Effect of metabolic control and duration on exercise-induced albuminuria in diabetic teen-agers.

Nineteen type I diabetic teen-agers without clinical signs of nephropathy with a duration of diabetes varying from 3 to 16.8 years were examined by a standardized exercise test for analysis of urinary excretion of albumin and beta 2-microglobulin. The patients were studied both in poor and improved (but not perfect), metabolic control as defined by HbA1c and blood glucose profiles, and the values were compared to those of 14 age-matched healthy controls. The controls showed no increase in albumin excretion rate during exercise as was found in diabetic patients. The albumin excretion rate during exercise was significantly correlated (p less than 0.05) to systolic blood pressure in the diabetic patients. Blood pressure in the diabetic patients was, however, similar to that of controls both at rest and during exercise. Urinary beta 2-microglobulin did not change during exercise. The urinary albumin excretion during exercise decreased significantly with improved metabolic control in diabetic patients, but the albumin excretion rate was not correlated with either blood or urinary glucose or diuresis during the exercise test. When metabolic control was improved there was a significant correlation between the increase in albumin excretion rate during exercise and the duration of diabetes, indicating that part of the exercise-induced albumin excretion might reflect irreversible morphological changes in the diabetic kidney. This test might therefore have a predictive value for diabetic nephropathy if performed during strict metabolic control.