serum creatinine (SCr) and glomerular filtration rate (GFR). DR was determined by masked grading of 30° color stereoscopic fundus photographs of 7 standard fields using the ETDRS severity scale. Baseline renal structural parameters (e.g., mesangial fractional volume (Vv(Mes/glom) and glomerular basement membrane width (GBM)) were assessed by electron microscopic morphometric analyses of percutaneous renal biopsies. No DR was present in 35%, mild nonproliferative (NPDR) in 54%, moderate to severe NPDR in 9%, and proliferative (PDR) in 2% of the cohort. DR severity was not related to AER, BP, SCr or GFR. A greater Vv(Mes/glom) was associated with longer DM duration, higher white blood cell count, older age, higher glycosylated hemoglobin level, greater body mass index (BMI), and increasing severity of DR (total R² 0.29). A greater GBM was associated with age, greater BMI, male sex, and increasing severity of DR (total R² 0.30). Persons with moderate to severe NPDR had a 10% (95% CI 0,20%) greater Vv(Mes/glom) and a 20% (95% CI 12,29%) greater GBM(µm) compared to persons with no DR. These data demonstrate a significant relation between DR and pre-clinical DN in Type 1 DM.