5-year Change in Urinary Albumin Excretion Rate (AER) in the Insulin Resistance and Atherosclerosis Study (IRAS)
Year: 2004
Abstract Number: 1003-P
Authors: ANDREW J. KARTER, DANIEL J. ZACCARO, LYNNE E. WAGENKNECHT, ASSIAMIRA FERRARA, STEVE M. HAFFNER
Institutions: Oakland, CA; Winston-Salem, NC; San Antonio, TX
Results: Elevated AER is a potent cardiovascular risk factor and marker of diabetic nephropathy. AER screening is routinely conducted in diabetes care, although not in non-diabetic subjects. The natural history of AER, particularly in normoglycemic (NGT) and impaired glucose tolerance (IGT) subjects, is poorly understood. We studied 5-year changes in AER status in African American, Hispanic and non-Hispanic white subjects classified at baseline with NGT (n=591), IGT (n=292), newly diagnosed (DM-new; n=142) and prevalent (DM-prev; n=247) type 2 diabetes, from the Insulin Resistance Atherosclerosis Study. AER status was categorized as normoalbuminuric (N) if urine albumin:creatinine ratio<30 mg/g, microalbuminuria (MA) if 30-299 mg/g and proteinuria (P) if >300 mg/g. AER status was assessed at baseline (1992-94) and follow-up (1998-99) exams. Baseline prevalence of elevated AER (MA or P) was 6% in NGT, 6% in IGT, 16% in DM-new, and 23% in DM-prev. Five-year cumulative incidence of elevated AER (among those N at baseline) was 6% in NGT, 7% in IGT, % in DM-new, and 23% in DM-prev. Forty-nine percent of subjects with elevated AER at baseline reverted to N at follow-up. In conclusion, a) nephropathy risk is not elevated in pre-diabetes, but increases steeply after the onset of diabetes; b) normalization of elevated AER is common; and c) AER has low predictive value and should be considered potentially transient and modifiable.Five-year transition of AER status| BASELINE | 5-YEAR FOLLOW-UP AER STATUS |
| Glucose tolerance status (n) | Urinary albumin status (%) | Normoalbuminuria (%) | Microalbuminuria (%) | Proteinuria (%) |
| Normoglycemic (591) | N (94) | 89 | 5 | 0 |
| MA (6) | 4 | 2 | 0 |
| P (0) | 0 | 0 | 0 |
| IGT (292) | N (94) | 88 | 6 | 0 |
| MA (5) | 2 | 2 | 1 |
| P (1) | 0 | 0.3 | 0.3 |
| Diabetes-new (142) | N (84) | 71 | 12 | 1 |
| MA (14) | 6 | 8 | 0 |
| P (2) | 0 | 0 | 2 |
| Diabetes-prevalent (247) | N (77) | 59 | 15 | 3 |
| MA (19) | 11 | 6 | 3 |
| P (4) | 0 | 2 | 2 |
*Percentages add to 100% within each glycemic strata; IGT=Impaired Glucose Tolerance; N = Normoalbuminuria; MA = Microalbuminuria; P = Proteinuria