EXERCISE VERSUS OVERNIGHT ALBUMIN EXCRETION RATES IN SUBJECTS WITH TYPE-1 DIABETES

Diabetic nephropathy is the leading cause of new cases of renal failure in the US and Europe. An elevated albumin excretion rate (AER) on an overnight urine sample is considered an early predictor of end-stage renal failure. An elevated AER on a post-exercise urine sample has previously been considered to be an even earlier marker of renal damage, In a longitudinal prospective study, 373 subjects with insulin-dependent (type l)diabetes mellitus had a total of 714 renal evaluations, each of which included one exercise and two overnight urine collections for AER determinations. All subjects were at least 13 years old and had diabetes for at least 4 years. There was a strong correlation between exercise and overnight AERs (r = 0.74, P < 0.001). For the 60 subjects with an initial borderline increase of either overnight or exercise AER, the overnight AER values (7.6-20 mu g/min) progressed first for 52% of subjects whereas the exercise AERs (41-114 mu g/min) progressed first for 43% of subjects (5% had simultaneous elevations of both). For the 22 subjects in which an abnormal overnight (> 20 mu g/min) or exercise (> 114 mu g/min) value was detected first, 17 (77%) had an elevated exercise AER first, whereas only 4 (18%) had an elevated overnight AER first. This study shows that an increase of either the exercise or the overnight AER can occur first, dependent upon the level of abnormality being considered. The two tests correlate closely with one another. The previous misconception that an elevation in exercise AER preceded the elevation in overnight AER occurred because values for normal, borderline and abnormal exercise AERs had not been set to correspond with normal, borderline and abnormal overnight AERs.