Clinical significance of urinary C-peptide excretion in children with insulin-dependent diabetes mellitus.
In order to evaluate the accuracy of urinary C-peptide determination and the clinical significance of C-peptiduria for the early course of insulin-dependent diabetes (IDDM), the rate of urinary excretion of C-peptide was determined in 32 children and adolescents with IDDM and correlated with serum C-peptide concentration, urinary excretion of albumin and beta 2-microgloublin and with the glomerular filtration rate (GFR) measured in terms of the clearance of 99mTc-DTPA. The age of the subjects ranged from 9.1 to 17.1 years (mean 13.1) and the duration of diabetes from 0.3 to 11.9 years (mean 4.6). There was a good correlation between postprandial serum C-peptide concentration and the 24-hour urinary C-peptide excretion rate (r = 0.81; p less than 0.001). GFR and urinary albumin excretion were slightly elevated in the diabetic patients as compared with non-diabetic subjects (p less than 0.05 and p less than 0.001, respectively), but C-peptide excretion was unrelated to the degree of hyperfiltration or albuminuria, neither was there any correlation between the excretion rate of beta 2-microglobulin and C-peptide. Glycaemic control was poorer in the diabetic children who had only trace amounts of C-peptide in their urine (less than 0.05 nmol/m2/24 h) than in those with minimal (0.05-1.0 nmol/m2) or moderate 24-hour urinary C-peptide excretion (greater than 1.0 nmol/m2). It is concluded that urinary C-peptide excretion serves very well to reflect residual beta-cell function and is unrelated to the slight renal hyperfunction and albuminuria often seen in diabetic subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
Huttunen
N P
NP
Department of Paediatrics, University of Oulu, Finland.
Knip
M
M
Käär
M L
ML
Puukka
R
R
Akerblom
H K
HK
D000293:Adolescent; D000367:Age Factors; D000419:Albuminuria; D002096:C-Peptide / Q000652:urine*; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000652:urine*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D012016:Reference Values; D012737:Sex Factors; D013997:Time Factors; D001613:beta 2-Microglobulin / Q000652:urine
D002096:C-Peptide; D001613:beta 2-Microglobulin