[Concentration of C-peptide in correlation to kidney function (author's transl)]

Recently, the radioimmunological determination of C-peptide came into interest because of the jugdement of the remaining function of the islet apparatus in insulin-dependent diabetics. As the degradation of C-peptide preferably takes place in the kidney we performed an intravenous glucose load in 32 patients with kidney diseases. The following results were obtained: 1. In patients with a healthy carbohydrate metabolism a clear correlation exists between the concentration of creatinine on the one hand, the creatinine-clearance and the fasting C-peptide concentration respectively the measured amount of C-peptide on the other hand. 2. The more advanced the renal insufficiency the better is the correlation between the parameter of the kidney function and the C-peptide concentration. 3. In diabetic patients there shows to be no clear correlation between the C-peptide levels and the kidney function. --In insulin-dependent diabetics the amount of C-peptide is only of diagnostic use if the renal function is well known.