Metabolic status in diabetes mellitus affects markers for glomerular filtration rate

The present study was performed in newly diagnosed diabetic children to evaluate the effect of metabolic derangement on routine tests for glomerular filtration rate (GFR). Children with (n=16) and without (n=10) ketonuria at diagnosis of diabetes followed a routine clinical treatment program. Serum creatinine, creatinine clearance, serum cystatin C, and iohexol clearance were analyzed at diagnosis and after 20 days of treatment. Iohexol clearance was used as the "true GFR". Serum creatinine and iohexol clearances were not affected by the acute metabolic status or ketonuria. In contrast, serum cystatin C was significantly influenced by ketonuria. Creatinine clearance was an unreliable marker for GFR both in the more deranged and in the balanced metabolic situation.