Borderline Increases in Albumin Excretion Rate and the Relation to Glycemic Control in Subjects with Type I Diabetes

Abstract

We evaluated "borderline" increases in overnight albumin excretion rates (AERs)—i.e., those between the upper 95th percentile of normal (7.6 μg/min) and the lowest value currently considered predictive of nephropathy (30 μg/min)—to determine their importance and to see whether glucose control influenced subsequent changes in the "borderline" AER values. Between 1985 and 1990, we studied 190 subjects with insulin-dependent diabetes mellitus (Type I), analyzing a mean of 6.5 timed overnight urine samples collected per subject. Above-normal AERs were associated with a significantly (by ANOVA) higher mean age (P = 0.03), longer duration of diabetes (P = 0.0002), and greater mean glycohemoglobin values (P = 0.002). The transition rate between borderline and abnormal AERs was significantly higher (P<0.0001, chi-square test) than the direct transition rate between normal and abnormal AERs, thus showing the borderline AER to be a definite intermediate stage. Good and poor glucose control were clearly associated with improvement and worsening, respectively, of the borderline AER values (P = 0.032, chi-square test of trend). More attention to borderline AER values is clearly indicated.

Microvascular complications assessment in adolescents with 2- to 5-yr duration of type 1 diabetes from 1990 to 2006

“…The AER for our adolescents with diabetes showed a skewed distribution; the median AER was 4.2 μg/min, while 6.9 μg/min represented the upper quartile and ≥7.7 μg/min represented the upper quintile. This also approximated the 7.5 μg/min threshold we used based on published studies (10,11) and supports the use of this value to examine the prevalence of early elevation of albumin excretion. A limitation in the interpretation of trends in elevated AER is the change in albumin assays over time.…”

Paraoxonase gene cluster is a genetic marker for early microvascular complications in Type 1 diabetes

“…When an earlier cut‐off for abnormality (AER ≥ 7.5 µg/min) was used, the genotype also increased the risk four‐fold. A continuous elevation of albumin excretion below traditional cut‐offs for microalbuminuria has been shown by others to predict microalbuminuria [11,12] and confirmed in adolescents [13].…”

More on effects of storage time and temperature on measurement of small concentrations of albumin in urine

“…urine pools with two different RIA kits (3,5). A significant, but very slight, decrease of albumin concentration (about 0.6 mg/L after six months) was found only in a low-concentration pool; the values of two intermediate-concentration pools did not decrease.…”