Renal function in relation to metabolic control in children with diabetes of different duration

To evaluate the interpretation of different kidney function tests in diabetic children and teenagers we have studied 47 children with a duration of diabetes up to 5 years, 61 children with a duration of 5.1-10 years and 49 children with a duration of greater than 10 years. Glomerular filtration rate (GFR) measured as inulin clearance or creatinine clearance, clearance PAH (CPAH), filtration fraction (FF), 24-hour urinary excretion of beta 2-microglobulin and albumin were examined and correlated with short- and longterm indices of metabolic control. In all groups of duration GFR as measured by inulin clearance was increased compared with reference values from age matched controls. In patients who had had diabetes for 0-5 years a significant positive correlation was found between inulin clearance and blood glucose during the examination. Inulin clearance was also correlated to HBA1c as well as to 24-hour urinary glucose (mean of 4-6 samples during two years). No such correlation was found in the group who had had diabetes for 5-10 years but in patients with a duration of diabetes greater than 10 years a significant inverse relation was found between GFR and HbA1c. The 24-hour urinary excretion of albumin was significantly higher in all groups of diabetics compared with controls. The urinary excretion of beta 2-microglobulin was similar in diabetics and controls. In the total material no significant correlation could be found between inulin clearance and creatinine clearance.(ABSTRACT TRUNCATED AT 250 WORDS)